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Establishing effective mitigation strategies to reduce the spread of influenza virus requires an improved understanding of the mechanisms of transmission. We evaluated the use of a controlled human infection model using an H3N2 seasonal influenza virus to study critical aspects of transmission, including symptom progression and the dynamics of virus shedding. Eight volunteers were challenged with influenza A/Perth/16/2009 (H3N2) virus between July and September 2022 at Emory University Hospital. Viral shedding in the nasopharynx, saliva, stool, urine, and respiratory aerosols was monitored over the quarantine period, and symptoms were tracked until day 15. In addition, environmental swabs were collected from participant rooms to examine fomite contamination, and participant sera were collected to assess seroconversion by hemagglutination inhibition or microneutralization assays. Among the eight participants, influenza virus infection was confirmed in six (75%). Infectious virus or viral RNA was found in multiple physiological compartments, fecal samples, aerosol particles, and on surfaces in the immediate environment. Illness was moderate, with upper respiratory symptoms dominating. In participants with the highest viral loads, antibody titers rose by day 15 post-inoculation, while in participants with low or undetectable viral loads, there was little or no increase in functional antibody titers. These data demonstrate the safety and utility of the human infection model to study features critical to influenza virus transmission dynamics in a controlled manner and will inform the design of future challenge studies focused on modeling and limiting transmission.CLINICAL TRIALSThis study is registered with ClinicalTrials.gov as NCT05332899., Importance: We use a controlled human infection model to assess respiratory and aerosol shedding kinetics to expand our knowledge of influenza infection dynamics and help inform future studies aimed at understanding human-to-human transmission., Competing Interests: N.G.R. receives consulting fees from Krog and participates on the advisory boards of Moderna, Sanofi, Seqirus, and Pfizer. M.F.E. recieves consulting fees from Medtronic and Boston Scientific. L.C.M. receives consulting fees from MITRE.

Introduction: To evaluate the cost and efficiency of suture-mediated percutaneous closure (SMC) compared to manual compression (MC) after atrial fibrillation (AF) ablation. SMC has been demonstrated to be efficacious in reducing hemostasis and bedrest times after AF ablation. To date, randomized data comparing the direct and indirect cost between the two techniques have not been described., Methods: We conducted a 1:1 randomized trial comparing SMC to MC following AF ablation. The primary endpoints have been previously published. However, secondary endpoints pertinent to indirect cost including complication rates, hospital utilization (i.e., delays in discharge, additional patient encounters, nursing utilization), pain, patient reported outcomes, as well as the direct costs of care associated with AF ablation were collected. We also performed secondary analysis of the primary endpoint to evaluate for a learning curve, and subgroups analysis comparing efficacy across different numbers of access sites and compared to those in the MC group with a figure-of-eight suture (Fo8), that could potentially have impacted the relative efficiency of the procedure., Results: A total of 107 patients were randomized and included: 53 in the SMC group and 54 in MC. A learning curve was observed in the SMC group between the first and second half of the study group (p = 0.037), with no such difference in the MC group. After accounting for the number of access sites, time to hemostasis remained shorter in the SMC Group (p = 0.002). Compared to those in the Fo8 arm (n = 37), the time to hemostasis remained shorter in the SMC group (p = 0.001). Among those planned for same-day discharge, there were more delays in the MC group (31.5% vs. 11.3%, p = 0.0144). Rates of major and minor complications were similar between SMC and MC groups at discharge (p = 0.243) and 30 days (p = 1.00), as were nursing utilization, self-reported pain, and overall patient reported outcomes. The overall cost of care related to the procedure was similar between the MC and SMC groups ($56 533.65 [$45 699.47, $66 987.64] vs. $57 050.44 [$47 251.40, $66 426.34], p = 0.601)., Conclusion: SMC has been shown to decrease time to hemostasis and ambulation and facilitate earlier same-day discharge after AF ablation without an increase in direct or indirect costs., (© 2024 The Author(s). Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Background: Inappropriate therapy (IAT) is an undesirable side effect of implantable cardiac defibrillator (ICD) therapy. Early studies with the subcutaneous ICD (S-ICD) showed relatively high inappropriate shock (IAS) rates. The PRAETORIAN (Prospective Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) trial demonstrated that the S-ICD is noninferior to the transvenous ICD (TV-ICD) with regard to the combined end point of IAS and complications. This secondary analyses evaluates all IAT in the PRAETORIAN trial., Methods: This international, multicenter trial randomized 849 patients with an indication for ICD therapy between S-ICD (n=426) and TV-ICD therapy (n=423). ICD programming was mandated by protocol. All analysis were performed in the modified intention-to-treat population., Results: In both groups 42 patients experienced IAT (48-month Kaplan-Meier estimated cumulative incidence, 9.9% and 10.1%, respectively; hazard ratio (HR), 0.99 [95% CI, 0.65-1.52]; P =0.97). There was no significant difference in patients experiencing IAS between both groups ( P =0.14). In the S-ICD group, 81 IAT episodes with 124 IAS and 1 inappropriate antitachycardia pacing occurred versus 89 IAT episodes with 130 IAS and 124 inappropriate antitachycardia pacing in the TV-ICD group. IAT episodes were most frequently caused by supraventricular tachycardias in the TV-ICD group (n=83/89) versus cardiac oversensing in the S-ICD group (n=40/81). In the TV-ICD group, a baseline heart rate >80 bpm (HR, 1.99 [95% CI, 1.05-3.76]; P =0.03), a history of atrial fibrillation (HR, 2.66 [95% CI, 1.41-5.02]; P =0.003), and smoking (HR, 2.46 [95% CI, 1.31-4.09]; P =0.005) were independent predictors for IAT. A QRS duration >120 ms was an independent predictor for IAT caused by cardiac oversensing in the S-ICD group (HR, 3.13 [95% CI, 1.34-7.31]; P =0.008). Post-IAS interventions significantly reduced IAS recurrence in both groups ( P =0.046)., Conclusions: There was no significant difference in IAT and IAS rates between the S-ICD and TV-ICD in a conventional ICD population, but causes and predictors for IAT differed between the devices. After the first IAS, an intervention significantly reduced the recurrence rate of IAS., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022., Competing Interests: Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cardiac, and has stock options from AtaCor Medical, Inc. Dr El Chami reports consultancy fees from Boston Scientific and Medtronic. Dr Mittal reports consultancy fees from Boston Scientific and Medtronic.Dr Neuzil reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. K.M. Kooiman reports consultancy fees from Boston Scientific. Dr Lambiase reports educational and research grants from and is in the research board of Boston Scientific, and reports research grants from Abbott. Dr Vernooy reports consultancy fees from Medtronic and Abbott. M.C. Burke is a consultant, receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. Dr Wright has consultancy arrangements with Boston Scientific and Medtronic and a research grant from Boston Scientific. Dr Nordbeck reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. Dr Miller reports consultancy fees from Boston Scientific. Dr Whinnett is an advisor for Boston Scientific, on the advisory board for Medtronic and Abbot, and reports speaker fees from Medtronic. The other authors report no conflicts.

Background: Transvenous lead extraction (TLE) success and safety are heavily influenced by lead dwell time., Objective: In this study, we aim to compare the clinical effectiveness and safety of TLE between young and old leads., Methods: We retrospectively identified all TLE procedures at Emory Healthcare from 2007 to 2023. Baseline patients' characteristics and procedural details were collected. The cohort was categorized based on the oldest lead dwell time in each procedure. The very long dwell time (VLDT) group included all procedures with the oldest lead dwell time, ≥15 years, whereas the control group included all procedures with the oldest lead dwell time <15 years. TLE outcomes were compared between the 2 groups., Results: Of the 1717 TLE procedures, 114 procedures (6.6%) included leads with dwell times ≥15 years. Patients in the VLDT group were older and had a higher number of targeted leads; 57% of TLE in the VLDT group were for infectious indications. Lead extraction procedural and clinical success were significantly lower in the VLDT group compared with the control group (75% vs 95%, 83% vs 97%, P < .001, respectively). There was a trend toward a higher major complications rate in the VLDT group compared with the control group (3.5% vs 1.3%, P = .058)., Conclusion: TLE of VLDT leads has a lower procedural and clinical success and a higher complication rate than TLE of leads with a shorter dwell time. These results will allow electrophysiologists to quantify risks and benefits of abandoning leads at the time of lead revisions or upgrades., Competing Interests: Disclosures Dr El-Chami is a consultant for Boston Scientific and Medtronic. The other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: One common mode of lead failure is insulation breach, which may result in myopotential noise and device malfunction. "Pseudo-unipolarization" of bipolar pacing stimuli, as observed from a routine 12-lead electrocardiogram (ECG) due to stimulus current leak, has been observed with insulation breaches., Objective: We sought to characterize this electrocardiographic finding to detect this type of lead malfunction., Methods: A total of 138 transvenous leads were analyzed, including 88 with known malfunction and 50 normal leads. The amplitude of a bipolar pacing stimulus on the ECG was recorded and compared with a control data set of newly implanted leads with bipolar stimuli normalized for output., Results: The malfunction group consisted of 61% right atrium and 39% right ventricle leads with mean pacing output of 2.74 V at 0.5 ms. There was a significant difference in ECG bipolar stimulus amplitudes at time of identification of failure (7.89 ± 7.56 mm/V; P < .001) compared with those of normal leads (0.86 ± 0.41 mm/V). Receiver operating characteristic curve for the prediction of lead malfunction based on absolute ECG amplitude displayed an area under the curve of 0.93 (95% CI, 0.891-0.969). When normalized for programmed stimulus output, a cutoff of 5 mm/V demonstrated a sensitivity of 91% and a specificity of 92% (area under the curve, 0.967; 95% CI, 0.938-0.996)., Conclusion: The maximum amplitude of a bipolar pacing stimulus on the ECG is significantly lower in normal functioning leads compared with those with known malfunction. This simply derived variable demonstrated good accuracy at identifying lead failure due to insulation breach., Competing Interests: Disclosures The authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: Leadless pacing is a safe and effective alternative to transvenous pacing for bradycardia. Micra AV is a leadless, single-device solution that provides atrioventricular synchronous ventricular pacing therapy. Early results from the Micra AV CED study showed reductions in short-term complications associated with the Micra AV leadless pacemaker among US Medicare patients. The objective of this study is to compare chronic complications, re-interventions, and all-cause mortality at 2 years between patients implanted with a Micra AV leadless pacemaker and a traditional dual-chamber transvenous (DC-TV) pacemaker., Methods and Results: Patients implanted with a Micra AV leadless pacemaker (n = 7552) or a DC-TV pacemaker (n = 110 558) in 2020 and 2021 were identified using device registration-linked Medicare administrative claims data. Competing risk models compared the unadjusted and propensity score overlap weight-adjusted complication, re-intervention, and all-cause mortality rates of Micra AV and DC-TV patients at 2 years. Micra AV patients had significantly more comorbidities (end-stage renal disease 14.9 vs. 2.0%, P < 0.0001; renal dysfunction 47.9 vs. 34.2%, P < 0.0001; diabetes 46.2 vs. 38.3%, P < 0.001; congestive heart failure 41.4 vs. 30.6%, P < 0.0001). Two years post-implant, Micra AV patients had lower complication rates [adjusted 5.3 vs. 9.6%, hazard ratio (HR): 0.54, 95% confidence interval (CI) 0.49-0.61, P < 0.0001] and lower re-intervention rates (adjusted 3.5 vs. 5.6%, HR: 0.62, 95% CI 0.54-0.72, P < 0.0001) than DC-TV patients. Upgrades to cardiac resynchronization therapy were low in both groups (adjusted 1.6 vs. 1.7%, P = 0.40), as were Micra AV upgrades to a dual-chamber system (adjusted 1.4%). All-cause mortality rates remained higher in Micra AV than in DC-TV patients (unadjusted HR: 2.48, 95% CI 2.35-2.62, P < 0.0001; adjusted HR: 1.53, 95% CI 1.44-1.62, P < 0.0001)., Conclusion: Patients implanted with Micra AV had lower complications and re-intervention rates at 2 years than patients implanted with a traditional DC-TV pacemaker. All-cause mortality remained higher in Micra AV patients, likely due to their higher comorbidity burden and other differences in baseline characteristics., Clinical Trial Registration: ClinicalTrials.gov ID NCT04235491., Competing Interests: Conflict of interest: M.F.E.-C. consults for Medtronic and Boston Scientific. G.C. is supported by CTSA award no. UL1 TR002243 from the National Center for Advancing Translational Sciences and consults for Medtronic and Boston Scientific and on the Speakers Bureau for Medtronic and Spectranetics. J.P.P. is supported by R01HL128595 from the National Heart, Lung, and Blood Institute, receives research grants from Abbott, American Heart Association, Association for the Advancement of Medical Instrumentation, Bayer, Boston Scientific, and Philips, and consults for Abbott, AbbVie, Ablacon, AltaThera, ARCA Biopharma, Biotronik, Boston Scientific, Bristol Myers Squibb, LivaNova, Medtronic, Milestone, ElectroPhysiology Frontiers, Itamar, Pfizer, Sanofi, Philips, ResMed, and Up-to-Date. L.H., C.L., and K.S. are Medtronic employees and minority stockholders., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Most studies of device-detected atrial fibrillation (AF) have recommended indefinite anticoagulation once a patient crosses a particular threshold for AF duration or burden. However, durations and burdens are known to fluctuate over time, but little is known about the magnitude of spontaneous fluctuations and the potential impact on anticoagulation decisions., Objective: To quantify spontaneous fluctuations in AF duration and burden in patients with implantable loop recorders (ILRs) METHODS: We reviewed all ILR interrogations for patients with non-permanent AF at our institution from 2018 to 2023. We excluded patients treated with rhythm control. The duration of longest AF episode at each interrogation was classified as < 6, 6-24, and > 24 h, and the AF burden reported at each interrogation was classified as < 2%, 2%-11.4%, and > 11.4%., Results: Out of 156 patients, the mean age at ILR implant was 70.9 ± 12.5 years, CHA 2 DS 2 -VASc score was 4.2 ± 1.8, duration of ILR follow-up was 23.4 ± 11.2 months, and number of ILR interrogations per patient was 18.0 ± 8.9. The duration of longest AF episode at any point during follow-up was < 6 , 6-24 , and > 24 h in 110, 30, and 16 patients, respectively. Among the 30 patients with a longest AF episode of 6-24 h at some point during follow-up, out of 594 total ILR interrogations, only 75 (12%) showed a longest episode of 6-24 h. In the remaining 519 interrogations, the longest episode was < 6 h. In patients with a longest episode of > 24 h at any point during follow-up (n = 16), only 47 out of 320 total ILR interrogations (15%) showed an episode of > 24 h. When evaluating AF burden, 96, 38, and 22 patients had maximum reported AF burdens of < 2%, 2%-11.4%, and > 11.4% at any point during ILR follow-up. Among those with a maximum burden of 2%-11.4% at some point during follow-up (n = 38), out of 707 ILR interrogations, only 76 (11%) showed a burden of 2%-11.4%. In the remaining 631 interrogations, the burden was < 2%. In the 22 patients with a burden > 11.4% at some point during follow-up, only 80 out of 480 interrogations (17%) showed a burden of > 11.4%. In 65% of interrogations, the burden was < 2%., Conclusion: Significant, spontaneous fluctuations in AF burden and duration are common in patients with ILRs. Even in patients with AF episodes of 6-24 h or > 24 h at some point during follow-up, the vast majority of interrogations show episodes of < 6 h. Similarly, in patients with burdens of 2%-11.4% or > 11.4% at some point during follow-up, the vast majority of interrogations show burdens of < 2%. More data are needed to determine whether crossing an AF burden or duration threshold once is sufficient to merit lifelong anticoagulation or whether spontaneous fluctuations in AF burden and duration should impact anticoagulation decisions., (© 2024 Wiley Periodicals LLC.)

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to overcome the risk of lead-related complications associated with the transvenous implantable cardioverter-defibrillator (TV-ICD). In contrast to the TV-ICD, the S-ICD is a completely extrathoracic device. Subsequently, complications differ between these 2 implantable cardioverter-defibrillators, which might impact patient perceptions of the therapies. This prespecified secondary analysis of the PRAETORIAN trial evaluates differences in quality of life., Methods: The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) randomized patients with an implantable cardioverter-defibrillator indication, without the need for pacing to S-ICD or TV-ICD therapy. Two questionnaires were collected at baseline, discharge, 12 months, and 30 months. The Duke Activity Status Index measures cardiac-specific physical functioning, and the 36-Item Short Form Health Survey measures physical and mental well-being, with the subscales bodily pain and mental health being of interest in this analysis. Mann-Whitney U tests were used to compare study arms, and a mixed model was used to describe the questionnaire outcomes over time., Results: Patients were randomized to S-ICD (n=426) and TV-ICD (n=423). In the S-ICD group, 20% were women versus 19% in the TV-ICD group. The median age was 63 (interquartile range, 54-69) years in the S-ICD group versus 64 (interquartile range, 56-69) years in the TV-ICD group. There were no significant differences in the Duke Activity Status Index and 36-Item Short Form Health Survey subscales for bodily pain and mental health between the groups at any time point. Patients with a shock in the last 90 days had significantly lower scores for social functioning ( P =0.008) and role limitations due to emotional problems ( P =0.001) than patients without a shock, but this effect did not differ between treatment arms., Conclusions: In a large randomized cohort of patients with an S-ICD or TV-ICD, no difference in overall quality of life was observed. However, implantable cardioverter-defibrillator shocks resulted in a reduction in quality of life, regardless of the device type or appropriateness., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022., Competing Interests: Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac and has stock options from AtaCor Medical, Inc. Dr El Chami reports consultancy fees from Boston Scientific and Medtronic. Dr Mittal reports consultancy fees from Boston Scientific and Medtronic. K.M. Kooiman reports consultancy fees from Boston Scientific. Dr Lambiase reports educational and research grants from and is in the research board of Boston Scientific, and reports research grants from Abbott. Dr Vernooy reports consultancy fees from Medtronic and Abbott. M.C. Burke is a consultant and receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. Dr Wright has consultancy arrangements with Boston Scientific and Medtronic and iRhythm and a research grant from Boston Scientific. Dr Nordbeck reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. Dr Miller reports consultancy fees from Boston Scientific. Dr Whinnett is an advisor for Boston Scientific and is on the advisory board for Medtronic and Abbot and reports speaker fees from Medtronic. The other authors report no conflicts.

Background: Because of differences in chest wall anatomy, female patients may have higher rates of subcutaneous implantable cardioverter-defibrillator (S-ICD) pocket-related complications., Objective: We sought to evaluate sex-based outcomes after S-ICD implantation., Methods: Patients implanted with an S-ICD at Emory Healthcare between 2010 and 2023 were included in the analysis. Patients' clinical characteristics and post-S-ICD implantation complications were collected., Results: There were 429 male patients (68%) and 199 female patients (32%) observed for a median duration of 2.3 years (0.6-4.4 years). Male and female patients had comparable rates of diabetes (28%), end-stage renal disease (29.5%), ejection fraction (30.2% ± 13.4%), and body mass index (29.1 ± 6.6 kg/m 2 ). There was no statistical difference in the incidence of shocks between men and women (26.3% vs 20.1%; P = .09), including appropriate shocks (14.7% vs 12%; P = .98) and inappropriate shocks (11.7% vs 9.5%; P = .98). Pocket-related complications occurred in 21 patients; these included pocket infection (n = 12), wound dehiscence (n = 7), and hematoma requiring drainage (n = 2). Female patients had a significantly higher pocket-related complication rate compared with male patients (7.2% vs 2.5%; P = .016). In controlling for age, body mass index, diabetes, and end-stage renal disease, female patients had higher odds of pocket-related complications compared with male patients (odds ratio, 3.15; 95% confidence interval, 1.27-7.75). Pocket-related complications decreased after 2018 compared with before 2018 (6% vs 2.6%, P = .052), mainly driven by reduction in complications in women (12.3% vs 3.2%; P = .034) but not in men (2.8% vs 2.4%; P = 1)., Conclusion: In this cohort of S-ICD patients, women had a higher rate of post-S-ICD pocket-related complications that could be explained by sex-based differences in anatomy., Competing Interests: Disclosures V.J. received funding from the Katz foundation. B.R.R. received funding from NIH and AHRQ. D.B.D. is a consultant for Boston Scientific, Abbott, and AtriCure. M.S.L. is a consultant for Medtronic and Boston Scientific. M.F.E. is a consultant for Medtronic and Boston Scientific., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Background: Advances in leadless pacemaker technology have enabled accelerometer-based atrioventricular (AV) synchronous pacing by sensing atrial mechanical contraction., Objective: The purpose of this study was to report the performance of the Micra AV leadless pacemaker from the worldwide Micra AV post-approval registry (PAR) through 12 months., Methods: The Micra AV PAR is a prospective, single-arm, observational registry designed to assess the safety and effectiveness of Micra AV in a real-world setting. For the present interim analysis, major complications and system revisions through 12 months were summarized and compared to a historical cohort of 2667 patients implanted with a transvenous dual-chamber pacing system., Results: The device was successfully implanted in 796 of 801 patients (99.4%) at 97 centers in 19 countries. Micra AV patients were older (74.1 years vs 71.1 years; P < .0001) with a higher incidence of renal disease (22.3% vs 9.8%; P < .0001) compared with transvenous dual-chamber patients. Through 12 months, the major complication rate was 3.7% in Micra AV patients compared with 8.8% in transvenous dual-chamber patients (hazard ratio 0.42; 95% confidence interval 0.28-0.61; P < .001). The system revision rate was 1.5% in Micra AV patients compared with 5.5% for transvenous dual-chamber patients (hazard ratio 0.25; 95% confidence interval 0.13-0.47; P < .001); this reduction was largely driven by the absence of lead dislodgments requiring revision. The median AV synchrony index was 79.4% (interquartile range 65.2%-86.4%) in patients paced >90%., Conclusion: The Micra AV leadless pacemaker was implanted with a high rate of success in patients with multiple comorbidities, with a significantly lower rate of complications and system revisions through 12 months compared to a historical cohort of patients with transvenous dual-chamber pacemakers., Competing Interests: Disclosures Dr Garweg has received consultant/speaker fees and research grants from Abbott, Biotronik, and Medtronic. Dr Chinitz has received consulting fees from Medtronic, Boston Scientific, and Biosense Webster and speaking/teaching honorarium fees from Boston Scientific and Biotronik. Dr Marijon has received consulting fees from Medtronic, Abbott, and Boston Scientific. Dr Haeberlin has received travel fees/educational grants from Medtronic, Biotronik, Abbott, and Philips/Spectranetics without impact on personal remuneration and works as a proctor for Medtronic. Dr El-Chami serves as a consultant for Medtronic, Boston Scientific, and Biotronik. Dr Roberts has received honoraria from Medtronic, Boston Scientific, and Abbott and research funding from Boston Scientific. Dr Piccini has received clinical research grants from Abbott and Philips and serves as a consultant for Abbott, Boston Scientific, Medtronic, and Philips. Drs Stromberg and Fagan are employees/shareholders of Medtronic. Dr Clementy has received consulting fees from Medtronic. The remaining authors have nothing to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Lead-related venous stenosis and occlusion can complicate the insertion or replacement of transvenous leads in patients with cardiac implantable electronic devices (CIEDs). A possible solution is to tunnel the lead from the contralateral vasculature to the ipsilateral generator. Procedural complications and long-term outcomes remain unclear with this technique., Objective: We sought to assess outcomes of tunneled transvenous leads., Methods: We retrospectively identified all patients who underwent transvenous CIED lead tunneling to a contralateral pocket at our institution between 2014 and 2024. Clinical characteristics, indications for lead implantation, postoperative complications, and long-term outcomes were collected., Results: We identified that 27 patients underwent transvenous lead tunneling at our institution. Most patients were men (20, 74%) with a mean age of 68.8 ± 18.3 years. Most patients had nonischemic cardiomyopathy (16, 59%) with a mean ejection fraction of 29.3% ± 11.3%. The tunneled leads were coronary sinus leads (20, 74%), followed by defibrillator leads (5, 18.5%) and right ventricular pacing leads (2, 7.4%). Implantation procedures were primarily for device upgrade (18), lead revisions (8), or de novo lead placement (1). No postoperative complications were seen. Patients were followed for a mean of 2.2 ± 1.4 years. One tunneled defibrillator lead (3.7%) had low shock impedance 3 years after implantation, which was monitored and did not require an intervention., Conclusion: In patients with ipsilateral venous occlusion, contralateral lead tunneling appears to be an effective and safe approach to manage patients with CIEDs and occluded ipsilateral subclavian veins., Competing Interests: Disclosures Dr El-Chami is a consultant for Medtronic and Boston Scientific. The rest of the authors report no conflicts of interest., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Data on transvenous (TV) lead-associated superior vena cava (SVC) syndrome are limited. The management of this problem might require a multidisciplinary approach, often involving transvenous lead extraction (TLE) followed by angioplasty and stenting., Objective: The purpose of this study was to describe the management and outcome of TV lead-associated SVC syndrome., Methods: We retrospectively identified patients with a diagnosis of SVC syndrome and TV leads at Emory Healthcare between 2015 and 2023., Results: Fifteen patients with lead-related SVC syndrome were identified. The cohort average age was 50 years. Symptoms included swelling of the face, neck, and upper extremities (67%); shortness of breath (53%); and lightheadedness (40%). Patients had an average of 2 ± 0.7 leads crossing the SVC, with a lead dwell time of 9.8 ± 7.5 years. Thirteen patients were managed with TLE, followed by SVC stenting and angioplasty in 10 and angioplasty alone in 2; 1 patient had no intervention after TLE. One patient was managed with anticoagulation, and another had angioplasty and stenting with lead jailing. One patient experienced SVC perforation and cardiac tamponade during SVC stenting, which was managed successfully with a covered stent and pericardiocentesis. Among the 12 patients with TLE and angioplasty ± stenting, 7 underwent reimplantation of a transvenous lead. Two of those patients had symptoms recurrence, and none of the 5 patients without lead reimplantation had recurrence of symptoms., Conclusion: Lead-related SVC syndrome management requires a multidisciplinary approach often including TLE followed by angioplasty and stenting. Avoiding TV lead reimplantation might help reduce symptoms recurrence., Competing Interests: Disclosures Dr El-Chami is a consultant for Medtronic and Boston Scientific. All other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: Cardiac implantable electronic device (CIED) infections are a burden to hospitals and costly for healthcare systems. Chronic kidney disease (CKD) increases the risk of CIED infections, but its differential impact on healthcare utilization, costs, and outcomes is not known., Methods and Results: This retrospective analysis used de-identified Medicare Fee-for-Service claims to identify patients implanted with a CIED from July 2016 to December 2020. Outcomes were defined as hospital days and costs within 12 months post-implant, post-infection CKD progression, and mortality. Generalized linear models were used to calculate results by CKD and infection status while controlling for other comorbidities, with differences between cohorts representing the incremental effect associated with CKD. A total of 584 543 patients had a CIED implant, of which 26% had CKD and 1.4% had a device infection. The average total days in hospital for infected patients was 23.5 days with CKD vs. 14.5 days (P < 0.001) without. The average cost of infection was $121 756 with CKD vs. $55 366 without (P < 0.001), leading to an incremental cost associated with CKD of $66 390. Infected patients with CKD were more likely to have septicaemia or severe sepsis than those without CKD (11.0 vs. 4.6%, P < 0.001). After infection, CKD patients were more likely to experience CKD progression (hazard ratio 1.26, P < 0.001) and mortality (hazard ratio 1.89, P < 0.001)., Conclusion: Cardiac implantable electronic device infection in patients with CKD was associated with more healthcare utilization, higher cost, greater disease progression, and greater mortality compared to patients without CKD., Competing Interests: Conflict of interest: D.J.W. has received research grants and consultancy fees from Medtronic and Boston Scientific and educational fees from Abbot. M.E.T. has received speaker’s fees from Abbot, Biotronik, Boston Scientific, Medtronic, and Microport CRM. J.Z., C.W., R.H., and J.M. are employees of Medtronic, Inc. M.F.E.-C. has received consultant fees from Medtronic and Boston Scientific., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Leadless pacemakers (LPs) capable of VDD pacing allow for atrioventricular synchrony through mechanical sensing of atrial contraction. However, mechanical sensing is less reliable and less predictable than electrical sensing., Objective: The purpose of this study was to evaluate P-wave amplitude during sinus rhythm from preoperative 12-lead electrocardiograms (ECGs) as a predictor for atrial mechanical sensing in patients undergoing VDD LP implantation., Methods: Consecutive patients undergoing VDD LP implantation were included in this 2-center prospective cohort study. ECG parameters were evaluated separately and in combination for association with the signal amplitude of atrial mechanical contraction (A4)., Results: Eighty patients (median age 82 years; female 55%; mean body mass index [BMI] 25.8 kg/m 2 ) were included in the study and 61 patients in the A4 signal analysis (19 patients in VVI mode during follow-up). Absolute (aVL, aVF, V 1 , V 2 ) and BMI-adjusted (I, II, aVL, aVF, aVR, V 1 , V 2 ) P-wave amplitudes from baseline ECGs demonstrated a statistically significant positive correlation with A4 signal amplitude (all P <.05). A combined P-wave signal amplitude of at least 0.2 mV in V 1 and aVL was predictive, with specificity of 83% (95% confidence interval 67%-100%) for A4 signal ≥1 m/s 2 . We found a significant correlation of A4 signal amplitude and overall atrioventricular synchrony (P = .013)., Conclusion: P-wave amplitudes in ECG leads aVL and V 1 can predict A4 signal amplitude in patients with VDD LP and therefore the probability of successful AV synchronous pacing., Competing Interests: Disclosures Dr Hofer reports educational grants, consultant or speaker fees, and fellowship support from Abbott, Medtronic, Biotronik, Boston Scientific, Biosense Webster, Novartis, Bayer, Pfizer, and Spectranetics. Dr Breitenstein has received consultant and/or speaker fees from Abbott, Bayer Healthcare, Biosense Webster, Biotronik, Boston Scientific, Bristol-Myers Squibb, Cook Medical, Daiichi Sankyo, Medtronic, Pfizer, and Spectranetics/Philipps. Dr Steffel has received consultant and/or speaker fees from Abbott, Alexion, Astra-Zeneca, Bayer, Berlin-Chemie, Biosense Webster, Biotronik, Boehringer-Ingelheim, Boston Scientific, BMS, Daiichi Sankyo, Medscape, Medtronic, Menarini, Merck/MSD, Organon, Pfizer, Saja, Servier, and WebMD; and reports ownership of Swiss EP and CorXL. Dr Haeberlin has received travel fees/educational grants from Medtronic, Biotronik, Abbott, and Philips/Spectranetics without impact on his personal remuneration; serves as a proctor for Medtronic; has received research grants from the Swiss National Science Foundation, Swiss Innovation agency Innosuisse, Swiss Heart Foundation, University of Bern, University Hospital Bern, Velux Foundation, Hasler Foundation, Swiss Heart Rhythm Foundation, and Novartis Research Foundation; and is co-founder and CEO of Act-Inno AG. Dr Steinwender has received consultant and/or speaker fees from Medtronic, Biotronik, Abbott, Boston Scientific, and Microport; and serves as a proctor for Medtronic. Dr Saguner received educational grants through his institution from Abbott, Bayer Healthcare, Biosense Webster, Biotronik, Boston Scientific, BMS/Pfizer, and Medtronic; and speaker/advisory board/consulting fees from Bayer Healthcare, Biotronik, Daiichi-Sankyo, Medtronic, Novartis, Pfizer, Stride Bio Inc, and Zoll. He has stock options from Gilead Sciences. Dr El-Chami is a consultant for Medtronic and Boston Scientific. All other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Early guidance recommended a bolus of intravenous heparin at the beginning of leadless pacemaker (LP) implantation procedures. However, due to concern about bleeding complications, more recent practice has tended toward omitting the bolus and only running a continuous heparin infusion through the introducer sheath. The impact of omitting the heparin bolus on procedural outcomes is not clear., Methods: We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. The decision to bolus with heparin was at operator discretion., Results: Among 621 LP implants, 326 received an intravenous heparin bolus, 243 did not, and 52 patients were excluded because heparin bolus status could not be confirmed. There was a trend toward more frequent omission of the heparin bolus with more recent implants. Median follow-up after LP implant was 14.3 (interquartile range [IQR]: 8.4-27.9) months. There was no difference between heparin bolus and no bolus groups in the number of device deployments/recaptures (1.42 ± 0.81 vs. 1.31 ± 0.66, p = .15). Implant-related adverse events were also similar between heparin bolus and no bolus groups: access-site hematoma requiring intervention (7 vs. 5, p = .99), pseudoaneurysm (1 vs. 1, p = .99), cardiac perforation (1 vs. 1, p = .99), intraprocedural device thrombus formation (2 vs. 4, p = .41), 30-day rehospitalization (21 vs. 15, p = .98), and 30-day all-cause mortality (16 vs. 14, p = .70). There was one additional nonfatal cardiac perforation in a patient who was excluded due to unknown heparin bolus status. Regarding device electrical parameters between heparin bolus and no bolus groups, there were no significant differences at the time of implant: pacing capture threshold 0.5 ± 0.4 vs. 0.5 ± 0.3, p = .10; pacing impedance 739.9 ± 226.4 vs. 719.1 ± 215.4, p = .52; R wave sensing 11.7 ± 5.7 vs. 12.0 ± 5.4, p = .34). Long-term device performance was also similar between groups., Conclusion: Omission of the systemic heparin bolus at the time of LP implantation appears safe in appropriately selected patients. Heparin bolus may still be considered in long cases requiring multiple device deployments or in patients at high risk for thrombotic complications., (© 2024 Wiley Periodicals LLC.)

Background: The PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events., Objective: This prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias., Methods: This multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm., Results: In total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13-279.95; P < .001)., Conclusion: A PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure., Competing Interests: Disclosures Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cardiac and has stock options from AtaCor Medical Inc. Dr El-Chami reports consultancy fees from Medtronic and Boston Scientific. Dr Marquie reports consultancy fees from Boston Scientific.Dr Tilz reports consultancy fees from Boston Scientific, Biotronik, Biosense Webster, and Abbott Medical; speaker’s honoraria from Boston Scientific, Biotronik, Biosense Webster, Abbott Medical, and LifeTech; and research grants from Abbott, Biosense Webster, and LifeTech. Dr Lambiase reports research contracts with Boston Scientific and is a member of the advisory board of Boston Scientific. Dr Manyam reports consultancy fees from Janssen and Abbott. Dr Betts received honoraria for speaking and proctoring from Boston Scientific. Dr Bijsterveld presented at a conference of Abbott and gave a presentation sponsored by AstraZeneca. Dr Field reports being a speaker and proctor for Boston Scientific. Dr Golovchiner reports being a proctor for Boston Scientific. Dr de Jong reports consultancy fees from Medtronic. Dr Lewis reported to receive travel grants and honoraria from Abbott, Boston Scientific, and Medtronic. Dr Martin reported to receive research grants, honoraria, and speaker’s fees from Boston Scientific and honoraria and speaker’s fees from Medtronic and Biosense Webster. Dr Miller reported to receive consultancy fees from Boston Scientific. Dr Shaik reported to receive consultancy fees from Boston Scientific, Medtronic, and Biotronik. Dr Kuschyk reported to receive consultancy fees and honoraria from Boston Scientific, consultancy fees from Impulse Dynamics, and honoraria fees from Medtronic. Dr Boveda reported to receive consultancy fees from Medtronic, Boston Scientific, MicroPort, and Zoll. Dr Kaiser is a proctor for Boston Scientific. Dr Maass reported to receive consultancy fees from Boston Scientific and Medtronic, with all fees going to the department of Cardiology of the University Medical Center Groningen. Dr Wilde is a consultant for ARMGO and Thyrvv Therapeutics. The rest of the authors report no conflicts of interest., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) is one of the most common complications after cardiac surgery. New-onset post-operative AF may signal an elevated risk of AF and associated outcomes in long-term follow-up. We aimed to estimate the rate of AF recurrence as detected by an implantable loop recorder (ILR) in patients experiencing post-operative AF within 30 days after cardiac surgery., Methods: We searched MEDLINE, Embase and Cochrane CENTRAL to April 2023 for studies of adults who did not have known AF, experienced new-onset AF within 30 days of cardiac surgery and received an ILR. We pooled individual participant data on timing of AF recurrence using a random-effects model with a frailty model applied to a Cox proportional hazard analysis., Results: From 8671 citations, 8 single-centre prospective cohort studies met eligibility criteria. Data were available from 185 participants in 7 studies, with a median follow-up of 1.7 (IQR: 1.3-2.8) years. All included studies were at a low risk of bias. Pooled AF recurrence rates following 30 post-operative days were 17.8% (95% CI 11.9%-23.2%) at 3 months, 24.4% (17.7%-30.6%) at 6 months, 30.1% (22.8%-36.7%) at 12 months and 35.3% (27.6%-42.2%) at 18 months., Conclusions: In patients who experience new-onset post-operative AF after cardiac surgery, AF recurrence lasting at least 30 s occurs in approximately 1 in 3 in the first year after surgery. The optimal frequency and modality to use for monitoring for AF recurrence in this population remain uncertain., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose of Review: Tricuspid regurgitation is a commonly encountered valvular pathology in patients with trans-tricuspid pacing or implantable cardioverter-defibrillator leads. Transcatheter tricuspid valve interventions are increasingly performed in patients at high surgical risk. Implantation of these valves can lead to the "jailing" of a trans-tricuspid lead. This practice carries both short- and long-term risks of lead failure and subsequent infection without the ability to perform traditional transvenous lead extraction. Herein, this manuscript reviews available therapeutic options for lead management in patients undergoing transcatheter tricuspid valve interventions., Recent Findings: The decision to jail a lead may be appropriate in certain high-risk cases, though extraction may be a better option in most cases given the variety of options for re-implant, including leadless pacemakers, valve-sparing systems, epicardial leads, leads placed directly through prosthetic valves, and the completely subcutaneous implantable-defibrillator. A growing number of patients meet the requirement for CIED implantation in the United States. A significant proportion of these patients will have tricuspid valve dysfunction, either related to or independent of their transvenous lead. As with any percutaneous intervention that has shown efficacy, the role of TTVI is also likely to increase as this therapy advances beyond the investigational phase. As such, the role of the heart team in the management of these patients will be increasingly critical in the years to come, and in those patients that have pre-existing CIED leads, we advocate for the involvement of an electrophysiologist in the heart team., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Introduction: Transvenous leads have been implicated in tricuspid valve (TV) dysfunction, but limited data are available regarding the effect of extracting leads across the TV on valve regurgitation. The aim of this study is to quantify tricuspid regurgitation (TR) before and after lead extraction and identify predictors of worsening TR., Methods: We studied 321 patients who had echocardiographic data before and after lead extraction. TR was graded on a scale (0 = none/trivial, 1 = mild, 2 = moderate, 3 = severe). A change of >1 grade following extraction was considered significant., Results: A total of 321 patients underwent extraction of a total of 338 leads across the TV (1.05 ± 0.31 leads across the TV per patient). There was no significant difference on average TR grade pre- and postextraction (1.18 ± 0.91 vs. 1.15 ± 0.87; p = 0.79). TR severity increased after extraction in 84 patients, but was classified as significantly worse (i.e., >1 grade change in severity) in only 8 patients (2.5%). Use of laser lead extraction was associated with a higher rate of worsening TR postextraction (44.0% vs. 31.6%, p = 0.04)., Conclusion: In our single-center analysis, extraction of leads across the TV did not significantly affect the extent of TR in most patients. Laser lead extraction was associated with a higher rate of worsening TR after extraction., (© 2024 Wiley Periodicals LLC.)

Background and Aims: Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed., Methods: All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models., Results: 1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001)., Conclusions: Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

The American Heart Association sponsored the first iteration of a scientific statement that addressed all aspects of cardiovascular implantable electronic device infection in 2010. Major advances in the prevention, diagnosis, and management of these infections have occurred since then, necessitating a scientific statement update. An 11-member writing group was identified and included recognized experts in cardiology and infectious diseases, with a career focus on cardiovascular infections. The group initially met in October 2022 to develop a scientific statement that was drafted with front-line clinicians in mind and focused on providing updated clinical information to enhance outcomes of patients with cardiovascular implantable electronic device infection. The current scientific statement highlights recent advances in prevention, diagnosis, and management, and how they may be incorporated in the complex care of patients with cardiovascular implantable electronic device infection.

Background: The Micra AV Coverage with Evidence Development study is a novel analysis of utilization and outcomes associated with Micra AV leadless pacing in US Medicare patients., Objective: The purpose of this study was to describe patient characteristics, complications, and outcomes of patients implanted with a Micra AV leadless pacemaker compared with a contemporaneous cohort of patients implanted with a dual chamber transvenous pacemaker., Methods: Patients implanted with Micra AV (n = 7471) or a dual chamber transvenous pacemaker (n = 107,800) from February 5, 2020, through December 1, 2021, were identified using device registry-linked Medicare claims data. Acute complications were assessed at 30 days, and chronic complications, reinterventions, and all-cause mortality were assessed at 6 months., Results: Patients implanted with Micra AV had higher rates of end-stage renal disease (14.9% vs 2.0%; P < .0001) and overall comorbidity burden (mean Charlson Comorbidity Index 4.9 vs 3.8; P < .0001). There was no difference in the unadjusted rate of complications at 30 days (9.1% vs 8.7%; P = .61), and patients implanted with Micra AV had a significantly lower adjusted rate of complications (8.6% vs 11.0%; P < .0001). At 6 months, patients implanted with Micra AV had significantly lower rates of complications (adjusted hazard ratio 0.50; 95% confidence interval 0.43-0.57; P < .0001) and reinterventions (adjusted hazard ratio 0.46; 95% confidence interval 0.36-0.58; P < .0001). Patients implanted with Micra AV had higher all-cause mortality at 30 days and 6 months, likely because of differences in the underlying risk of mortality., Conclusion: Patients implanted with Micra AV had similar rates of complications at 30 days and significantly lower rates of complications and reinterventions at 6 months, despite being sicker than patients implanted with a transvenous pacemaker., Competing Interests: Disclosures Dr Crossley is supported by CTSA award no. UL1 TR002243 from the National Center for Advancing Translational Sciences; consults for Medtronic and Boston Scientific; and serves on the speakers bureau for Medtronic and Spectranetics. Dr Piccini is supported by R01HL128595 from the National Heart, Lung, and Blood Institute; receives research grants from Abbott, American Heart Association, the Association for the Advancement of Medical Instrumentation, Bayer, Boston Scientific, and Philips; and consults for Abbott, AbbVie, Ablacon, AltaThera, ARCA Biopharma, Biotronik, Boston Scientific, Bristol-Myers Squibb, LivaNova, Medtronic, Milestone, ElectroPhysiology Frontiers, Itamar, Pfizer, Sanofi, Philips, ResMed, and UpToDate. Dr El-Chami consults for Medtronic, Boston Scientific, and Biotronik. Dr Longacre, Dr Higuera, Mr Stromberg, and Dr Cheng are employees and shareholders of Medtronic., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Declaration of Competing Interest The authors have no competing interests to declare.

Aims: Single-connector (DF4) defibrillator leads have become the predominantly implanted transvenous implantable cardioverter-defibrillator lead. However, data on their long-term performance are derived predominantly from manufacturer product performance reports., Methods and Results: We reviewed medical records in 5289 patients with DF4 leads between 2011 and 2023 to determine the frequency of lead-related abnormalities. We defined malfunction as any single or combination of electrical abnormalities requiring revision including a sudden increase (≥2×) in stimulation threshold, a discrete jump in high-voltage impedance, or sensing of non-physiologic intervals or noise. We documented time to failure, predictors of failure, and management strategies. Mean follow-up after implant was 4.15 ± 3.6 years (median = 3.63), with 37% of leads followed for >5 years. A total of 80 (1.5%) leads demonstrated electrical abnormalities requiring revision with an average time to failure of 4 ± 2.8 years (median = 3.5). Of the leads that malfunctioned, 62/80 (78%) were extracted and replaced with a new lead and in the other 18 cases, malfunctioned DF4 leads were abandoned, and a new lead implanted. In multivariable models, younger age at implant (OR 1.03 per year; P < 0.001) and the presence of Abbott/St. Jude leads increased the risk of malfunction., Conclusion: DF4 defibrillator leads demonstrate excellent longevity with >98.3% of leads followed for at least 5 years still functioning normally. Younger age at implant and lead manufacturer are associated with an increased risk of DF4 lead malfunction. The differences in lead survival between manufacturers require further investigation., Competing Interests: Conflict of interest:  A.d.S.: honoraria/speaking/consulting fee—Baylis Medical Company. M.S.L.: honoraria/speaking/consulting fee—Medtronic; Boston Scientific. D.B.D.L.: honoraria/speaking/consulting fee—Boston Scientific; Medtronic; AtriCure, Inc. A.M.P.: honoraria/speaking/consulting fee—Biosense Webster, Inc. M.F.E.-C.: honoraria/speaking/consulting fee—Boston Scientific; Medtronic. The rest of the authors have no disclosures, (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: The mechanisms of transition from regular rhythms to ventricular fibrillation (VF) are poorly understood. The concordant to discordant repolarization alternans pathway is extensively studied; however, despite its theoretical centrality, cannot guide ablation. We hypothesize that complex repolarization dynamics, i.e. oscillations in the repolarization phase of action potentials with periods over two of classic alternans, is a marker of electrically unstable substrate, and ablation of these areas has a stabilizing effect and may reduce the risk of VF. To prove the existence of higher-order periodicities in human hearts., Methods and Results: We performed optical mapping of explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Signals recorded from the right ventricle endocardial surface were processed to detect global and local repolarization dynamics during rapid pacing. A statistically significant global 1:4 peak was seen in three of six hearts. Local (pixel-wise) analysis revealed the spatially heterogeneous distribution of Periods 4, 6, and 8, with the regional presence of periods greater than two in all the hearts. There was no significant correlation between the underlying restitution properties and the period of each pixel., Conclusion: We present evidence of complex higher-order periodicities and the co-existence of such regions with stable non-chaotic areas in ex vivo human hearts. We infer that the oscillation of the calcium cycling machinery is the primary mechanism of higher-order dynamics. These higher-order regions may act as niduses of instability and may provide targets for substrate-based ablation of VF., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Same-day discharge (SDD) after cardiovascular procedures is rapidly gaining ground., Objective: We sought to evaluate the safety of SDD after transvenous lead extraction (TLE)., Methods: We performed a retrospective chart review of patients who underwent elective TLE between January 2020 and October 2021 at our institution. The primary outcome was SDD, and major procedural complications and readmissions within 30 days of the procedure were secondary outcomes., Results: In this analysis of 111 patients who underwent elective TLE, 80 patients (72%) were discharged on the same day (SDD group) while 31 patients (28%) stayed overnight (overnight group). Lead malfunction was the most common indication for TLE in both groups. Patients in the overnight group were more likely to have a lead dwell time of ≤10 years than those in the SDD group (38.7% vs 20% of all leads in each group; P = .042), have laser sheaths used for extraction and a higher number of leads extracted. No major complications were reported in both groups. In a multivariate analysis, lower body mass index and the use of laser sheath during TLE were predictors of overnight stay. Patients who underwent a procedure using advanced extraction techniques were 3.5 times more likely to stay overnight (95% confidence interval 1.27-9.78; P = .016)., Conclusion: In appropriately selected patients undergoing elective lead extraction, SDD is feasible and safe. Higher body mass index, fewer extracted leads, shorter lead dwell times (<10 years), and less frequent use of laser-powered extraction sheaths were associated with an increased likelihood of SDD., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Scarce data exist on the evolution of device-related thrombus (DRT) after left atrial appendage closure (LAAC)., Objectives: This study sought to assess the incidence, predictors, and clinical impact of persistent and recurrent DRT in LAAC recipients., Methods: Data were obtained from an international multicenter registry including 237 patients diagnosed with DRT after LAAC. Of these, 214 patients with a subsequent imaging examination after the initial diagnosis of DRT were included. Unfavorable evolution of DRT was defined as either persisting or recurrent DRT., Results: DRT resolved in 153 (71.5%) cases and persisted in 61 (28.5%) cases. Larger DRT size (OR per 1-mm increase: 1.08; 95% CI: 1.02-1.15; P = 0.009) and female (OR: 2.44; 95% CI: 1.12-5.26; P = 0.02) were independently associated with persistent DRT. After DRT resolution, 82 (53.6%) of 153 patients had repeated device imaging, with 14 (17.1%) cases diagnosed with recurrent DRT. Overall, 75 (35.0%) patients had unfavorable evolution of DRT, and the sole predictor was average thrombus size at initial diagnosis (OR per 1-mm increase: 1.09; 95% CI: 1.03-1.16; P = 0.003), with an optimal cutoff size of 7 mm (OR: 2.51; 95% CI: 1.39-4.52; P = 0.002). Unfavorable evolution of DRT was associated with a higher rate of thromboembolic events compared with resolved DRT (26.7% vs 15.1%; HR: 2.13; 95% CI: 1.15-3.94; P = 0.02)., Conclusions: About one-third of DRT events had an unfavorable evolution (either persisting or recurring), with a larger initial thrombus size (particularly >7 mm) portending an increased risk. Unfavorable evolution of DRT was associated with a 2-fold higher risk of thromboembolic events compared with resolved DRT., Competing Interests: Funding Support and Author Disclosures Dr Rodés-Cabau holds the Research Chair “Fondation Famille Jacques Larivière” for the Development of Structural Heart Disease Interventions (Laval University, Quebec City, Canada). He also has received institutional research grants from Boston Scientific. Dr Maarse has received an unrestricted grant from Boston Scientific. Dr Pérez de Prado has served as a proctor for Boston Scientific. Dr Gupta has served as a proctor for Abbott. Dr Sanchez has served as a speaker and proctor for Boston Scientific. Dr Wang has served as a consultant for Edwards Lifesciences, Boston Scientific, and Neochord; and received research grant support from Boston Scientific assigned to his employer, the Henry Ford Health System. Dr Demkow has served as a proctor for Abbott and Boston Scientific. Dr Alkhouli has served as a consultant for Boston Scientific. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Introduction: Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions., Methods: This retrospective study included patients who received a Micra VR (Micra TM MC1VR01) or Micra AV (Micra TM MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up., Results: A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 ± 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 ± 1.1 years: 1.6 ± 1.3 years for the Micra VR group and 0.8 ± 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% ± 37.2% postprocedure vs. 47.7% ± 40.6% at last follow-up, p < .001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% ± 10.6% vs. 51.5% ± 11.2% p < .001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% ± 11.9% vs. 48.8% ± 11.9%, p = .003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% ± 9.0% vs. 54.6% ± 9.7%, p = .06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction., Conclusion: Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort., (© 2023 Wiley Periodicals LLC.)

Competing Interests: Disclosures Dr Hoskins is a consultant for Boston Scientific and Abbott Medical; Drs Greenbaum and Babaliaros have received institutional research support from Abbott Vascular, Ancora Heart, Edwards Lifesciences, Gore Medical, JenaValve, Medtronic, Polares Medical, Transmural Systems, and 4C Medical; have received consulting fees from Abbott Vascular, Edwards Lifesciences, and Medtronic; and have an equity interest in Transmural Systems. Dr Lloyd is a consultant for Medtronic and Boston Scientific. Drs Gleason, Byku, Greenbaum, and Babaliaros have institutional research contracts for clinical investigation of transcatheter aortic, mitral, and tricuspid devices from Edwards Lifesciences, Abbott Vascular, Medtronic, and Boston Scientific. Dr El-Chami is a consultant for Boston Scientific, Medtronic and Biotronik. Dr Lederman is coinventor on patents assigned to the National Institutes of Health, for electrosurgical devices including for septal reduction therapy. The other authors report no conflicts.

Background: Continuous automatic optimisation of cardiac resynchronisation therapy (CRT), stimulating only the left ventricle to fuse with intrinsic right bundle conduction (synchronised left ventricular stimulation), might offer better outcomes than conventional CRT in patients with heart failure, left bundle branch block, and normal atrioventricular conduction. This study aimed to compare clinical outcomes of adaptive CRT versus conventional CRT in patients with heart failure with intact atrioventricular conduction and left bundle branch block., Methods: This global, prospective, randomised controlled trial was done in 227 hospitals in 27 countries across Asia, Australia, Europe, and North America. Eligible patients were aged 18 years or older with class 2-4 heart failure, an ejection fraction of 35% or less, left bundle branch block with QRS duration of 140 ms or more (male patients) or 130 ms or more (female patients), and a baseline PR interval 200 ms or less. Patients were randomly assigned (1:1) via block permutation to adaptive CRT (an algorithm providing synchronised left ventricular stimulation) or conventional biventricular CRT using a device programmer. All patients received device programming but were masked until procedures were completed. Site staff were not masked to group assignment. The primary outcome was a composite of all-cause death or intervention for heart failure decompensation and was assessed in the intention-to-treat population. Safety events were collected and reported in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT02205359, and is closed to accrual., Findings: Between Aug 5, 2014, and Jan 31, 2019, of 3797 patients enrolled, 3617 (95·3%) were randomly assigned (1810 to adaptive CRT and 1807 to conventional CRT). The futility boundary was crossed at the third interim analysis on June 23, 2022, when the decision was made to stop the trial early. 1568 (43·4%) of 3617 patients were female and 2049 (56·6%) were male. Median follow-up was 59·0 months (IQR 45-72). A primary outcome event occurred in 430 of 1810 patients (Kaplan-Meier occurrence rate 23·5% [95% CI 21·3-25·5] at 60 months) in the adaptive CRT group and in 470 of 1807 patients (25·7% [23·5-27·8] at 60 months) in the conventional CRT group (hazard ratio 0·89, 95% CI 0·78-1·01; p=0·077). System-related adverse events were reported in 452 (25·0%) of 1810 patients in the adaptive CRT group and 440 (24·3%) of 1807 patients in the conventional CRT group., Interpretation: Compared with conventional CRT, adaptive CRT did not significantly reduce the incidence of all-cause death or intervention for heart failure decompensation in the included population of patients with heart failure, left bundle branch block, and intact AV conduction. Death and heart failure decompensation rates were low with both CRT therapies, suggesting a greater response to CRT occurred in this population than in patients in previous trials., Funding: Medtronic., Competing Interests: Declaration of interests BLW reports participating in physician advisory committees of Medtronic, Abbott, Boston Scientific, Biotronik, and Philips, and receiving honoraria from Medtronic, Abbott, Boston Scientific, Biotronik, Philips, and Cook. GF reports receiving lecture fees, participating in committees of trials sponsored by Bayer, Boehringer Ingelheim, Novartis, Servier, Vifor, Impulse Dynamics, and Medtronic, and receiving research grants from the European Union. CL reports participating in a Medtronic advisory board and receiving honoraria from Medtronic, Biotronik, LivaNova, Boston Scientific, and Abbott. MRG reports being a consultant for Medtronic and Boston Scientific and receiving honoraria from Medtronic, Boston Scientific, and EBR Systems. KK reports receiving speaker's honoraria and research grants from Medtronic Japan and Biotronik Japan. GMF reports receiving research grants from the National Heart, Lung, and Blood Institute, American Heart Association, Amgen, Bayer, Bristol Myers Squibb, Merck, Cytokinetics, and CSL-Behring, acting as a consultant for Novartis, Amgen, Bristol Myers Squibb, Cytokinetics, Cardionomic, Boehringer-Ingelheim, American Regent, Abbott, AstraZeneca, Regeneron, Reprieve, Myovant, Sequana, Windtree Therapuetics, Rocket Pharma, and Whiteswell, and serving on clinical endpoint committees or data safety monitoring boards for Amgen, Merck, Medtronic, EBR Systems, V-Wave, and LivaNova. MFE-C reports consultancy work for Medtronic and Boston Scientific. VE reports receiving support from a Clinical Research Scholar Award from the Fonds de recherche du Québec-Santé (FRQS) and honoraria from Abbott, Boston Scientific, and Medtronic. BP reports consultancy work for Abbott, Biotronik, Boston Scientific, and Microport, and receiving honoraria from Medtronic. FP reports receiving research grants from Medtronic, Boston Scientific, and Abbott. ESC reports consultancy work for Medtronic, Abbott, Intershunt, and Cardionomic, and serving on data safety monitoring boards and clinical events committees for LivaNova, EBR, and Abbott. BB reports consultancy work for Medtronic, Boston Scientific, and Pfizer. HHE reports receiving research grants from Medtronic. NV reports consultancy work for Medtronic, Abbott, Biotronik, Boston Scientific, EP Solutions, Implicity, and Pacemate. JvW, BG, DES, and DHF report being employees of Medtronic. DB reports being a mid-career investigator (supported by the Heart and Stroke Foundation of Ontario and the University of Ottawa Chair in Electrophysiology Research) and receiving research funding from Medtronic, Boston Scientific, Boehringer Ingelheim, Bayer, Biotronik, Pfizer, and Bristol Myers Squibb. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up., Objectives: The S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers., Methods: Patients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals., Results: A total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD-related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%., Conclusions: In the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618)., Competing Interests: Funding Support and Author Disclosures This study was sponsored by Boston Scientific. Dr Gold has received consulting fees from Boston Scientific and Medtronic; and has participated in clinical trials with Boston Scientific, Medtronic, and Abbott. Dr El-Chami has received compensation for services from Boston Scientific and Medtronic. Dr Burke has received honoraria and research grants from AtaCor Medical, Biosense Webster, and Boston Scientific; and has held equity in AtaCor Medical. Dr Upadhyay has served on advisory boards at Abbott, BioTel, Biotronik, and Medtronic; and has served a speaker for Zoll Medical. Dr Herre has received research support from Analytics 4 Life, Boston Scientific, and EBR Systems; has received consulting fees from Medtronic; and has served as the Board Chair for LifeNet Health. Dr Kutalek has received consulting fees and compensation for services from Boston Scientific. Dr Knight has received consulting and speaker fees and investigator and/or fellowship support from Abbott, Atricure, Boston Scientific, Biosense Webster, Biotronik, CVRx, and Medtronic. Ms Leigh is a full-time employee of Boston Scientific. Ms Lucas is a full-time employee of NAMSA. Mr Carter is a full-time employee of Boston Scientific. Dr Brisben is a full-time employee of Boston Scientific. Dr Aasbo has received consulting fees from Boston Scientific and Biotronik. Dr Weiss has received compensation for services from Abbott, Boston Scientific, Biosense, Biotronik, S4, and Sanofi; has received research grants from Abbott, Boston Scientific, Biosense, and Medtronic; and has received fellowship support from Abbott, Boston Scientific, Biosense Webster, and Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Class IC antiarrhythmic agents are effective for treating atrial tachyarrhythmias, but their use is restricted in patients with coronary artery disease (CAD). Data on the safety of the use of IC agents in patients with CAD in the absence of recent acute coronary syndromes are lacking., Objectives: This study sought to evaluate the safety and feasibility of treatment with IC agents in patients with varying degrees of CAD in a large serial, real-world cohort., Methods: We retrospectively identified all patients at our institution from January 2005 to February 2021 on a IC agent (n = 3,445) and those on sotalol or dofetilide (n = 2,216) as controls, excluding those with a prior history of ventricular tachycardia, implantable cardioverter-defibrillator placement, or nonrevascularized myocardial infarction. Baseline clinical characteristics included degree of CAD (categorized as none, nonobstructive, or obstructive), other comorbid illness, and medication use. Clinical outcomes, including survival, were ascertained. We performed Cox regression analysis to evaluate the effect of IC use on event-free survival across varying degrees of CAD., Results: After adjustment for baseline characteristics, there was an independent association between IC use and improved mortality. However, there was an interaction between IC use and degree of CAD (compared to sotalol) demonstrating poorer event-free survival among those with obstructive coronary disease (HR: 3.80; 95% CI: 1.67-8.67; P = 0.002)., Conclusions: Among select patients with nonobstructive CAD and without a history of ventricular tachycardia, IC agents are not associated with increased mortality. Therefore, these agents may be an option for some patients in whom they are frequently restricted. Further prospective studies are warranted., Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Introduction: Hemodynamic decompensation during catheter ablation occurs due to prolonged procedure time and irrigant delivery directly into the cardiac chambers. Real-time hemodynamic monitoring of patients undergoing catheter ablation procedures may identify patients at risk of decompensation; we set out to assess the feasibility of a novel, real-time, intracardiac pressure monitoring system using a standard irrigated ablation catheter., Methods: We studied 13 consecutive who underwent pressure measurement of the left atrium (LA) and left ventricle (LV) via transeptal access with a Swan Ganz (SG) catheter followed by two commercially available irrigated ablation catheters. Pressure waveform data was extracted to compare LA peak pressure, LV peak systolic pressure, LV end-diastolic pressure, and waveform analysis., Results: Comparison between the SG and ablation catheters (AblA; AblB) demonstrated that LV systolic pressure (0.61-16.8 mmHg; 1.32-18.2 mmHg), and LV end-diastolic pressure (-3.4 to 2.8 mmHg; -3.0 to 3.35 mmHg) were well correlated and had accepted repeatability. Ablation waveforms demonstrated an 89.9 ± 6.4% correlation compared to SG waveforms., Conclusion: Pressure measurements derived from an irrigated ablation catheter are accurate and reliable when compared to an SG catheter. Further studies are needed to determine how real-time pressure monitoring can improve outcomes during ablation procedures., (© 2023 Wiley Periodicals LLC.)

Introduction: The Micra Coverage with Evidence Development (CED) Study is a novel comparative analysis of Micra (leadless VVI) and transvenous single-chamber ventricular pacemakers (transvenous VVI) using administrative claims data. To compare chronic complications, device reinterventions, heart failure hospitalizations, and all-cause mortality after 3 years of follow-up., Methods: US Medicare claims data linked to manufacturer device registration information were used to identify Medicare beneficiaries with a de novo implant of either a Micra VR leadless VVI or transvenous VVI pacemaker from March 9, 2017 to December 31, 2018. Unadjusted and propensity score overlap-weight adjusted Fine-Gray competing risk models were used to compare outcomes at 3 years., Results: Leadless VVI patients (N = 6219) had a 32% lower rate of chronic complications and a 41% lower rate of reintervention compared with transvenous VVI patients (N = 10 212) (chronic complication hazard ratio [HR] 0.68; 95% confidence interval [CI], 0.59-0.78; reintervention HR 0.59; 95% CI 0.44-0.78). Infections rates were significantly lower among patients with a leadless VVI (<0.2% vs. 0.7%, p < .0001). Patients with a leadless VVI also had slightly lower rates of heart failure hospitalization (HR 0.90; 95% CI 0.84-0.97). There was no difference in the adjusted 3-year all-cause mortality rate (HR 0.97; 95% CI, 0.92-1.03)., Conclusion: This nationwide comparative evaluation of leadless VVI versus transvenous VVI de novo pacemaker implants demonstrated that the leadless group had significantly fewer complications, reinterventions, heart failure hospitalizations, and infections than the transvenous group at 3 years, confirming that the previously reported shorter-term advantages associated with leadless pacing persist and continue to accrue in the medium-to-long-term., (© 2023 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Aims: This study compares clinical outcomes between leadless pacemakers (leadless-VVI) and transvenous ventricular pacemakers (transvenous ventricular permanent-VVI) in subgroups of patients at higher risk of pacemaker complications., Methods and Results: This study is based on the Micra Coverage with Evidence Development (CED) study. Patients from the Micra CED study were considered in a high-risk subgroup if they had a diagnosis of chronic kidney disease Stages 4-5 (CKD45), end-stage renal disease, malignancy, diabetes, tricuspid valve disease (TVD), or chronic obstructive pulmonary disease (COPD) 12 months prior to pacemaker implant. A pre-specified set of complications and reinterventions were identified using diagnosis and procedure codes. Competing risks models were used to compare reinterventions and complications between leadless-VVI and transvenous-VVI patients within each subgroup; results were adjusted for multiple comparisons. A post hoc comparison of a composite outcome of reinterventions and device complications was conducted. Out of 27 991 patients, 9858 leadless-VVI and 12 157 transvenous-VVI patients have at least one high-risk comorbidity. Compared to transvenous-VVI patients, leadless-VVI patients in four subgroups [malignancy, HR 0.68 (0.48-0.95); diabetes, HR 0.69 (0.53-0.89); TVD, HR 0.60 (0.44-0.82); COPD, HR 0.73 (0.55-0.98)] had fewer complications, in three subgroups [diabetes, HR 0.58 (0.37-0.89); TVD, HR 0.46 (0.28-0.76); COPD, HR 0.51 (0.29-0.90)) had fewer reinterventions, and in four subgroups (malignancy, HR 0.52 (0.32-0.83); diabetes, HR 0.52 (0.35-0.77); TVD, HR 0.44 (0.28-0.70); COPD, HR 0.55 (0.34-0.89)] had lower rates of the combined outcome., Conclusion: In a real-world study, leadless pacemaker patients had lower 2-year complications and reinterventions rates compared with transvenous-VVI pacing in several high-risk subgroups., Trial Registration: ClinicalTrials.gov ID NCT03039712., Competing Interests: Conflict of interest: S.B. is a consultant for Medtronic, Boston Scientific, Microport, and Zoll. M.F.E.-C. is a consultant for Medtronic, Boston Scientific and Biotronik. L.H., C.L., C.W., K.W., and K.S. are employees and shareholders of Medtronic., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Introduction: Micra atrioventricular (AV) provides leadless atrioventricular synchronous pacing by sensing atrial contraction (A4 signal). Real-world operation and reliability of AV synchrony (AVS) assessment using device data have not been described. The purposes of this study were to (1) assess the correlation between AVS and atrial mechanical sensed-ventricular pacing (AM-VP) percentages in patients with permanent high-degree AV block and (2) report on the real-world effectiveness of Micra AV., Methods: The correlation between ECG-determined AVS in-clinic and device-collected %AM-VP was assessed using data from 40 patients with high-degree AV block enrolled in the Micra Atrial tRacking using a Ventricular AccELerometer (MARVEL) 2 study. A retrospective analysis to assess continuously-sampled %AM-VP since last session, device programming, and electrical parameters was performed using Micra AV transmissions from the Medtronic CareLink database. Patients with transmissions ≥180 days postimplant were included., Results: Among the 40 MARVEL 2 AV block patients with a median %VP of 99.7%, AVS was highly correlated with AM-VP (median AVS 87.1%, median AM-VP 79.1%; R 2  = 0.764, p < .001). The CareLink cohort included 4384 patients programmed to VDD mode. The mean A4 amplitude was 2.3 ± 1.8 m/s 2 at implant and 2.3 ± 1.6 m/s 2 at 28 weeks. In patients with %VP >90% (n = 1662), the median %AM-VP was 74.7%. For the full cohort, median %VP was 65.6% and median projected battery longevity was 10.5 years., Conclusion: In patients with a high pacing burden, %AM-VP provides a reasonable estimation of AVS. The first large real-world analysis of Micra AV patients with >90% VP showed stable atrial sensing over time with a median %AM-VP, a correlate of AVS, of 74.7%., (© 2022 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Background: Previous studies demonstrated that accelerometer-based, mechanically timed atrioventricular synchrony (AVS) is feasible using a leadless ventricular pacemaker., Objective: The purpose of this study was to determine the performance of a leadless ventricular pacemaker with accelerometer-based algorithms that provide AVS pacing., Methods: AccelAV was a prospective, single-arm study to characterize AVS in patients implanted with a Micra AV, which uses the device accelerometer to mechanically detect atrial contractions and promote VDD pacing. The primary objective was to characterize resting AVS at 1 month in patients with complete atrioventricular block (AVB) and normal sinus function., Results: A total of 152 patients (age 77 ± 11 years; 48% female) from 20 centers were enrolled and implanted with a leadless pacemaker. Among patients with normal sinus function and complete AVB (n = 54), mean resting AVS was 85.4% at 1 month, and ambulatory AVS was 74.8%. In the subset of patients (n = 20) with programming optimization, mean ambulatory AVS was 82.6%, representing a 10.5% improvement (P <.001). Quality of life as measured by the EQ-5D-3L (EuroQol Five-Dimensions Three-Level questionnaire) improved significantly from preimplant to 3 months (P = .031). In 37 patients with AVB at both 1 and 3 months, mean AVS during rest did not differ (86.1% vs 84.1%; P = .43). There were no upgrades to dual-chamber devices or cardiac resynchronization therapy through 3 months., Conclusion: Accelerometer-based mechanical atrial sensing provided by a leadless pacemaker implanted in the right ventricle significantly improves quality of life in a select cohort of patients with AV block and normal sinus function. AVS remained stable through 3 months, and there were no system upgrades to dual-chamber pacemakers., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

The field of cardiac pacing has been defined by constant development to provide efficacious, safe, and reliable therapy. Traditional pacing utilizes transvenous leads, which dwell in the venous system and place patients at risk for complications, including pneumothorax, bleeding, infection, vascular obstruction, and valvular compromise. Leadless pacemakers have been developed to overcome many of the challenges of transvenous pacing while providing safe and effective pacing therapy for an increasing population of patients. The Medtronic Micra transcatheter pacing system was approved by the FDA in April of 2016 and the Abbott Aveir pacemaker was approved in April of 2022. Several additional leadless pacemakers are in various stages of development and testing. There exists limited guidance on the selection of the ideal candidate for leadless pacemakers. Advantages of leadless pacemakers include decreased infection risk, overcoming limited vascular access, and avoidance of interaction with the tricuspid valve apparatus. Disadvantages of leadless pacemakers include right ventricular-only pacing, unclear lifecycle management, cost, perforation risk, and lack of integration with defibrillator systems. This review aims to provide an overview of the current state of the art of leadless pacemakers, currently approved systems, clinical trials and real-world evidence, considerations for patient selection, and future directions of this promising technology., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial., Methods and Results: The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047)., Conclusion: This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice., Competing Interests: Conflict of interest: R.E.K reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac and has stock options from AtaCor Medical Inc. S.M. reports consultancy fees from Boston Scientific. K.V. reports consultancy fees from Medtronic and Abbott. M.C.B. is a consultant and receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. D.J.W. has consultancy arrangements with Boston Scientific and Medtronic and a research grant from Boston Scientific. P.N. reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. M.A.M. reports consultancy fees from Boston Scientific. Z.I.W. is an advisor for Boston Scientific and on the advisory board for Medtronic and Abbot and reports speaker fees from Medtronic. The other authors report no conflicts., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.)

Background: Early subcutaneous implantable cardioverter-defibrillator (S-ICD) studies included atypical cohorts of patients who were younger with fewer comorbidities. Recent S-ICD studies included patient populations with more comorbidities., Objectives: The goals of this study were to determine the incidence and predictors of S-ICD-related infection over a 3-year follow-up period and to use these results to develop an infection risk score., Methods: The S-ICD Post Approval Study is a US prospective registry of 1637 patients. Baseline demographic characteristics and outcomes with 3-year postimplantation follow-up were compared between patients with and without device-related infection. A risk score was derived from multivariable proportional hazards analysis of 22 variables., Results: Infection was observed in 55 patients (3.3%), with 69% of infections occurring within 90 days and a vast majority (92.7%) within 1 year of implantation. Late infections more likely involved device erosion; no infections occurred after year 2. The annual mortality rate postinfection was 0.6%/y. No lead extraction complications or bacteremia related to infection were observed. An infection risk score was created with diabetes, age, prior transvenous ICD implant, and ejection fraction as predictors. Patients with a risk score of ≥3 had an 8.8 hazard ratio (95% confidence interval 2.8-16.3) of infection compared with a 0 risk score., Conclusion: Infection rates in the S-ICD Post Approval Study were similar to other S-ICD populations and not associated with systemic blood-borne infections. Late infection (>1 year) is uncommon and associated with system erosion. A high-risk infection cohort can be identified that may facilitate preventive measures., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)