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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.)

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.)

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.)

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.)

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.)

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.)

Purpose of Review: Leadless pacemakers (LPs) are emerging as alternative cardiac implantable devices for the treatment of bradyarrhythmia. This article aims to review the data behind the safety and efficacy of these devices while highlighting their pros and cons., Recent Findings: Prospective non-randomized studies and registries have found that LPs are associated with lower rate of device-related complications mainly driven by lower need for lead-related interventions as compared to traditional pacemakers. On the other hand, cardiac perforation appears to occur more frequently with LPs. LPs are associated with lower rate of device-related complications as compared to the traditional pacemakers. However, the rate of pericardial effusion is higher and is more severe. As we transition to multi-chamber LPs, it is important to ensure the safety and efficacy of these devices., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Aims: There is limited information on what clinical factors are associated with the development of pericardial effusion after leadless pacemaker implantation. We sought to determine predictors of and to develop a risk score for pericardial effusion in patients undergoing Micra leadless pacemaker implantation attempt., Methods and Results: Patients (n = 2817) undergoing implant attempt from the Micra global trials were analysed. Characteristics were compared between patients with and without pericardial effusion (including cardiac perforation and tamponade). A risk score for pericardial effusion was developed from 18 pre-procedural clinical variables using lasso logistic regression. Internal validation and future prediction performance were estimated using bootstrap resampling. The scoring system was also externally validated using data from the Micra Acute Performance European and Middle East (MAP EMEA) registry. There were 32 patients with a pericardial effusion [1.1%, 95% confidence interval (CI): 0.8-1.6%]. Following lasso logistic regression, 11 of 18 variables remained in the model from which point values were assigned. The C-index was 0.79 (95% CI: 0.71-0.88). Patient risk score profile ranged from -4 (lowest risk) to 5 (highest risk) with 71.8% patients considered low risk (risk score ≤0), 16.6% considered medium risk (risk score = 1), and 11.7% considered high risk (risk score ≥2) for effusion. The median C-index following bootstrap validation was 0.73 (interquartile range: 0.70-0.75). The C-index based on 9 pericardial effusions from the 928 patients in the MAP EMEA registry was 0.68 (95% CI: 0.52-0.83). The pericardial effusion rate increased significantly with additional Micra deployments in medium-risk (P = 0.034) and high-risk (P < 0.001) patients., Conclusion: The overall rate of pericardial effusion following Micra implantation attempt is 1.1% and has decreased over time. The risk of pericardial effusion after Micra implant attempt can be predicted using pre-procedural clinical characteristics with reasonable discrimination., Clinical Trial Registration: The Micra Post-Approval Registry (ClinicalTrials.gov identifier: NCT02536118), Micra Continued Access Study (ClinicalTrials.gov identifier: NCT02488681), and Micra Transcatheter Pacing Study (ClinicalTrials.gov identifier: NCT02004873)., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Clinical trials have demonstrated the safety and efficacy of the Micra leadless VVI pacemaker; however, longer-term outcomes in a large, real-world population with a contemporaneous comparison to transvenous VVI pacemakers have not been examined. We compared reinterventions, chronic complications, and all-cause mortality at 2 years between leadless VVI and transvenous VVI implanted patients., Methods and Results: The Micra Coverage with Evidence Development study is a continuously enrolling, observational, cohort study of leadless VVI pacemakers in the US Medicare fee-for-service population. Patients implanted with a leadless VVI pacemaker between March 9, 2017, and December 31, 2018, were identified using Medicare claims data linked to manufacturer device registration data (n = 6219). All transvenous VVI patients from facilities with leadless VVI implants during the study period were obtained directly from Medicare claims (n = 10 212). Cox models were used to compare 2-year outcomes between groups. Compared to transvenous VVI, patients with leadless VVI had more end-stage renal disease (12.0% vs. 2.3%) and a higher Charlson comorbidity index (5.1 vs. 4.6). Leadless VVI patients had significantly fewer reinterventions [adjusted hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.45-0.85, P = 0.003] and chronic complications (adjusted HR 0.69, 95% CI 0.60-0.81, P < 0.0001) compared with transvenous VVI patients. Adjusted all-cause mortality at 2 years was not different between the two groups (adjusted HR 0.97, 95% CI 0.91-1.04, P = 0.37)., Conclusion: In a real-world study of US Medicare patients, the Micra leadless VVI pacemaker was associated with a 38% lower adjusted rate of reinterventions and a 31% lower adjusted rate of chronic complications compared with transvenous VVI pacing. There was no difference in adjusted all-cause mortality at 2 years., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Early results from the Micra investigational trial and Micra Post-Approval Registry (PAR) demonstrated excellent safety and device performance; however, outcomes based on anticoagulation (AC) status at implant have not been evaluated., Objective: The purpose of this study was to report implant characteristics, perforation rate, and vascular-related events based on perioperative oral AC strategy in patients undergoing Micra implant., Methods: We compared procedure characteristics, major complications, and vascular events, including pericardial effusion, stratified by any adverse event (including major complications, minor complications, and observations) or major complication only according to AC status in the Micra PAR., Results: Among 1795 patients with AC status available, 585 were not on AC, 795 had AC interrupted, and 415 had AC continued during Micra implant. Non-AC patients tended to be younger, with less history of atrial fibrillation and chronic obstructive pulmonary disease, and more history of dialysis than interrupted and continued patients. The implant success rate was similar for all groups (99.1%-99.8%). Through 30 days postimplant, the overall major complication rate was 3.1% for the non-AC group, 2.6% for the interrupted group, and 1.5% for the continued group. The combined rate for any vascular or pericardial effusion adverse event did not differ significantly among AC strategies (6.5%, 4.8%, and 3.6%, respectively)., Conclusion: Implant of Micra seems to be safe and feasible regardless of an interrupted or continued periprocedural oral AC strategy, with no increased risk of perforation or vascular complications., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Leadless pacemakers (LPs) have revolutionized the field of pacing by miniaturizing pacemakers and rendering them completelty intracardiac, hence reducing complications related to pacemaker pockets and transvenous leads. However, first generation LPs appear to be associated with a higher rate of myocardial perforation as compared to transvenous pacemakers (TV-PPM). Currently, LPs are predominantly designed to pace the right ventricle with no LPs that provide atrial or biventricular pacing. In this article, we review the available data on LPs while advocating for the need for a randomized controlled trial comparing LPs to TV-PPMs. In addition, we review the future directions of leadless devices., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objectives: This study sought to formulate a predictive model for describing the long-term electrical performance of Micra (Medtronic, Mounds View, Minnesota)., Background: The Micra leadless pacemaker is an alternative ventricular pacing option that avoids the pitfalls of transvenous leads. However, well-defined metrics to predict the long-term electrical performance of the device are lacking., Methods: We identified all patients who underwent successful Micra implantation enrolled in the investigational device exemption study, continued access study, or post-approval registry with complete 1-year post-implantation data or system revision due to elevated thresholds (N = 1,843). The analysis endpoint was an elevated pacing capture threshold (PCT) at ≥12 months post-implantation, defined as ≥2.0 V at 0.24 ms or an increase of ≥1.5 V from implantation or need for system revision due to elevated thresholds at ≤12 months post-implantation. We evaluated for univariate and multivariate associations between patient and device characteristics at implantation and for elevated thresholds at 12 months., Results: Among the total cohort, 75 patients (4.1%) had elevated thresholds at 12 months; of these, 13 required system revisions. Predictors associated with elevated thresholds in univariate analysis included the total number of deployments (excluded from the multivariable model), impedance and PCT at implantation, male sex, history of diabetes, and ischemic cardiomyopathy. Multivariable regression modeling found that male sex, history of diabetes, implantation PCT of ≥2 V, and impedance of <800 Ω were independent predictors of elevated PCT at 12 months (all p < 0.05)., Conclusion: A history of diabetes, male sex, elevated PCT, and low impedance at implantation were independent predictors of elevated thresholds at 12 months. These metrics represent the foundation of a simple tool to aid in procedural decision making., Competing Interests: Funding Support and Author Disclosures Ms. Wallace is an employee and shareholder of Medtronic. Mr. Stromberg is an employee and shareholder of Medtronic. Dr. Piccini is supported by R01HL128595 from the National Heart, Lung, and Blood Institute; receives grants for clinical research from Abbott, the American Heart Association, Association for the Advancement of Medical Instrumentation, Bayer, Boston Scientific, and Philips; and serves as a consultant to Abbott, Allergan, ARCA Biopharma, Biotronik, Boston Scientific, LivaNova, Medtronic, Milestone, Myokardia, Sanofi, Philips, and UpToDate. Dr. Roberts has received honoraria from Medtronic. Dr. El-Chami has served as a consultant for Medtronic and Boston Scientific. Dr. Soejima has received honoraria for lecturing with Medtronic, Japan and Abbott, Japan. Dr. Garweg has received research funding from Biotronik, Boston Scientific, and Medtronic; and has received speaker fees and consultancy fees from Medtronic; Boston Scientific, and Biotronik. Dr. Fagan is an employee and shareholder of Medtronic. Dr. Lloyd has provided consulting and research support to Medtronic; and has provided research support to Boston Scientific. Dr. Kiani has reported that he has no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The feasibility and outcomes of concomitant atrioventricular node ablation (AVNA) and leadless pacemaker implant are not well studied. We report outcomes in patients undergoing Micra implant with concomitant AVNA., Methods: Patients undergoing AVNA at the time of Micra implant from the Micra Transcatheter Pacing (IDE) Study, Continued Access (CA) study, and Post-Approval Registry (PAR) were included in the analysis and compared to Micra patients without AVNA. Baseline characteristics, acute and follow-up outcomes, and electrical performance were compared between patients with and without AVNA during the follow-up period., Results: A total of 192 patients (mean age 77.4 ± 8.9 years, 72% female) underwent AVNA at the time of Micra implant and were followed for 20.4 ± 15.6 months. AVNA patients were older, more frequently female, and tended to have more co-morbid conditions compared with non-AVNA patients (N = 2616). Implant was successful in 191 of 192 patients (99.5%). The mean pacing threshold at implant was 0.58 ± 0.35 V and remained stable during follow-up. Major complications within 30 days occurred more frequently in AVNA patients than non-AVNA patients (7.3% vs. 2.0%, p < .001). The risk of major complications through 36-months was higher in AVNA patients (hazard ratio: 3.81, 95% confidence interval: 2.33-6.23, p < .001). Intermittent loss of capture occurred in three AVNA patients (1.6%), all were within 30 days of implant and required system revision. There were no device macrodislodgements or unexpected device malfunctions., Conclusion: Concomitant AVN ablation and leadless pacemaker implant is feasible. Pacing thresholds are stable over time. However, patient comorbidities and the risk of major complications are higher in patients undergoing AVNA., (© 2021 The Authors. Journal of Cardiovascular Electrophysiology Published by Wiley Periodicals LLC.)

Background: Data on the management of Micra transcatheter pacing system (TPS) at the time of an upgrade or during battery depletion is limited., Objective: We sought to evaluate the management patterns of patients implanted with a Micra TPS during long-term follow-up., Methods: We retrospectively identified patients who underwent Micra implantation from April 2014 to November 2019. We identified patients who underwent extraction (n = 11) or had an abandoned Micra (n = 12)., Results: We identified 302 patients who received a Micra during the period of the study. Mean age was 72.7 ± 15.4 years, 54.6% were men, and left ventricular ejection fraction was 51.9 ± 5.2%. Mean follow-up was 1105.5 ± 529.3 days. Procedural complications included pericardial tamponade (n = 1) treated with pericardiocentesis, significant rise in thresholds (n = 6) treated with reimplantation (n = 4), and major groin complications (n = 2). Indications for extraction included an upgrade to cardiac resynchronization therapy (CRT) device (n = 3), bridging after extraction of an infected transvenous system (n = 3), elevated thresholds (n = 3), and non-Micra-related bacteremia (n = 2). The median time from implantation to extraction was 78 days (interquartile range: 14-113 days), with the longest extraction occurring at 1442 days. All extractions were successful, with no procedural or long-term complications. Indications for abandonment included the need for CRT (n = 6), battery depletion (n = 2), increasing thresholds/failure to capture (n = 3), and pacemaker syndrome (n = 1). All procedures were successful, with no procedural or long-term complications., Conclusion: In this large single-center study, 6% of patients implanted with a Micra required a system modification during long-term follow-up, most commonly due to the requirement for CRT pacing. These patients were managed successfully with extraction or abandonment., (© 2020 Wiley Periodicals LLC.)

Micra leadless pacemaker has progressed from a single chamber pacemaker that can deliver VVIR pacing to a pacing device that can provide atrio-ventricular (AV) synchrony via a unique pacing algorithm that relies on identifying mechanical atrial contraction. This novel algorithm has its own limitations and intricacies. In this paper, we review this algorithm, suggest steps for troubleshooting and programming these devices and provide clinical examples of Micra AV cases that required changes in programming for adequate tracking of atrial activity., (© 2020 The Authors. Journal of Cardiovascular Electrophysiology Published by Wiley Periodicals LLC.)

Background: The Micra transcatheter pacemaker is a safe and effective alternative to transvenous permanent pacemakers (TV-PPMs). However, the safety profile and mortality outcomes of Micra implantation in patients deemed poor candidates for TV-PPM are incompletely understood., Objective: The purpose of this study was to evaluate safety and all-cause mortality in patients undergoing Micra implantation stratified by whether they were precluded for therapy with a TV-PPM., Methods: Patients from the Micra clinical trials were divided into groups on the basis of whether the implanter considered the patient to be precluded from receiving a TV-PPM. Micra groups were compared with one another as well as with a historical cohort of patients who received a single-chamber TV-PPM., Results: A total of 2817 patients underwent a Micra implantation attempt, of whom 546 (19%) patients deemed ineligible for TV-PPM implantation for reasons such as venous access issues or prior device infections. Both acute mortality (2.75% vs 1.32%; P=.022) and total mortality at 36 months (38.1% vs 20.6%; P<.001) were significantly higher in the precluded group than in the nonprecluded group. Mortality was similar among nonprecluded patients and patients implanted with a TV-PPM. The major complication rate through 36 months was similar between the 2 Micra groups (3.81% vs 4.30%; P=.40)., Conclusion: All-cause mortality is higher in Micra patients deemed ineligible for TV-PPM implantation than in nonprecluded Micra patients and those who received a TV-PPM, in part related to a higher incidence of chronic comorbidities in these patients. The overall major complication rate was low and did not differ by preclusion status., Clinical Trial Registration: Micra Post-Approval Registry ClinicalTrials.gov identifier: NCT02536118; Micra Continued Access Study ClinicalTrials.gov identifier: NCT02488681; Micra Transcatheter Pacing Study ClinicalTrials.gov identifier: NCT02004873; Medtronic Product Surveillance Registry ClinicalTrials.gov identifier: NCT01524276., (Copyright © 2020 Heart Rhythm Society. All rights reserved.)

Pacemaker-related infections remain a constant concern due to increased risk of patient morbidity and mortality. Although transvenous pacemakers are expected to have an infection rate ranging from 0.77% to 2.08%, no cases of leadless pacemaker infection have been reported in clinical trials enrolling more than 3000 patients. Many potential reasons why leadless pacemakers may be resistant to infection include the absence of a subcutaneous pocket and leads, reduced skin and glove contact, size, location, and device material. This review summarizes the current state of evidence regarding the apparent infection resistance of leadless pacemakers., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Infections of cardiac implantable electronic devices remain a prevalent health concern necessitating the advent of novel preventative strategies. Based on the observation that bacterial infections of the Micra transcatheter pacemaker device are extremely rare, we examine the effect of parylene coating on bacterial adhesion and growth., Methods: Bacterial growth was compared on polyurethane coated, bare, or parylene coated titanium surfaces. Eight test samples per bacterial species and material combination were incubated with Staphylococcus Aureus or Pseudomonas aeruginosa for 24 hours and then assayed for bacterial growth. The surface contact angle was also characterized by measuring the angle between the tangent to the surface of a liquid droplet made with the surface of the solid sample., Results: The mean bacterial colony counts were significantly reduced for both parylene coated titanium versus bare samples (3.69 ± 0.27 and 4.80 ± 0.48 log[CFU/mL] respectively for S. aureus [P < .001] and 5.51 ± 0.27 and 6.08 ± 0.11 log[CFU/mL] respectively for P. aeruginosa [P < .001]), and for parylene coated titanium versus polyurethane samples (4.27 ± 0.42 and 5.40 ± 0.49 log[CFU/mL] respectively for S. aureus [P < .001] and 4.23 ± 0.42 and 4.84 ± 0.32 log[CFU/mL] respectively for P. aeruginosa [P = .006]). Parylene coated titanium samples had a higher contact angle compared with bare titanium, but lower compared with polyurethane (mean contact angle 87.5 ± 3.1 degrees parylene, 73.3 ± 3.7 degrees titanium [P < .001 vs parylene], and 94.8 ± 3.7 degrees polyurethane [P = .002 vs parylene])., Conclusions: Parylene coating significantly reduced the ability of bacteria to grow in colony count assays suggesting that this could contribute to the reduction of bacterial infections of Micra transcatheter pacemakers., (© 2020 Wiley Periodicals, Inc.)

Aims: Patient selection is a key component of securing optimal patient outcomes with leadless pacing. We sought to describe and compare patient characteristics and outcomes of Micra patients with and without a primary pacing indication associated with atrial fibrillation (AF) in the Micra IDE trial., Methods and Results: The primary outcome (risk of cardiac failure, pacemaker syndrome, or syncope related to the Micra system or procedure) was compared between successfully implanted patients from the Micra IDE trial with a primary pacing indication associated with AF or history of AF (AF group) and those without (non-AF group). Among 720 patients successfully implanted with Micra, 228 (31.7%) were in the non-AF group. Reasons for selecting VVI pacing in non-AF patients included an expectation for infrequent pacing (66.2%) and advanced age (27.2%). More patients in the non-AF group had a condition that precluded the use of a transvenous pacemaker (9.6% vs. 4.7%, P = 0.013). Atrial fibrillation patients programmed to VVI received significantly more ventricular pacing compared to non-AF patients (median 67.8% vs. 12.6%; P < 0.001). The overall occurrence of the composite outcome at 24 months was 1.8% with no difference between the AF and non-AF groups (hazard ratio 1.36, 95% confidence interval 0.45-4.2; P = 0.59)., Conclusion: Nearly one-third of patients selected to receive Micra VVI therapy were for indications not associated with AF. Non-AF VVI patients required less frequent pacing compared to patients with AF. Risks associated with VVI therapy were low and did not differ in those with and without AF., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Extraction of transvenous leads via the femoral route might be needed when extraction via the implant vein fails or when retained lead fragments exist. The skill set required for this procedure is unique as it relies on the ability to snare and the use of a variety of shelf tools. In this era of leadless pacing, this skill set might be called upon more frequently. In this article, we review the data, tools, and procedural steps of femoral lead extraction and retrieval/extraction of leadless pacemakers., (© 2019 Wiley Periodicals, Inc.)

Background: The Micra clinical trials have enrolled more than 2500 patients without any reported device-related infections that required removal during follow-up. Leadless pacemakers might be more resistant to bacterial seeding due to smaller surface area and a greater tendency for encapsulation., Objective: To analyze the incidence and outcomes of serious infectious events (SIEs: bacteremia or endocarditis) that developed during follow-up in patients with history of Micra leadless pacemaker implantation., Methods: SIE and outcomes were characterized based upon adverse event reports. Among 720 patients implanted with Micra in the investigational device exemption trial, we identified 16 patients who had documented 21 SIEs during follow-up., Results: Among patients with SIEs, mean age was 71.9 ± 11.7 years. SIEs occurred at a mean 4.8 ± 4.5 months after implant and patients were followed for 13.1 ± 9.1 months after documentation of SIE. All events were adjudicated as unrelated to the Micra device or procedure. Bacteremia was documented to be related to a gram-positive organism in 13 events (seven Staphylococcus, three Streptococcus, two Enterococcus, and one uncharacterized gram-positive bacteria), and gram-negative organisms in three events. In five events, the type of organism was not characterized (two patients with endocarditis). No persistent cases of bacteremia after antibiotic cessation were seen over the duration of follow-up CONCLUSION: In this small series of Micra patients who developed SIEs postimplant, the occurrence of bacteremia and/or endocarditis did not appear to lead to persistent bacteremia off antibiotics; most events resolved with antibiotic treatment., (© 2019 Wiley Periodicals, Inc.)

Background: Implantation of the MICRA Leadless pacemaker requires the use of a 27 French introducer, blunt delivery system and device fixation to the myocardium via nitinol tines. While prior studies have proven its safety, it is unclear whether performing this procedure with uninterrupted anticoagulation exposes patients to increased risks. We sought to investigate the feasibility and safety of continuing therapeutic anticoagulation during the periprocedural period., Methods: We evaluated all patients undergoing MICRA placement at our institution between April 2014 and August 2018 with complete follow-up data (n = 170). Patients were stratified into two groups: those on active anticoagulation (OAC, n = 26), defined as having an International normalized ratio >2.0 or having continued a direct oral anticoagulant, and those not anticoagulated (Off-OAC, n = 144). We evaluated for a composite outcome of all major complications, including access site complications and pericardial effusion., Results: OAC and Off-OAC groups had similar mean age (74 ± 13 vs 75 ± 13 years; P = .914). The OAC group had a nonsignificantly lower prevalence of end-stage renal disease (8% vs 17%; P = .375) and aspirin use (27% vs 47%; P = .131). Those in the OAC group were more likely to be on warfarin than those in the Off-OAC group (81% vs 30%; P < .001). The rate of the composite endpoint was similar between the OAC and Off-OAC groups (3.8 % vs 1.4%, respectively; P = .761). Length of stay was similar between groups (1.3 ± 2.6 vs 2.3 ± 3.4 days; P = 0.108)., Conclusion: Continuation of therapeutic anticoagulation during MICRA implantation appears to be feasible, safe and associated with shorter hospitalization among appropriately selected individuals., (© 2019 Wiley Periodicals, Inc.)

Introduction: Leadless pacemakers may provide a safe and attractive pacing option to patients with cardiac implantable electronic device (CIED) infection. We describe the characteristics and outcomes of patients with a recent CIED infection undergoing Micra implant attempt., Methods and Results: Patients with prior CIED infection and device explant with Micra implant within 30 days, were identified from the Micra post approval registry. Procedure characteristics and outcomes were summarized. A total of 105 patients with prior CIED infection underwent Micra implant attempt ≤30 days from prior system explant (84 [80%] pacemakers and 13 [12%] ICD/CRT-D). All system components were explanted in 93% of patients and explant occurred a median of 6 days before Micra implant, with 37% occurring on the day of Micra implant. Micra was successfully implanted in 99% patients, mean follow-up duration was 8.5 ± 7.1 months (range 0-28.5). The majority of patients (91%) received IV antibiotics preimplant, while 42% of patients received IV antibiotics postprocedure. The median length of hospitalization following Micra implant was 2 days (IQR, 1-7). During follow-up, two patients died from sepsis and four patients required system upgrade, of which two patients received Micra to provide temporary pacing support. There were no Micra devices explanted due to infection., Conclusion: Implantation of the Micra transcatheter pacemaker is safe and feasible in patients with a recent CIED infection. No recurrent infections that required Micra device removal were seen. Leadless pacemakers appear to be a safe pacing alternative for patients with CIED infection who undergo extraction., (© 2019 The Authors. Journal of Cardiovascular Electrophysiology Published by Wiley Periodicals, Inc.)

Background: The performance of Abbott/St. Jude Medical (Sylmar CA) Tendril pacing leads has not been well characterized., Objective: We sought to assess the performance of Tendril leads as compared with that of different pacing leads., Methods: We retrospectively identified patients implanted with the following leads: Tendril leads 1888 TC, 2088 TC, and 1688 TC, Medtronic (Fridely, MN) 4076 CapSureFix Novus, and Boston Scientific (Natick, MA) FINELINE II Sterox Pacing EZ leads (models 4469, 4470, and 4471). The primary end point was the incidence of lead malfunction assessed by Kaplan-Meier analysis., Results: During the study period, 9782 leads were implanted, including 8512 Tendril leads, 731 Medtronic 4076 CapSureFix Novus leads, and 539 FINELINE II leads. A total of 540 leads (5.5%) malfunctioned during a mean follow-up of 3.6 ± 2.9 years. Lead malfunction manifested predominantly as noise and/or low impedance (95%). Lead malfunction rates were significantly higher at 5 years for Tendril vs non-Tendril leads (7.0% vs 2.1%; P < .001). The highest rate of failure at 5 years was seen in the Tendril 1888 TC leads (9.9%), followed by Tendril 1688 (5.7%) and Tendril 2088 (5.2%) leads. In contrast, malfunction rates were significantly lower for the Medtronic 4076 (2.6%) and FINELINE II (1.7%) leads. During follow-up to 10 years, the incidence of lead malfunction for Optim-insulated Tendril leads (models 1888 TC and 2088 TC) was significantly higher than that for the non-Optim-insulated Tendril 1688 TC lead (24.5% vs 7.1%) (P = .008)., Conclusion: Tendril leads appear to have a higher rate of malfunction than do comparator leads. Optim insulation may partly explain the higher failure rate., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to report periprocedural outcomes and intermediate-term follow-up of hemodialysis patients undergoing Micra implantation., Background: Leadless pacemakers may be preferred in patients with limited vascular access and high-infection risk, such as patients on hemodialysis., Methods: Patients on hemodialysis at the time of Micra implantation attempt (n = 201 of 2,819; 7%) from the Micra Transcatheter Pacing Study investigational device exemption trial, Micra Transcatheter Pacing System Continued Access Study Protocol, and Micra Transcatheter Pacing System Post-Approval Registry were included in the analysis. Baseline characteristics, periprocedural outcomes, and intermediate-term follow-up were summarized., Results: Patients on hemodialysis at the time of Micra implantation attempt were on average 70.5 ± 13.5 years of age and 59.2% were male. The dialysis patients commonly had hypertension (80%), diabetes (61%), coronary artery disease (39%), and congestive heart failure (27%), and 72% had a condition that the implanting physician felt precluded the use of a transvenous pacemaker. Micra was successfully implanted in 197 patients (98.0%). Reasons for unsuccessful implantation included inadequate thresholds (n = 2) and pericardial effusion (n = 2). The median implantation time was 27 min (interquartile range: 20 to 39 min). There were 3 procedure-related deaths: 1 due to metabolic acidosis following a prolonged procedure duration in a patient undergoing concomitant atrioventricular nodal ablation and 2 deaths occurred in patients who needed surgical repair after perforation. Average follow-up was 6.2 months (range 0 to 26.7 months). No patients had a device-related infection or required device removal because of bacteremia., Conclusions: Leadless pacemakers represent an effective pacing option in this challenging patient population on chronic hemodialysis. The risk of infection appears low with an acceptable safety profile. (Micra Transcatheter Pacing Study; NCT02004873; Micra Transcatheter Pacing System Continued Access Study Protocol; NCT02488681; Micra Transcatheter Pacing System Post-Approval Registry; NCT02536118)., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Early results of the Micra Investigational Device Exemption (IDE) study and Micra Post-Approval Registry (PAR) demonstrated excellent safety and efficacy performance; however, intermediate-term results across a large patient population in the real-world setting have not been evaluated., Objectives: We report updated performance of the Micra transcatheter pacemaker from a worldwide PAR and compare it with the IDE study as well as a transvenous historical control., Methods: The safety objective of the analysis was system- or procedure-related major complications through 12 months postimplantation. We compared the major complication rate with that of the 726 patients from the IDE and with a reference data set of 2667 patients with transvenous pacemakers by using a Fine-Gray competing risk model., Results: The Micra device was successfully implanted in 1801 of 1817 patients (99.1%). The mean follow-up period was 6.8 ± 6.9 months. Through 12 months, the major complication rate was 2.7% (95% confidence interval [CI] 2.0%-3.7%). The risk of major complications for Micra PAR patients was 63% lower than that for patients with transvenous pacemakers through 12 months postimplantation (hazard ratio 0.37; 95% CI 0.27-0.52; P < .001). The major complication rate trended lower in the PAR than in the IDE study (hazard ratio 0.71; 95% CI 0.44-1.1; P = .160), driven by the lower pericardial effusion rate in the PAR. There were 3 cases of infection associated with the procedure, but none required device removal and there were no battery or telemetry issues. Pacing thresholds were low and stable through 12 months postimplantation., Conclusion: Performance of the Micra transcatheter pacemaker in international clinical practice remains consistent with previously reported data. Major complications were infrequent and occurred 63% less often compared to transvenous systems., Clinical Trial Registration: Micra Transcatheter Pacing System Post-Approval Registry ClinicalTrials.gov identifier: NCT02536118; Micra Transcatheter Pacing Study ClinicalTrials.gov identifier: NCT02004873., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Recommendations regarding performance of magnetic resonance imaging (MRI) in non-MRI conditional pacemaker and defibrillator recipients are evolving. Previous studies have suggested low adverse event rates with MRI in nonconditional cardiac implantable electronic device (CIED) recipients, but low power limits optimal characterization of risk., Objective: The purpose of this study was to perform a systematic review and meta-analysis to characterize the clinical risk associated with MRI in CIED recipients in order to improve power., Methods: PubMed and CINAHL indexed articles from 1990 to 2017 were queried. A random effects model was used for meta-analysis of continuous variables. Safety outcomes were evaluated with descriptive statistics., Results: Seventy studies of non-MRI conditional devices undergoing MRI were identified, allowing for analysis of 5099 patients who underwent a total of 5908 MRI studies. Heterogeneity in lead parameter changes was observed within studies, although smaller variances were noted between studies. All lead characteristics and battery voltages showed very small, clinically insignificant changes when assessed as a pooled cohort, although cases of clinically relevant outcomes were also noted (lead failure 3, implantable cardioverter-defibrillator shock 1, electrical reset 94). Electrical resets were found only in older devices. Defibrillator function was unchanged, and inappropriate shocks were avoided with pre-MRI programming changes., Conclusion: This review demonstrated low lead failure and clinical event rates in non-MRI conditional pacemaker and defibrillator recipients undergoing MRI. Observed changes were small and interstudy variance was low, suggesting that the composite event rates offer a reasonable estimate of true effect. The observed adverse events reinforce the need for ongoing vigilance and caution, particularly with older devices., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The decision to abandon or extract superfluous sterile leads is controversial., Objective: The purpose of this study was to compare procedural outcomes and long-term survival of patients with and those without abandoned leads undergoing lead extraction (LE)., Methods: Retrospective review of all patients who had undergone transvenous LE at our institution from January 2007 to May 2016 was performed. Patients were stratified into 2 groups based on the presence (group 1) or absence (group 2) of abandoned leads., Results: Among 774 patients who had undergone LE procedures, 38 (4.9%) had abandoned leads (group 1). Dwell time of the oldest extracted lead was longer in group 1 vs group 2 (7.6 ± 4.9 years vs 5.6 ± 4.4 years; P = .017), as was infection as an indication for LE (76% vs 33%; P <.001). A bailout femoral approach was more commonly required in group 1 than in group 2 (18.4% vs 6%; P = .007). Complete procedural success rates were similar (92.1% in group 1 vs 95.0% in group 2; P = .439), but there was a trend toward lower clinical success in group 1 (92.1% vs 97.4%; P = .088), primarily due to failure to remove all hardware in the setting of infection. Major procedural complication rates were similar (2.6% in group 1 vs 1.2% in group 2; P = .397), as was long-term survival (mean follow-up 2.3 ± 2.2 years)., Conclusion: Abandoned leads at the time of LE were associated with increased procedural complexity, including a higher rate of bailout femoral extraction, and may be associated with lower clinical success. Among appropriately selected patients, consideration should be given to LE instead of abandonment., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrioventricular junctional (AVJ) ablation and pacemaker implantation are indicated when pharmacotherapy fails to achieve adequate rate control in atrial fibrillation (AF). The purpose of our study is to assess the feasibility and safety of concurrent Micra leadless transcatheter pacemaker implantation and AVJ ablation., Methods: We retrospectively assessed patients who underwent Micra implantation and concurrent AVJ ablation at three institutions between August 2014 and March 2016. All patients and devices were followed at baseline and at 1, 3, 6, and 12 months postimplantion., Results: Twenty-one patients with permanent AF (median age 77 [range: 62-88], female 15 [71.4%]) underwent successful Micra implantation followed by concurrent AVJ ablation. There was no device dislodgement or malfunction during the 12-month follow-up. Complete 12-month electrical performance data were available in 14 patients (67%). Among patients with the complete data set, median pacing thresholds at implant and at 1, 3, 6, and 12 months were 0.5 V (range: 0.25-0.88), 0.44 V (range: 0.25-2.0), 0.5 V (range: 0.25-1.63), 0.5 V (range: 0.25-1.13), and 0.5 V (range: 0.25-1.13) at a pulse width of 0.24 msec, respectively. Two patients died due to noncardiac causes during follow-up. There were no patients with major device-related complications., Conclusions: Concurrent Micra implantation and AVJ ablation is feasible and appears safe. There was no device dislodgement, malfunction, or significant pacing threshold rise requiring device reimplantation during the 12-month follow-up. This combined approach can be considered for patients with AF with suboptimal rate control who have failed AF catheter ablation and/or pharmacotherapy., (© 2018 Wiley Periodicals, Inc.)

Background: First-in-man studies of leadless pacemakers have demonstrated high rates of implant success, and safety and efficacy objectives were achieved. Outside of the investigational setting, there are concerns, particularly over cardiac effusion and perforation, device dislodgement, infection, telemetry, and battery issues., Objective: The acute performance of the Micra transcatheter pacemaker from a worldwide Post-Approval Registry is reported., Methods: The registry is an ongoing prospective single-arm observational study designed to assess the safety and effectiveness of Micra in the post-approval setting. The safety end point was system- or procedure-related major complications at 30 days post implant. We compared the major complication rate with that of the 726 patients from the investigational study. Electrical performance was also characterized., Results: The device was successfully implanted in 792 of 795 registry patients (99.6%) by 149 implanters at 96 centers in 20 countries. Through 30 days post implant, a total of 13 major complications occurred in 12 patients, for a major complication rate of 1.51% (95% confidence interval, 0.78%-2.62%). Major complications included cardiac effusion/perforation (1, 0.13%), device dislodgement (1, 0.13%), and sepsis (1, 0.13%). After adjusting for baseline differences, the rate of major complications in the registry trended lower than the investigational trial (odds ratio, 0.58, 95% confidence interval, 0.27-1.25; P = .16). Early pacing capture thresholds were low and stable., Conclusion: Performance of the Micra transcatheter pacemaker in a real-world setting demonstrates a high rate (99.6%) of implant success and low rate (1.51%) of major complications through 30 days post implant. In particular, the rates of pericardial effusion, device dislodgement, and infection were low, reinforcing the positive results seen in the investigational study., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Octogenarians account for a significant percentage of patients with indwelling pacemakers or defibrillators., Objectives: To determine procedural outcomes and long-term survival after lead extraction (LE) in octogenarians., Methods: We retrospectively identified all patients who underwent defibrillator or pacemaker LE at our institution between January 1, 2007 and May 31, 2016. Patients were stratified based on age into two groups: <80 years old (Group 1, n = 674) or ≥80 (Group 2, n = 100). Outcomes were determined by medical records review and query of the Social Security Death Index., Results: Patients in Group 2 were more likely to be hypertensive (77% vs 61%, P = 0.02), more like to have coronary artery disease (50% vs 39%, P = 0.049), and more likely to be extracted for infectious indications (47% vs 33%, P = .009). The number of leads extracted per procedure was 2.0 ± 0.8 and the mean dwell time of the oldest extracted lead was 5.6 ± 4.3 years, without significant differences between groups. Extraction procedure success (Group 1: 94.7%, Group 2: 96%, P = 0.808) and procedural deaths (Group 1: 0.9% vs Group 2: 0%, P = 1.0) were similar. There was no significant difference in survival up to 3 years following LE between groups., Conclusion: At experienced centers, LE can be performed safely in octogenarians with procedural success rates and long-term survival comparable to younger individuals., (© 2017 Wiley Periodicals, Inc.)

Objectives: This study compared risks associated with magnetic resonance imaging (MRI) in patients with non-MRI conditional and MRI conditional pacing and defibrillator systems with particular attention to clinically actionable outcomes., Background: While recipients of new MRI conditional pacemaker and defibrillator systems may undergo MRI scanning with very low risk, safety and regulatory concerns persist regarding such scanning in recipients of non-MRI conditional systems., Methods: Patients with any cardiac device who were referred for MRI were prospectively enrolled at a single center and underwent scanning at 1.5 Tesla. Pre- and postscan lead characteristic changes, system integrity, and symptoms were analyzed. A comparison was made between non-MRI conditional and MRI conditional devices., Results: 105 patients were evaluated allowing for comparison of 97 scans with non-MRI conditional devices and 16 scans with MRI conditional devices. The cohort included those with pacemaker dependency, defibrillator, and cardiac resynchronization devices. Small, nonsignificant changes were observed in lead characteristics following scanning, and there was no significant difference when comparing non-MRI and MRI conditional devices. Lead parameter changes did not require lead revision or programming changes. No device reset, failures, or premature scan termination was observed., Conclusions: 1.5 T MRI scanning in patients with MRI conditional and non-MRI conditional cardiac devices was performed with similar, low clinical risk., (© 2017 Wiley Periodicals, Inc.)

Background: Extraction of pacemaker and defibrillator leads in young adults may be technically challenging because of more extensive fibrosis and calcification in this patient population., Objective: The purpose of this study was to examine outcomes of lead extraction (LE) in young adults at our institution., Methods: We retrospectively identified all patients who underwent LE at our institution between January 1, 2007, and May 31, 2016. Patients were divided by age into 2 groups: <40 years (group 1, n = 84) or ≥40 years (group 2, n = 690). Outcomes were determined by medical records review., Results: Patients in group 2 had a higher overall average number of leads extracted per procedure compared to group 1 (1.64 ± 0.80 vs 1.45 ± 0.64; P <.001). Lead dwell time was similar in the 2 groups (5.7 ± 5 years vs 5.6 ± 4.3 years; P = .95). The younger cohort tended to require femoral extraction techniques more frequently (9.5% vs 4.4%; P = .055). Extraction procedural success (group 1: 94.1%, group 2: 94.9%; P = .792), major complications (group 1: 0%, group 2: 1.3%; P = 1), and periprocedural mortality (group 1: 0%, group 2: 0.86%; P = 1) were similar in the 2 groups., Conclusion: LE can be performed safely and effectively in young adults. Despite the lower number of leads extracted per procedure and the similar lead dwell time, younger adults more frequently required the use of femoral extraction tools, thus highlighting the importance of performing these procedures in centers with advanced expertise in extraction techniques., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Leadless pacing is an emerging technology with the potential to significantly improve outcomes associated with the need for long-term pacing. Specifically, the major advantage of leadless systems is abolishing the need for transvenous leads and subcutaneous pockets, both of which account for most adverse events associated with traditional pacemakers. Two leadless pacemakers are currently available: the Nanostim (leadless cardiac pacemaker [LCP]) device (St. Jude Medical, Sylmar, California) and the Micra Transcatheter pacing system (Medtronic, Minneapolis, Minnesota). These 2 pacemakers have shown promising results in clinical trials. In conclusion, in this review we summarize the results of the 2 investigational device exemption trials and compare the pros and cons of these devices to traditional transvenous pacemakers., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Two major studies have shown that leadless pacemakers are safe and effective for patients requiring right ventricular rate responsive pacing therapy. This positive result recently led to FDA approval of one of the available leadless pacing devices. While this new technology is promising, it requires a different skill set for safe implantation. In this article, we review in detail the different steps required for implantation of tine-based leadless pacemakers while providing tips and tricks to minimize complications., (© 2016 Wiley Periodicals, Inc.)

Objective: The purpose of this study was to evaluate the safety and diagnostic utility of 1.5-T MRI examinations of individuals with conventional and MRI-conditional cardiac implantable electronic devices (CIEDs)., Subjects and Methods: Patients with a CIED who were referred for MRI were evaluated by radiologists and cardiac electrophysiologists for study participation. CIED interrogation was performed immediately before and after MRI, and cardiac telemetry monitoring was performed during MRI. CIED programming changes, malfunctions, and intraprocedural events were documented. Whether diagnostic questions were answered and whether artifacts related to the CIED were present and negatively affected image interpretation were recorded., Results: One hundred thirteen MRI examinations were performed for 104 patients with CIEDs (74 pacemakers [60 conventional, 14 MRI conditional]; 39 implantable cardiac defibrillators). Device reprogramming was required before MRI for 62.8% of studies (71/113). No significant changes in lead parameters were noted during or after MRI. Electromagnetic noise was detected on at least one lead in 7.1% of studies. Three patients reported transient symptoms (one case each of heating at the pocket site, tingling at the pocket site, and palpitations). All images were considered diagnostic for the original clinical query. Artifacts related to CIEDs were described in 3.5% of MRI reports (4/113) and were present only when the pulse generator was included in the FOV. CIED-related artifacts limited evaluation of tissues immediately adjacent to the pulse generator., Conclusion: Establishment of a multidisciplinary work flow allows individuals with conventional and MRI-conditional CIEDs to safely undergo 1.5-T MRI with diagnostic questions consistently answered.

Objectives: The purpose of this study was to identify predictors and clinical implications of permanent pacemaker (PPM) implantation after transcatheter aortic valve replacement (TAVR)., Background: Cardiac conduction disturbances requiring PPM are a frequent complication of TAVR. However, limited data is available regarding this complication after TAVR with a balloon-expandable valve., Methods: The study included patients without prior pacemaker who underwent TAVR in the PARTNER (Placement of AoRtic TraNscathetER Valves) trial and registry and investigated predictors and clinical effect of new PPM., Results: Of 2,559 TAVR patients, 586 were excluded due to pre-existing PPM. A new PPM was required in 173 of the remaining 1,973 patients (8.8%). By multivariable analysis, predictors of PPM included right bundle branch block (odds ratio [OR]: 7.03, 95% confidence interval [CI]: 4.92 to 10.06, p < 0.001), prosthesis diameter/left ventricular (LV) outflow tract diameter (for each 0.1 increment, OR: 1.29, 95% CI: 1.10 to 1.51, p = 0.002), LV end-diastolic diameter (for each 1 cm, OR: 0.68, 95% CI: 0.53 to 0.87, p = 0.003), and treatment in continued access registry (OR: 1.77, 95% CI: 1.08 to 2.92, p = 0.025). Patients requiring PPM had a longer mean duration of post-procedure hospitalization (7.3 ± 2.7 days vs. 6.2 ± 2.8 days, p = 0.001). At 1 year, new PPM was associated with significantly higher repeat hospitalization (23.9% vs. 18.2%, p = 0.05) and mortality or repeat hospitalization (42.0% vs. 32.6%, p = 0.007). There was no difference between groups in LV ejection fraction at 1 year., Conclusions: PPM was required in 8.8% of patients without prior PPM who underwent TAVR with a balloon-expandable valve in the PARTNER trial and registry. In addition to pre-existing right bundle branch block, the prosthesis to LV outflow tract diameter ratio and the LV end-diastolic diameter were identified as novel predictors of PPM after TAVR. New PPM was associated with a longer duration of hospitalization and higher rates of repeat hospitalization and mortality or repeat hospitalization at 1 year. (THE PARTNER TRIAL: Placement of AoRtic TraNscathetER Valves Trial; NCT00530894)., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Modern implantable devices capable of pacing are armed with a multitude of programmable and automated features. While some features represent important advances in device safety and performance, many can also mimic device malfunction. This article discusses these features in terms of the confusion they may cause and highlights important clinical clues that aid in their recognition.