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Introduction:Electrograms (EGMs) generated by implantable cardiac devices at the time of non-cardiac death may have artifact from non-arrhythmic sources, such as coagulated blood and air bubbles. While few studies have described the nature of terminal EGMs in non-cardiac death, it is clinically and medicolegally important to characterize these EGMs to elucidate events that may otherwise be misinterpreted as device failure. Here we investigated terminal EGM features that may aid clinicians in discerning cardiac from non-cardiac death.Methods:Terminal EGMs were analyzed by independent physician reviewers. Deaths were adjudicated as non-cardiac based on direct clinical data at the time of death using a modified Cardiac Arrhythmia Suppression Trial approach. In total, 16 non-cardiac terminal EGMs were identified and compared to a control cohort of true arrhythmic events. Using a subset of identified EGMs, an 8-question survey was administered to electrophysiologists blinded to cause of death. Several variables were identified as important for the correct classification of EGMs. The statistical performance of each variable for detecting non-cardiac death and true arrhythmias in our sample was evaluated. These results were shared, and the survey was readministered.Results:In our sample, absence of organized atrial activity had a sensitivity (SN) of 78.5%, specificity (SP) of 100%, and positive predictive value (PPV) of 100% for non-cardiac terminal EGMs. Cycle length <130 ms and absence of discernible deflections both had SPs and PPVs of 100% for non-cardiac death but were less sensitive (60% and 20%, respectively). An abrupt change following therapy and response to therapy both had SNs, SPs, and PPVs of 100% for true arrhythmias. Survey response rate was 68.8% and 62.5% for the pre- and post-survey, respectively. Pre-survey scores ranged from 50 – 87.5% correct with a mean of 72.7%. Post-survey scores ranged from 75 – 100% with a mean of 86.3% (p< 0.01).Conclusions:There is variability and inaccuracy among expert physicians' interpretation of EGMs during non-cardiac death. The variables identified in this study will aid in the development of a clinical risk score used to discern non-cardiac death and true device malfunction based on terminal EGMs.

Introduction:The increasing prevalence of pacemaker lead noise indicating insulation breach has previously been described. Unfortunately, early detection is neither predictable nor accurate by traditional measurements. “Pseudo-unipolarization” of bipolar pacing stimuli as observed from routine 12-lead EKG due to current leak holds promise as a means of detecting insulation breaches. We sought to characterize this EKG finding to better detect lead malfunction.Methods:138 patients who received transvenous lead implantations with pacing noted on EKG at time of implant (control group, n=50) or after time of known malfunction (malfunction group, n=88) were included. The highest amplitude (any of 12-leads on standard EKG, 10mm/mV, GE Marquette) of the bipolar pacing stimulus on EKG was recorded. Chi-squared analysis was used to compare categorical variables and independent t-test was applied for continuous values. An ROC curve for maximum EKG bipolar pacing stimulus amplitude was generated for prediction of lead functional status (normal versus malfunction).Results:The cohort (49% females, 34% non-white) had an average age of 67 ± 16 years at implant. Malfunction was chiefly identified by lead noise on routine interrogation, consisting of 61% RA and 39% RV leads with mean pacing output 2.74V at 0.5ms. Mean time to malfunction was 6 ± 4 years post implant. There was significant difference in EKG bipolar stimulus amplitudes at time of failure (15.06 ± 13.533mm, p<0.01) compared to those of normal leads (mean=2.54 ± 1.265mm), but no significant difference in pacing output. ROC curve for the prediction of lead malfunction based on EKG amplitude displayed area under curve=0.93 (95% CI [0.891, 0.969]). Selecting an EKG stimulus amplitude cut-off at 3.5mm for the prediction of lead malfunction demonstrated a sensitivity of 86.4% and a specificity of 76%.Conclusion:The amplitude of a bipolar pacing stimulus on EKG is significantly different among normal functioning leads and those with known malfunction due to insulation breach. We found reasonably good performance of this derived measure at distinguishing among the two groups using a cutoff of 3.5mm for EKG stimulus amplitude. A larger prospective dataset is needed to validate a reliable threshold point.

Introduction:The Micra™ VR leadless pacemaker has demonstrated a high implant success rate and a low rate of complications in both investigational and real-world settings. Although the manufacturer’s product performance reporting suggests a high device survival rate, projected longevity based upon real-world usage has not been assessed.Objective:To summarize device electricals and battery longevity in Micra VR leadless pacemakers in nationwide practice.Methods:A retrospective analysis was performed using Micra VR remote transmissions from the CareLink de-identified database queried on 1 June 2022. A patient’s last transmission ≥ 30 days post-implant was used for analysis. Pacing percentage, electrical performance, and battery longevity were summarized. To standardize the analysis, projected battery longevity was computed by adding the number of years between implant and the device’s last transmission and the projected battery life remaining at last transmission based on device use conditions.Results:Transmissions from 26,698 patients qualified for analysis. Median time from implant to final transmission was 19.8 months (range 1-96.7). Mean pacing capture threshold (PCT) was 0.61 ± 0.50 V (standardized to 0.24 ms) with 92.1% of patients having a PCT ≤1.0 V. Mean pacing impedance and sensing amplitude were 567 ± 118 ohms and 13.7 ± 6.3 mV. Median pacing percentage was 82.3% (IQR: 25.7% - 98.6%) with 43.9% of patients paced >90%. Median projected battery longevity for the overall cohort was 13.7 years (IQR: 12.4 - 15.3 years) with 91.9% of devices exceeding 10 years (Figure). Among patients with >90% pacing burden (N=11,717), median projected battery longevity was 12.6 years (IQR: 11.6-13.4) with 87.2% of devices exceeding 10 years.Conclusions:Real-world performance of the Micra VR leadless pacemaker demonstrates favorable pacing parameters with 92.1% of patients having pacing thresholds of ≤1.0 V and a median projected battery longevity of 13.7 years.

Background:Pacemaker implantation (PMI) remains a common complication after TAVR. While a pre-existing right bundle branch block (RBBB) is consistently the strongest reported risk factor for PMI, most patients with a RBBB will not require PMI after TAVR.Objective:To identify factors associated with a higher risk of PMI after TAVR among patients with pre-existing RBBB.Methods:We identified all patients at a single institution undergoing first-time TAVR with a balloon-expandable prosthesis without a pre-existing pacemaker or ICD, and pre-existing RBBB (defined as RBBB morphology with QRS >=110ms) from December 2013 to December 2020 (n=219). We evaluated the univariate association for numerous clinical, EKG, imaging, and procedural characteristics with PMI. We included all factors with p=<0.10 in a logistic regression model to assess for independent associations with PMI in the original cohort and 1000 bootstrapped samples.Results:A history of syncope, body mass index, calcium channel blocker use, baseline PR interval, and prosthesis oversizing >16% were associated with PMI on univariate analysis. When included in a logistic regression model, syncope (OR 3.2, 95%CI: 1.1-8.8, p=0.027) and oversizing (OR 3.1, 95% CI: 1.4-6.8, p=0.005) remained independently associated with PMI. These findings were consistent in the bootstrapped samples. Those with both factors (n=4) had a PMI rate of 75% which was higher compared to those with one or neither (43% and 22%, respectively; p<0.001).Conclusion:Among those with pre-existing RBBB, a history of syncope and prosthesis oversizing >16% were independently associated with a higher risk of PMI. These findings warrant external validation.

Introduction:The randomized PRAETORIAN trial demonstrated non-inferiority of the subcutaneous implantable cardioverter-defibrillator (S-ICD) compared to the transvenous ICD (TV-ICD) with regard to inappropriate shocks and complications. Due to its extrathoracic position, the S-ICD lacks the possibility to provide antitachycardia pacing (ATP) which might result in more appropriate shock therapy. In this pre-specified secondary analysis, we aim to compare first occurrence of appropriate therapy in the S-ICD and TV-ICD.Methods:The PRAETORIAN trial is an international, multicenter, randomized trial (NCT01296022) in which 849 patients with a class I or IIa indication for ICD therapy and without the need for pacing were randomized in a 1:1 ratio to receive either an S-ICD (n = 426) or a TV-ICD (n = 423). Analyses were performed in the modified intention-to-treat population, which included patients according to the group to which they had been randomly assigned regardless of the device they received, but excluded patients who did not receive any ICD.Results:At a median follow-up of 49.1 months, 164 patients received appropriate therapy, of whom 86 in the S-ICD group and 78 in the TV-ICD group (48-month Kaplan-Meier estimated cumulative incidence 19.4% and 17.5%, respectively; hazard ratio 1.12; 95%CI, 0.83 to 1.53; p=0.45). In 83 patients (97%) in the S-ICD group the first arrhythmia was treated with a shock and in 3 patients (3%) with ATP. In 25 patients (32%) in the TV-ICD group the first arrhythmia was treated with a shock, in 31 patients (40%) solely with ATP and in 22 patients (28%) with ATP followed by a shock.Conclusions:In this secondary analysis of the PRAETORIAN trial, we found no statistical difference in first occurrence of appropriate therapy in the S-ICD group and TV-ICD group. Due to ATP, patients were less often treated with shocks in the TV-ICD group. A further analysis of all appropriate therapy in the PRAETORIAN trial could reveal the true benefit of ATP.

Introduction:Device-related infection is estimated to occur in 1.9% of the Medicare patients with de novotransvenous (TV) implantable cardioverter-defibrillators (ICD) within 2 years post-implant. TV-ICD infection is a serious complication that frequently requires complete device removal for attempted cure, which can be associated with patient morbidity and mortality. The objective of this study is to expand on limited published data and assess mortality risk associated with TV-ICD infection in a large Medicare population with de novoTV-ICD implants.Methods:A survival analysis was conducted using 100% fee-for-service Medicare facility-level claims data to identify patients who underwent de novoTV-ICD implantation between 7/2016 and 1/2018. TV-ICD infection within 2 years of implantation was identified using ICD-10 and CPT codes. Baseline patient risk factors associated with mortality were identified using the Charlson Comorbidity Index categories. Infection was treated as a time-dependent variable in a multivariate Cox proportional hazards model to account for immortal time bias.Results:Among 26,742 Medicare patients with de novoTV-ICD, 518 (1.9%) had a device-related infection. The overall number of decedents was 4,721 (17.7%) over 2 years, with 4,555 (17%) in the non-infection group and 166 (32%) in the infection group. After adjusting for baseline patient demographic characteristics and various comorbidities, the presence of TV-ICD infection was associated with an increase of 2.4 [95% CI: 2.08-2.85] times in the mortality hazard ratio (see attached Figure). Most of the baseline patient risk factors were also associated with higher risk of mortality in the Cox model.Conclusion:The rate of de novoTV-ICD infection and associated mortality in a large, real-world Medicare population is noteworthy. The positive association between device-related infection and risk of mortality further highlights the need to reduce infections.

Introduction:The PRAETORIAN trial has investigated the difference in complications between the subcutaneous implantable cardioverter-defibrillator (S-ICD) and the transvenous ICD (TV-ICD). Retrospective studies suggest that women experience more ICD-related complications, specifically related to the lead, than men. We aimed to evaluate this gender difference as a subanalysis of the PRAETORIAN trial.Methods:The PRAETORIAN trial (NCT01296022) is an international multicenter randomized trial. Patients with a class I or IIa ICD indication with no need for pacing therapy were randomized 1:1 to receive either an S-ICD or a TV-ICD and followed for a median of 49.1 months. ICD-related complications included all complications related to the lead or generator that led to medical or surgical intervention. Lead-related complications were defined as complications directly caused by insertion or chronic placement of the ICD lead, or leading to extraction, repositioning or replacement of the ICD lead.Results:A total of 849 patients were included, of whom 167 (19.7%) were female. ICD-related complications occurred in 6/89 women in the S-ICD group and 11/78 women in the TV-ICD group (HR 0.46, 95%CI 0.17-1.25). In men, 25/337 in the S-ICD group and 33/345 in the TV-ICD group had an ICD-related complication (HR 0.77, 95%CI 0.46-1.29). Kaplan Meier curves of both genders are shown in the figure. In Cox regression analysis, women had a higher risk of lead-related complications (HR 2.1, 95%CI 1.04-4.16, p = 0.04).Conclusions:Our prospective data show a more prominent trend in women to experience more ICD-related complications with the TV-ICD. This difference may be due to a significantly higher risk of lead-related complications in women. However, numbers are low and more research is needed to gain more insight into the gender-specific risks and benefits of ICD therapy.

Introduction:Guidelines state that candidates for primary prevention implantable cardioverter-defibrillators (ICDs) should have a ?reasonable expectation? of survival > 1 year. However, tools for predicting survival in this population are lacking.Hypothesis:To investigate predictors of 1 year survival after ICD implantation.Methods:We analysed patients with ICDs in Registry of Atrial Tachycardia and Atrial Fibrillation Episodes (n = 2238). Of these, 2198 (98.2%) had complete information on follow-up. The primary endpoint was survival at 1 year after ICD implantation.Results:Over a median follow up of 1.95 (IQR: 1.0-2.1) years, 168 patients (7.5%) died, of whom 96 (4.2%) died within 1 year. Significant differences were noted in multiple variables between those who did or did not survive 1 year. However, in multivariable analysis, only four variables were significantly associated with 1 year survival: higher New York Heart Association class (hazard ratio [HR] 1.71 per increase in class, 95% confidence interval [CI] 1.12-2.63, p = 0.02), age at implant (HR 1.04 per year, 95% CI (1.01-1.06, p=0.002) and diabetes (HR 1.64, 95% CI 1.01-2.66, p=0.05) were associated with increased risk of death at 1 year. Use of angiotensin antagonists was associated with lower risk of 1 year mortality (HR 0.59, 95% CI 0.39-0.91, p = 0.016). Receiver operating characteristic curve analysis to predict 1 year survival using these variables showed modest discrimination, Figure1.Conclusions:Overall, ~4% of ICD recipients died by 1 year. Although many variables differ between those who do and do not survive 1 year, substantial overlap exists and models to predict survival have limited discrimination. Without better tools to identify which ICD candidates are most or least likely to survive 1 year, ICDs may be withheld due to perceptions of limited survival from those who may potentially benefit. These findings have important implications for guidelines recommendations on device therapy.

Introduction:Resting electrocardiographic (ECG) abnormalities have been shown to be independently associated with coronary heart disease however utility of repolarization and depolarization abnormalities in relation to incident heart failure (HF) remains uncertain.Methods:Population-based cohort from Eastern Finland with 771 men and 840 women, without heart failure with an average follow-up of 14 years. Six electrocardiogram/vector electrocardiogram (ECG/VECG) markers including QRS-duration, QTc-interval, QRST-angle, sum of absolute QRST integral (SAI QRST), T-wave roundness, and TV1-amplitude were estimated from VECG measurements.Results:Overall incident HF was observed in 68 men (8.8 %) and 64 (7.6%) women during a median (IQR) follow-up of 14 (13.1-14.9) years. Hazard ratios (HRs) for incident HF events (132) for ECG/VECG parameter models adjusted for clinical risk factors showed that strongest predictors for incident HF were QRST-angle HR 3.1, 95% confidence interval (CI) 2.12-5.36, QTc-interval HR 2.72, 95% CI: 1.73-4.29, and T-wave roundness HR 2.09, 95% CI: 1.26-3.46 among men. The strongest ECG/VECG parameters for incident HF were QRST-angle HR 3.1, 95% CI: 1.70-5.52, SAI QRST HR 2.73, 95% CI: 1.40-5.30, among females. Findings remained consistent across other clinical subgroups for both genders.Conclusion:Several characteristics of global electrical heterogeneity in men and women were strong and independent risk markers for incident HF events. These parameters provide new additional ECG tools for HF risk stratification.

Introduction:Patients (pts) enrolled in CRT trials have a low reported baseline quality of life (QoL); however, these trials have enrolled primarily men. The AdaptResponse trial is the first large CRT trial well represented with women. Accordingly, the present analysis was designed to assess the relationship between gender and other patient characteristics and QoL.Methods:The AdaptResponse trial enrolled CRT indicated pts with NYHA Class II-IV HF, LBBB (QRS ?140 ms in men, ?130 ms in women), and baseline PR interval ?200ms. Multivariable linear regression was used to assess the relation of baseline Kansas City Cardiomyopathy Questionnare (KCCQ) overall summary score and patient characteristics. Backward selection was used on an initial model with 31 variables and gender interactions. Height and key comorbidities were added back to the model.Results:There were 3620 pts randomized in 226 centers worldwide, including 1569 (43.3%) women. Women had a significantly lower score on most KCCQ domains (Figure), such as in the Physical Limitation (62.4 ? 25.1 versus 72.3 ? 24.3, p<0.001) and in the Clinical Summary domain (63.3 ? 23.1 versus 72.4 ? 22.1, p<0.001). Several clinical characteristics were associated with a lower KCCQ overall summary score, especially higher NYHA class, chronic lung disease, depression, previous HF hospitalization and loop diuretic use (Table). Multivariable analysis showed that women have a 4.89 points lower score than men (p<0.0001).Conclusion:Women undergoing CRT have important differences from men with regard to patient characteristics and baseline QoL. The impact of these differences on clinical outcomes will be evaluated in the AdaptResponse trial.

Introduction:Atrial fibrillation (AF) can be triggered by several etiologies including an acute illness. The short and long-term implications of AF in this setting are poorly studied. Our aim was to identify the incidence and impact of Atrial Fibrillation (AF) in critically ill septic patients.Methods:We conducted a single-center retrospective cohort study of patients admitted with sepsis, septicemia, severe sepsis, and septic shock (ICD-9 codes: 9959.1, 038, 9959.2, 785.0) between 2001 and 2012 utilizing the Medical Information Mart for Intensive Care (MIMIC) database. After reviewing clinical documentation, patients were divided into three groups: septic patients who did not have concomitant AF (control), septic patients with new onset AF and no history of AF (new onset), and patients with AF and known history of AF (recurrent). In-hospital mortality, length of stay (LOS), and stroke incidence were the primary outcomes of interest. Univariate and multivariate analyses (i.e. logistic regression for mortality endpoint and Cox proportional hazards regression) were performed after adjusting for baseline and clinical characteristics.Results:There was a total of 5,037 ICU admissions for sepsis, of which 978 (19%) had AF (recurrent AF: 865, new onset AF: 113). The mean age of all patients was 69 (?13) of which 41% were females. Patients with new onset AF had a significantly longer average length of stay?13.1 days relative to 11.4 days and 11.9 days in recurrent AF and control patients, respectively (p=0.03). In-hospital mortality was 22.1% for septic patients without AF, 21.2% in septic patients with new AF and 18.7% in patients with recurrent AF (p=0.08). In a survival analysis (of in-hospital mortality), there was no significant difference between atrial fibrillation status (log rank p=0.43, see figure 1). Multivariate analyses of both mortality and survival revealed similar findings. The rate of embolic stroke during admission was <1% in patients with AF.Conclusions:In this study population new-onset AF increased LOS, but AF regardless of type did not affect mortality in septic patients.

Introduction:Since gaining FDA approval in 2015, left atrial appendage closure (LAAC) with the Watchman device for patients with nonvalvular atrial fibrillation has been increasingly used. While the average age in most of the landmark clinical trials were between 72 and 74, there has been a significant rise in the frequency of this procedure in younger patients. This study aimed to evaluate baseline characteristics and clinical outcomes of patients who are under 65 years of age who underwent LAAC with the Watchman device.Methods:The Nationwide Inpatient Sample database was queried from the years 2012 to 2016 for percutaneous LAAC (ICD 9: 37.90, ICD 10: 02L73DK). Patients who underwent LAAC via the Watchman device were classified as being either younger or older than 65 years. Chi-square and t-test were used to examine the differences in baseline demographics, clinical characteristics, length of stay, and total hospital cost.Results:The average age in the younger group (n=219) was 56 (?11) while those in the older group (n=1,613) was 77 (?6), and, in total, there were 36.6% females. When compared to older patients, younger patients had fewer comorbidities including hyperlipidemia (43% vs. 52%, p=0.02), ischemic heart disease (42% vs. 50%, p=0.02), and COPD (5.94% vs. 10.85%, p=0.02); however, younger patients were more obese (25.5% vs. 11.28%, p<0.01). In terms of complications, patients in the younger group had significantly higher rates of mechanical ventilation (5.9% vs. 2.2%, p<0.01), thromboembolism (3.2% vs. 0.4%, p<0.01), and cardiac arrest (1.4% vs. 0.4%, p=0.048). Although inpatient mortality was higher in the younger group, there was no significant difference between the two groups (1.4% vs. 0.8%, p=0.4). Interestingly, patients less than 65 years of age had a longer mean length of stay (5.8 vs. 2.7 days, p<0.01) and averaged $49,838 more in hospital charges (p=0.01).Conclusion:This study suggests that percutaneous LAAC is associated with worse outcomes along with longer hospitalizations in patients who are less than 65 years compared to older patients. Further prospective studies are needed to evaluate the outcomes of percutaneous LACC in younger patients.

Introduction:The Micra leadless pacemaker was implanted with high success and a low major complication rate in the Micra Post approval registry (PAR). Additionally, there was a low 0.8% overall rate of cardiac perforations, including minor complications and observations. However, whether a low cardiac perforation rate with this new technology will be maintained in a larger real-world patient population remains unknown. The objective of this study was to measure the acute perforation rate with Micra in the Medicare population using administrative claims data.Methods:The Micra Coverage with Evidence Development (CED) Study is a prospective, longitudinal study using administrative claims data of the Medicare fee-for-service (FFS) population implanted with Micra and transvenous single-chamber ventricular pacemakers designed to answer specific questions from the Centers for Medicare and Medicaid Services (CMS). Acute 30-day perforations were identified by ICD-10 diagnosis code for cardiac perforation, pericardial effusion, or cardiac tamponade occurring in any position on a claim and on all claim types (e.g. inpatient, outpatient, and carrier). The acute perforation rate was calculated by dividing the number of patients with a perforation by the total number of Medicare patients who received a Micra implant during the study period.Results:There were 1,757 Medicare FFS patients implanted with a Micra in the first CED cohort, March 9, 2017 to December 1, 2017. Medicare patients included in the Micra CED represent a clinically complex real-world patient population with multiple comorbidities (e.g. 55% with heart failure, 14% on dialysis), concomitant procedures (10%), previous implantation with transvenous pacemakers (36%), and admissions via the Emergency Department (13%). There were 19 (1.1%) acute perforations within 30 days of device implant in the Micra CED.Conclusions:Micra Medicare patients represent a large and clinically complex real-world patient population. Despite this, the acute perforation rate in the CED is in-line with the rate previously reported in the Micra PAR (1.1% vs. 0.8%, respectively).