Background: Premature ventricular contractions (PVCs) are frequently observed with left ventricular (LV) systolic dysfunction, although the prevalence of these associated conditions in the general population remains unknown. Objective: We sought to understand the prevalence of frequent PVCs (defined PVCs>5%) and high burden PVCs (defined PVCs>10%) and LV systolic dysfunction in patients receiving ambulatory Holter monitors (HM). Methods: A prospective multicenter (8 US medical centers) cross-sectional study collected demographic and PVC burden data from consecutive patients undergoing 24-hour, 48-hour, and 14-day HM (July 2018-June 2020). Left ventricle ejection fraction (LVEF) data was collected if obtained within 6 months of HM. Four PVC burden groups were analyzed (<1%, 1-5%, 5.1-10% and >10% burden) and stratified by normal LVEF (≥50%) or presence LVEF<50%. Results: The prevalence of PVC burden of 5.1-10% and >10% was 4% and 5%, respectively in the population undergoing HM (n=6,529). Age was significantly different between PVC groups (p<0.001). In those with LVEF assessment (n=3,713), the prevalence of LVEF<50% and both LVEF<50% and PVC>5% was 16.4% and 4.2%, respectively. The prevalence of PVC>5% and PVC>10% in patients with LVEF<50% was 26% and 16%, respectively. PVC>5% were more prevalent in older, male, and Caucasians (p<0.001). Females had a lower prevalence of PVC>5% than males (6% vs. 11%; p<0.001), but not among those with LVEF<50% (24% vs. 26%, p=0.10). Conclusion: PVC>5% and PVC>10% and LVEF<50% are prevalent in patients undergoing HM. PVC>5% are associated with older age. Females have a lower prevalence of PVC>5% than males but similar combined PVC>5% and LVEF<50%.

Introduction: The prognosis of mixed cardiomyopathy (CMP) in patients with implanted cardioverter-defibrillators (ICDs) has not been investigated. We aim to study the demographic, clinical, device therapies and survival characteristics of mixed CMP in a cohort of patients implanted with a defibrillator. Methods: The term mixed CMP was used to categorise patients with impaired left ventricular ejection fraction attributed to documented non-ischemic triggers with concomitant moderate coronary artery disease. This is a single center observational cohort of 526 patients with a mean follow-up 8.7±3.5 years. Results: There were 42.5% patients with ischemic cardiomyopathy (ICM), 26.9% with non-ischemic cardiomyopathy (NICM) and 30.6% with mixed CMP. Mixed CMP, compared to NICM, was associated with higher mean age (69.1±9.6 years), atrial fibrillation (55.3%) and greater incidence of comorbidities. The proportion of patients with mixed CMP receiving device shocks was 23.6% compared to 18.4% in NICM and 27% in ICM. The VT cycle length recorded in mixed CMP (281.6 ± 43.1ms) was comparable with ICM (282.5 ± 44ms; p=0.9) and lesser than NICM (297.7 ± 48.7ms; p=0.1). All-cause mortality in mixed CMP (21.1%) was similar to ICM (20.1%; p=0.8) and higher than NICM (15.6%; p=0.2). Kaplan-Meier curves revealed hazards of 1.57 (95% CI: 0.91, 2.68) for mixed CMP compared to NICM. Conclusion: In a cohort of patients with ICD, the group with mixed CMP represent a phenotype predominantly comprised of elderly with higher incidence of comorbidities. Mixed CMP resembles ICM in terms of number of device shocks and VT cycle length. Long-term prognosis of patients with mixed CMP is worse than NICM and similar to ICM.

Background: The subcutaneous implantable-cardioverter defibrillator (S-ICD) is an appealing alternative to transvenous ICD systems. However, data on indications for S-ICD explantations are sparse. Objectives: To assess incidence and indications for S-ICD explantation at a large tertiary referral center. Methods: We conducted a retrospective study of all S-ICD explantations performed from 2014 to 2020. Data on demographics, comorbidities, implantation characteristics, and indications for explantation, were collected. Results: A total of 64 patients underwent S-ICD explantation during the study period. During that time, there were 410 S-ICD implantations at our institution of which 53 (12.9%) were explanted with a mean duration from implant to explant of 19.7±20.1 months. The mean age of the patients at explantation was 44.8±15.3 years, and 42% (n=27) were female. The indication for S-ICD implantation was primary prevention in 58% and secondary prevention in 42% of the patients. The most common reason for explantation was infection (32.8%) followed by abnormal sensing (25%) and need for pacing (18.8%). Those who underwent S-ICD explantation for pacing indications were significantly older (55.7±13.6 vs 42.3± 14.6 years, p = 0.005) with a wider QRS duration (111±19 ms vs 98±19 ms, p = 0.03) at device implantation compared to patients who underwent explantation for other indications. Conclusion: Incidence of S-ICD explantation in a large tertiary practice was 12.9%. While infection was the indication for a third of the explantations, a significant number were due to sensing abnormalities and need for pacing. These data may have implications for patient selection for S-ICD implantation.

High power, short duration ablation: at least for the right pulmonary vein carina, maybe not so fastGustavo S. Guandalini, MD a and Francis E. Marchlinski, MD aa Section of Cardiac Electrophysiology, Hospital of the University of Pennsylvania, Philadelphia, PACorresponding author: Dr. Francis E. Marchlinski, Division of Cardiovascular Medicine, Electrophysiology Section, Hospital of the University of Pennsylvania, 3400 Spruce Street, 9 Founders Pavilion, Philadelphia, Pennsylvania 19104. E-mail: [email protected] authors have no conflicts to disclose.Word count: 1,170.This research was supported by the Richard T and Angela Clark Innovation Fund in Cardiovascular Medicine.

The COVID-19 pandemic has had a profound effect on the practice of clinical medicine. Tremendous resources have been poured into caring for patients infected with the virus necessitating a reduction in elective medical procedures. The extent to which physicians have modified their behavior in treating non-COVID-19 patients remains unclear. To address this question, we queried major cardiology vendors (Boston Scientific, Abbott and Biosense Webster) in the Philadelphia region to quantify arrhythmia ablation and cardiac device implantation volumes at 27 hospitals. We observed a significant, inverse correlation between regional COVID-19 cases and cardiac electrophysiologic procedures since the beginning of the US outbreak in late January. Furthermore, we observed that atrial fibrillation ablation and ICD implantation rates dropped more than VT ablation and device generator change rates did consistent with a shift away from elective medical procedures. These results can inform expected procedural volume load and planning once routine clinical practice resumes.