Introduction: Wearable Cardioverter Defibrillator (WCD) is utilized in patients with assumed but not yet confirmed risk for sudden cardiac death (SCD). Many of these patients also present with atrial fibrillation (AF). However, the rate of WCD-detected ventricular or atrial arrhythmia events in this specific high-risk cohort is not well understood. Methods: In WEARIT-II, the cumulative probability of any sustained or non-sustained VT/VF (WCD-treated and non-treated), and atrial/supraventricular arrhythmias during WCD use was assessed using the Kaplan-Meier method by prior AF, with comparisons by the log-rank test. The incidence of ventricular and atrial arrhythmia events were expressed as events per 100 patient-years, and were analyzed by prior AF using negative binomial regression. Results: WEARIT-II enrolled 2000 patients, 557 (28%) of whom had AF prior to enrollment. Cumulative probability of any sustained or non-sustained WCD-detected VT/VF during WCD use was significantly higher among patients with a history of AF than without AF (6% vs. 3%, p=0.001). Similarly, the recurrent rate of any sustained or non-sustained VT/VF was significantly higher in patients with prior AF vs. no prior AF (131.5 events per 100 patient-years vs. 22.7 events per 100 patient-years, p=0.001). Patients with prior AF also had a significantly higher burden of any WCD-detected atrial arrhythmias/SVT/inappropriate therapy (183.2 events per 100 patient-years vs. 74.8 events per 100 patient-years, p<0.001). Conclusion: Our results demonstrate that patients with a history of AF wearing the WCD for risk assessment have a higher incidence of ventricular arrhythmias that may facilitate the decision making for ICD implantation.

Objectives: To evaluate clinical characteristics and prognosis of patients presented with ventricular tachyarrhythmia (VTA) during the course of acute coronary syndrome (ACS) and to analyze it according to period of presentation. Background: VTA is an infrequent yet serious complication of ACS. There is limited data regarding the incidence and prognostic implications of VTA in the last decade as compared with the previous decade. Methods: We evaluated clinical characteristics, major adverse cardiovascular events, short and long- term mortality of patients hospitalized with ACS who were enrolled in the Acute Coronary Syndrome Israeli Survey (ACSIS) during the years 2000-2016. Patients were classified into three groups: no VTA, early VTA (≤48h of onset) and late VTA (>48h of onset). Data were analyzed according to decades of presentation (current decade vs. previous decade). Results: The study population comprised 15,200 patients. VTA occurred in 487 (3.2%) of patients. Early VTA presented in 373/487 (77%) patients and late VTA in 114/487 (23%) patients. VTA’s, occurring in ACS patients were associated with increased risk of in-hospital, 30-days, 1-year and 5-year mortality rates during both early and late periods in compared with no VTA. Moreover, late VTA was associated with the highest mortality rate with up to 65% in 5-year follow up (p<0.001). Nevertheless, late VTA was associated with lower mortality rate in the current decade (2008-2016) compared with last decade (2000-2006). Conclusions: Any VTA following ACS was associated with high short and long-term mortality rate. However, over the past decade there has been a significant improvement in survival rates, especially in patients with late VTA. This may be attributed to early and invasive reperfusion therapy, implantable cardioverter defibrillator implantation and better medical treatment.

Introduction: Cardiac resynchronization therapy (CRT) may be proarrhtyhmic in patients with non-left bundle branch block (non-LBBB). We hypothesized that combined assessment of risk factors (RF) for ventricular tachyarrhythmias (VTA) can be used to stratify non-LBBB patients for CRT implantation. Methods: The study comprised 412 non-LBBB patients from MADIT-CRT randomized to CRT-D (n=215) vs. ICD-only (n=197). Best-subset regression analysis was performed to identify RF associated with increased VTA-risk in CRT-D patients without LBBB. The primary endpoint was first occurrence of sustained VTA during follow-up. Secondary endpoints included VTA/death, and appropriate shock. Results: Four RFs were associated with increased VTA risk: Blood Urea Nitrogen >25mg/dl, ejection-fraction <20%, prior non-sustained VT, and female gender. Among CRT-D patients, 114 (53%) had no RF, while 101 (47%) had ≥ 1 RF. The 4-year cumulative probability of VTA was higher among those with ≥ 1 RF compared with those without RF (40% vs. 14%, p<0.001). Multivariate analysis showed that in patients without RF, treatment with CRT-D was associated with a 61% reduction in VTA compared with ICD-only therapy (p=0.002), whereas among patients with ≥ 1 RF treatment with CRT-D was associated with a corresponding 73% (p=0.025) risk-increase. Consistent results were observed when the secondary endpoints of VTA/death and appropriate ICD shocks were assessed. Conclusion: Combined assessment of factors associated with increased risk for VTA can be used for improved selection of non-LBBB patients for CRT-D.

Introduction – We aimed to assess changes in QTc over time following cardioversion (CV) for persistent atrial fibrillation (AF), and to compare the benefit of using continuous Holter monitoring vs. conventional follow-up. Methods – The study population comprised 90 patients admitted to our center for elective CV due to persistent AF who were prospectively enrolled from July 2017 through August 2018. All patients underwent 7-day Holter started prior to CV. Baseline QTc was defined as median QTc during first hour post CV. The primary endpoint was QTc prolongation defined as QTc ≥500ms, or ≥10% increase (if baseline QTc was >480ms). Conventional monitoring was defined as an ECG recording 2-hours post CV. McNemar test was used for comparison. Results - Mean age was 67 ± 11 years and 61% were male. Median baseline QTc was 452msec (IQ range: 431-479 msec) as compared with a maximal median QTc of 474msec (IQ range: 433–527 msec; p<0.001 for the change in QTc from baseline). Peak median QTc occurred 44-hours post CV. The primary endpoint was met in 3 patients (3%) using conventional monitoring, compared with 39 new patients (43%) using Holter (p<0.001 for comparison). The Holter monitoring was superior to conventional monitoring in detecting clinically significant QTc prolongation (OR=13; p<0.001). Conclusion – CV of patients with persistent AF may be associated with increased transient risk of QTc prolongation. Peak median QTc occurs during end of second day following CV and prolonged ECG monitoring provides superior detection of significant QTc prolongation compared with conventional monitoring