Introduction: Adaptive cardiac resynchronization therapy (aCRT) is known to have clinical benefits over conventional CRT. We aimed to compare the effects of aCRT and conventional CRT on electrical dyssynchrony. Methods: We conducted a double-blind, randomized controlled trial in patients receiving CRT for routine clinical indications. Participants underwent cardiac computed tomography and 128-electrodes body surface mapping. We measured electrical dyssynchrony on the epicardial surface using noninvasive electrocardiographic imaging (ECGI) before and 6 months post-CRT. Ventricular electrical uncoupling (VEU) was calculated as the difference between the mean left ventricular (LV) and right ventricular (RV) activation times. An electrical dyssynchrony index (EDI) was computed as the standard deviation of local epicardial activation times. Results: We randomized 27 participants (mean age 64±12 y; 34% female; 53% ischemic cardiomyopathy; LV ejection fraction 28±8%; QRS duration 155±21 ms; strict left bundle branch block (LBBB) in 13%) to conventional CRT (n=15) versus aCRT (n=12). In atypical LBBB (n=11;41%) with S-waves in V5-V6, conduction block occurred in the anterior RV, as opposed to the interventricular groove in those who met the strict LBBB criteria. As compared to baseline, VEU reduced post-CRT in aCRT (median reduction 18.9 (interquartile range 4.3-29.2 ms; P=0.034), but not in conventional CRT (21.4 (-30.0 to 49.9 ms; P=0.525) group. There were no differences in the degree of change in VEU and EDI indices between treatment groups. Conclusion: The effect of aCRT and conventional CRT on electrical dyssynchrony is largely similar.

Introduction: In patients with post-infarct cardiomyopathy and ventricular arrhythmias (VT) necessitating implantable cardioverter defibrillators (ICD) are at risk of recurrent shocks with increased morbidity. Methods and Results: A comprehensive search of electronic databases for all randomized clinical trials that evaluated the role of catheter ablation as a preventive strategy at the time of secondary prevention ICD implantation was performed. Four trials were identified with a total of 505 patients (average age 66.4 ± 9.0 yr; 87.7% were male). Preventive ablation was associated with a significant reduction in appropriate device therapies (shocks and/or anti-tachycardia therapy) (hazard ratio [HR]=0.62; 95% confidence interval [CI]=0.46-0.82; p<0.01), sustained VT (HR=0.74; 95% CI=0.55-0.99; p=0.04) compared to control. There were no differences in inappropriate device shocks (HR=0.80; 95% CI=0.38-1.71), all-cause death (HR=0.93; 95% CI=0.53-1.64), cardiac death (HR=0.63; 95% CI=0.29-1.36), arrhythmic death (HR=0.26; 95% CI=0.05-1.31), or cardiac hospitalization (HR=0.79; 95% CI=0.57-1.11) between strategies. Preventive ablation was associated with improved SF-36 physical component (SMD=2.81; 95% CI-0.53-5.10; p=0.02), but not the mental component (SMD=1.30; 95% CI=-2.06-4.66). Conclusion: Among patients with post-infarct cardiomyopathy and VT, preventive catheter ablation at the time of ICD implantation is associated with a significant reduction of appropriate ICD therapy and sustained VT, and improvement in the physical component of quality-of-life, but no reduction in mortality.