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.

Objectives: Describe an alternative to conventional LV lead placement. Background: Conventional left ventricular (LV) lead placement is not always possible due to anatomic and technical limitations. In selected patients LV endocardial lead placement is a viable alternative. Methods: Five patients on warfarin with unsuccessful coronary sinus lead placements and contraindications to epicardial lead placement elected to undergo addition of an LV endocardial lead. The left ventricle was accessed through the interatrial septum via a combined superior and inferior approach resulting in an active fix lead placed on the LV endocardial surface. Results: All patients underwent successful LV endocardial lead placement. There were no acute procedural complications. Two patients died 2 years following the procedure from unrelated causes. The other patients were alive and well at a mean follow up of 2.8 years, with significant symptomatic improvement and no evidence of cardioembolic complications. Conclusions: The placement of LV endocardial leads is a viable alternative in highly selected patients with limited options.