Yoram Rudy

Introduction Biventricular pacing (BiVp) improves outcomes in systolic heart failure patients with electrical dyssynchrony. BiVp is delivered from epicardial left ventricular (LV) and endocardial right ventricular (RV) electrodes. Acute electrical activation changes with different LV‐RV stimulation offsets can help guide individually optimized BiVp programming. We sought to study the BiVp ventricular activation with different LV‐RV offsets and compare with 12‐lead ECG. Methods In five patients with BiVp (63 ± 17‐year‐old, 80% male, LV ejection fraction 27 ± 6%), we evaluated acute ventricular epicardial activation, varying LV‐RV offsets in 20 ms increments from −40 to 80 ms, using electrocardiographic imaging (ECGI) to obtain absolute ventricular electrical uncoupling (VEUabs, absolute difference in average LV and average RV activation time) and total activation time (TAT). For each patient, we calculated the correlation between ECGI and corresponding ECG (3D‐QRS‐area and QRS duration) with different LV‐RV offsets. Results The LV‐RV offset to attain minimum VEUabs in individual patients ranged 20–60 ms. In all patients, a larger LV‐RV offset was required to achieve minimum VEUabs (36 ± 17 ms) or 3D‐QRS‐area (40 ± 14 ms) than that for minimum TAT (−4 ± 9 ms) or QRS duration (−8 ± 11 ms). In individual patients, 3D‐QRS‐area correlated with VEUabs ( r 0.65 ± 0.24) and QRS duration correlated with TAT ( r 0.95 ± 0.02). Minimum VEUabs and minimum 3D‐QRS‐area were obtained by LV‐RV offset within 20 ms of each other in all five patients. Conclusions LV‐RV electrical uncoupling, as assessed by ECGI, can be minimized by optimizing LV‐RV stimulation offset. 3D‐QRS‐area is a surrogate to identify LV‐RV offset that minimizes LV‐RV uncoupling.