Site-Specific Differences in Latency Intervals during Biventricular Pacing: Impact on Paced QRS Morphology and Echo-Optimized V-V Interval

Abstract

LV pacing from the lateral cardiac vein is associated with longer latency intervals than endocardial RV pacing. LV latency causes delayed LV activation and requires V-V interval adjustment to improve hemodynamic response to CRT. Patients with LV latency ≥ 40 ms most often display an LBBB pattern in lead V(1) during simultaneous biventricular pacing, but a right bundle branch block after V-V interval optimization.