Permanent His bundle pacing to replace biventricular pacing for cardiac resynchronization therapy.

Introduction: Cardiac resynchronization therapy (CRT) or biventricular pacing (BIVP) has become a common procedure for the treatment of ventricular dyssynchrony in patients with heart failure, particularly in those with bundle branch block patterns (QRS durations >150ms) on the electrocardiogram (ECG). However, a large group of non-responders are made up of patients with dyssynchrony and QRS duration below 130ms. Recent studies have introduced permanent His bundle pacing as another method for achieving normalization of the QRS duration even in a majority of patients with right or left bundle branch block pattern on the ECG.

Hypotheses: We hypothesize 1. Biventricular pacing, (BIVP) performed as the standard procedure for CRT is inherently abnormal, spatially, at the right and left ventricular apex, and temporally, in regard to the timing of normal activation of the interventricular conduction system. Corollary 1. Permanent, selective, His bundle pacing (PHBP) is the most physiological form of ventricular pacing which replicates the normal activation of the interventricular conduction system. Corollary 2. An appropriately powered, prospective, crossover trial comparing PHBP with BIVP will show that the former is associated with the same benefits in patients with heart failure and QRS durations >130ms and would improve, rather than worsen, outcomes in heart failure patients with QRS duration <130ms. We present experimental and clinical evidence in support of these hypotheses.