Sequential His bundle and left ventricular pacing for cardiac resynchronization

Introduction Fusion of left ventricular pacing with intrinsic conduction provides superior resynchronization compared to biventricular pacing. His bundle pacing (HBP) preserves intrinsic conduction and allows for constant fusion with left ventricular pacing. This study evaluated sequential His bundle and left ventricular pacing for cardiac resynchronization therapy (CRT). Methods In patients referred for CRT, sequential His bundle and left ventricular pacing was performed when HBP did not correct the QRS. At implant, QRS duration and area were compared between biventricular pacing and His bundle and left ventricular pacing. Devices were programmed for His and left ventricular pacing. Functional status and echocardiography were evaluated in follow up. Results Twenty-one patients, seven female, 70.7 +/- 9.9 years, 57% with nonischemic cardiomyopathy were included. Baseline QRS duration was 170 +/- 21 ms and was 157 +/- 16 ms with HBP. Biventricular pacing resulted in a QRS duration of 141 +/- 15 ms and decreased to 110 +/- 14 ms with His bundle and left ventricular pacing (p <.0005). His bundle and left ventricular pacing resulted in a smaller paced QRS area (38.5 +/- 22.6 mu Vs) compared to biventricular pacing (67.5 +/- 24.0 mu Vs) and baseline (78.1 +/- 28.1 mu Vs;p <.0005). Left ventricular ejection fraction increased from 27.6 +/- 6.4% to 41.1 +/- 12.5 (at 25 mean months,p = .001) and functional class improved from 3.1 +/- 0.5 to 2.1 +/- 0.8 (at mean 32 months,p <.001). Conclusions Sequential His bundle and left ventricular pacing results in superior electrical synchrony in patients with indication for CRT when HBP does not correct the QRS and resulted in promising clinical and echocardiographic response rates.