Additional benefits of nonconventional modalities of cardiac resynchronization therapy using His bundle pacing.

INTRODUCTION: Dyssynchrony persists in many patients despite cardiac resynchronization therapy (CRT). Aim of this proof-of-concept study was to achieve better CRT, with a QRS approximating the normal width and axis, by using His bundle pacing (HBP) and nonconventional pacing configurations. METHODS AND RESULTS: In 20 patients with CRT indications, we performed an acute intrapatient comparison between conventional biventricular (CONV) and three nonconventional pacing modalities: HBP alone, His bundle, and coronary sinus pacing (HBP + CS), and HBP + CS plus right ventricular pacing (TRIPLE). Electrical dyssynchrony was assessed by means of QRS width and axis; "quasi-normal" axis meant an R/S ratio ≥ 1 in leads I and V6 and ≤1 in V1. Mechanical dyssynchrony was assessed by speckle tracking echocardiography. QRS width was 153 ± 18 ms on CONV, shortened to 137 ± 16 ms on HBP + CS (P = .001) and to 130 ± 14 ms on TRIPLE (P = .001), while it remained unchanged on HBP (159 ± 32 ms; P = .17). The rate of patients with "quasi-normal" axis was 5% on CONV, and increased to 90% on HBP (P = .0001), to 63% on HBP + CS (P = .001), and to 44% on TRIPLE (P = .02). On radial strain analysis, the time-to-peak difference between anteroseptal and posterolateral segments was 143 ± 116 ms on CONV, shortened to 121 ± 127 ms on HBP (P = .79), to 67 ± 70 ms on HBP + CS (P = .02), and to 76 ± 55 ms on TRIPLE (P = .05). On discharge, HBP was chosen in 15% of patients, HBP + CS in 55%, and TRIPLE in 30%; CONV was never chosen. CONCLUSION: Nonconventional modalities of CRT provide acute additional electrical and mechanical resynchronization. An interpatient variability exists.