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

Abstract

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.

Remarkable response to cardiac resynchronization therapy via left bundle branch pacing in patients with true left bundle branch block

“…In our cohort, successful permanent LBBP was achieved in 88% patients with low and stable capture threshold. The capture threshold was much lower and remained stable during follow‐up compared to that under HBP in previous studies 21 …”

“…The capture threshold was much lower and remained stable during follow-up compared to that under HBP in previous studies. 21 The LBB fans out directly from the branching point of His bundle to form a network structure beneath the endocardium of the left side of the interventricular septum, which promises pacing the LBB feasibly and rapidly through an interventricular septal method with significant QRS duration shortening. 22 In the present study, better electrical resynchronization was achieved by LBBP-CRT than BiV-CRT.…”

Is His‐optimized superior to conventional cardiac resynchronization therapy in improving heart failure? Results from a propensity‐matched study

“…in an acute study, observed improved pressure‐volume loops with HBP+LV than with biventricular pacing. Coluccia et al, 5 in an acute cross‐over study, showed a better mechanical resynchronization at echocardiographic radial strain analysis with HBP than with conventional CRT.…”

“…The implantation procedures were carried out in an electrophysiology laboratory equipped with high resolution fluoroscopy with multiple imaging storing possibilities, as described previously 5 . Patients were connected to an electrophysiology device in such a way as to allow simultaneous 12 lead electrocardiogram (ECG) and intracardiac recordings at different sweep speeds.…”

“…Concerning device programming, the interval between HB and LV stimuli was programmed at the same length as the interval between HB stimulus and QRS onset, according to Burri et al 19 ; the interval between RV stimulus and LV stimulus was programmed to the value able to achieve the best “quasi‐normal” axis. A “quasi‐normal” QRS axis was arbitrarily defined as presenting an R/S ratio ≥1 in leads I and V6 and ≤1 in lead V1, suggesting a balanced activation of the LV from the right and left sides and from up to down, as in normal subjects 5 …”