Effectiveness of left bundle branch area pacing to restore narrow QRS in patients with right bundle branch block

Abstract

Abstract Background/Introduction Left bundle branch area pacing (LBBaP) is an innovative technique used to capture conduction tissue and maintain ventricular synchrony during pacing. There are few data about the efficacy of LBBaP in right bundle branch block (RBBB). Purpose To compare the response to LBBaP, evaluated by the change in QRS duration (QRSd) after pacing, in patients with RBBB, left bundle branch block (LBBB) or without conduction disorder. Methods A total of 162 patients with pacemaker indication underwent LBBaP with stylet driven lead with dedicated sheaths, between November 2020 and April 2023. ECG characteristics were evaluated. Data are presented in mean ± standard deviation (SD) or n (%). Paired sample t-test was used to compare QRSd before and after pacing. Results Indications for pacing were atrioventricular block (AVB) 48,4 %, sinus node dysfunction (SND) 37,7 %, AVB and SND 10,7 % and cardiac resynchronization therapy 3,1 %. LBBaP was successfully performed in 98 % (159/162) of patients (78 ± 10 years, 62 % male). Overall, baseline QRSd was 113,2 ± 26,7 ms and paced QRSd was 112,3 ± 14,8 ms (p = 0,662), with left ventricular activation time (LVAT) of 69 ± 14 ms (table 1). Baseline ECG showed 18 LBBB, 29 RBBB and 11 undetermined conduction disorder. In every kind of conduction disorder, paced QRSd was reduced to < 120 ms (table 2). Notably, paced QRSd was < 120 ms, regardless of baseline QRSd. In patients with most important pre-existing conduction disorder (QRS ≥ 145 ms), an impressive reduction in QRSd was observed (Delta = -40,8 ms , table 1). Conclusion LBBaP with stylet driven lead is an effective approach to obtain short paced QRS regardless of baseline QRSd and of the nature of the initial conduction disorder. This opens new perspectives for cardiac resynchronization in patients with RBBB.