Direct His/LBB Pacing as an Alternative to Biventricular Pacing in Patients With HFrEF and a Typical LBBB: The His-Alternative II Study.

BACKGROUND: Cardiac resynchronization therapy (CRT) in patients with symptomatic heart failure and left bundle branch block (LBBB) can be achieved with biventricular pacing (BIV-CRT) or conduction system pacing (CSP-CRT). OBJECTIVES: The present study examined if CSP-CRT was feasible and noninferior to BIV-CRT. METHODS: A total of 150 patients with symptomatic heart failure, left ventricular ejection fraction (LVEF) ≤35%, and LBBB (Strauss criteria) were included. Patients were randomized 1:2 to either BiV-CRT or CSP-CRT (HIS-CRT or LBB-CRT) and followed for 6 months. The primary endpoint was the relative change in left ventricular end-systolic volume (LVESV). Two patients withdrew their consent before implant. RESULTS: At implantation, 15 patients (15 %) crossed over from the CSP-CRT group to the BiV-CRT group and 1 patient crossed over from BiV-CRT to the CSP-CRT group. Accordingly, 85 patients (57 %) were treated with CSP-CRT (26 His-CRT, 59 patients LBB-CRT) and 63 patients (43 %) with BiV-CRT. For the primary endpoint, intention-to-treat 6-month follow-up LVESV decreased by 35% ± 22% with CSP-CRT vs 34% ± 22% with BiV-CRT (between-group differences 0.9%, 95% CI: -6.0% to 7.8%; P < 0.01 for noninferiority, P = 0.80 for superiority). Furthermore, LVEF increased by 14% ± 8% with CSP-CRT vs 14% ± 9% with BiV-CRT (P = NS). QRS duration shortening (-31 ± 22 ms vs -31 ± 21 ms), 6-min walking distance increase (37 ± 53 m vs 24 ± 48 m), Minnesota Living with Heart Failure score reduction (-16 ± 18 vs -13 ± 15), NYHA functional class improvement (-0.6 ± 0.6 vs -0.6 ± 0.7), and N-terminal pro-B-type natriuretic peptide reductions (-72 ± 152 pmol/l vs -110 ± 116 pmol/l) were similar between groups. CONCLUSIONS: In heart failure patients with LBBB, CSP-CRT was noninferior to BiV-CRT in reducing LVESV and both treatment modalities provided similar and excellent improvements in LVEF, QRS duration, heart failure symptoms, and functional capacity.