His-pacing versus biventricular pacing for cardiac resynchronization therapy: long-term follow-up from the His-alternative I Trial

Background The His-Alternative I trial was the first randomized European trial to compare cardiac resynchronization therapy (CRT) delivered by His-bundle pacing (His-CRT) with conventional biventricular pacing (BiV-CRT). Objectives To compare long-term lead performance, survival and echocardiographic response between His-CRT and BiV-CRT. Methods Fifty patients with symptomatic heart failure (HF), left ventricular ejection fraction ≤35%, and left bundle branch block were randomized 1:1 to His-CRT or BiV-CRT. Following crossover at implantation, 19 patients received His-CRT and 31 received BiV-CRT. Analyses were conducted by these groups, with five years of follow-up. Outcomes included the occurrence of reinterventions, an endpoint of all-cause mortality or hospitalization for HF, and echocardiographic response (≥15% reduction in left ventricular end-systolic volume compared to echocardiography performed prior to device implantation). Results The median follow-up was 5.3 years (interquartile range: 4.6 to 5.7 years). More lead revisions (37% vs. 3%; p = 0.003) and generator replacements (47% vs. 10%; p=0.005) occurred in the His-CRT group compared to the BiV-CRT group. However, patients in the His-CRT group with implant thresholds ≤2.5 V/1ms had similar rates of reinterventions and similar thresholds over time compared to the BiV-CRT group. The risk of all-cause mortality or hospitalization for HF was similar between groups (Hazard ratio: 0.32; 95% confidence interval: 0.07 to 1.49; p = 0.147) and echocardiographic response was comparable between the two groups (89% in His-CRT and 90% in BiV-CRT; p=1.0) Conclusions His-CRT with low implant thresholds had similar long-term performance compared to BiV-CRT. The two pacing strategies provided comparable echocardiographic response.