Long-Term Prognosis and Outcomes in Patients Undergoing His Bundle Pacing Implantation ― A Multicenter, Prospective Observational Study in Japan ―

BACKGROUND: His bundle (HB) pacing (HBP) can achieve an ideal pattern of ventricular activation. The long-term efficacy and clinical outcomes of HBP in Japan remain unclear. METHODS AND RESULTS: This multicenter prospective observational study enrolled 115 patients undergoing HBP implantation at 8 experienced centers in Japan. Inclusion criteria comprised atrioventricular block or conduction disturbance and an anticipated ventricular pacing of ≥40% in patients scheduled for HBP implantation. All patients were followed for 3 years after implantation. The primary endpoints were all-cause mortality, hospitalization for heart failure, and upgrade to cardiac resynchronization therapy. Secondary endpoints were changes in echocardiographic parameters and laboratory biomarkers after implantation. Seventy-eight (68%) patients continued HBP after the procedure (procedural success), whereas 68 (59%) patients exhibited clinical success (HB capture threshold ≤2.5 V at 1.0 ms). Six months after implantation, echocardiographic parameters improved, and brain B-type natriuretic peptide (BNP) levels decreased substantially. Major adverse clinical events (MACE), defined as the composite of the primary endpoints, occurred in 16 (21%) patients; 18 (23%) patients discontinued HBP during the follow-up period. Multivariable analysis identified elevated BNP levels at baseline as an independent predictor of MACE. CONCLUSIONS: HBP implantation presents technical challenges and exhibits a moderate success rate in real-world clinical practice. The high incidence of elevated HB capture thresholds and HBP abandonment mean that careful patient selection and rigorous long-term surveillance are required.