Baseline right bundle branch block and clinical outcomes in patients undergoing transcatheter aortic valve implantation: a Danish nationwide cohort study.

Aims: In the largest nationwide study of Danish patients undergoing transcatheter aortic valve implantation, we examined the clinical impact of pre-existing right bundle branch block - a known risk factor for permanent pacemaker implantation - on outcomes including pacemaker implantation, heart failure, and all-cause mortality. Methods and results: We included first-time transcatheter aortic valve implantation patients in Denmark from 2008 to 2021. Patients were stratified by baseline right bundle branch block status using the digital Danish Nationwide Electrocardiogram Cohort. The study outcomes were new pacemaker implantation, heart failure, and all-cause mortality at 30, 90, and 365 days. A composite of the study outcomes was also assessed. A total of 4900 patients were included, of whom 438 (9%) had baseline right bundle branch block. Mean age was 81 years, 55% were male. At 90 days, the overall pacemaker implantation incidence was 9%, but markedly higher in the right bundle branch block group: 28.3% vs. 7.1% [hazard ratio (HR) 4.61, 95% confidence interval (CI) 3.60-5.91]. Right bundle branch block was not associated with higher rates of heart failure (10.1% vs. 8.3%; HR 1.23, 95% CI 0.86-1.77) or death (3.7% vs. 3.6%; HR 1.08, 95% CI 0.64-1.82). The findings were consistent at 1 year. Conclusion: In this comprehensive nationwide cohort, right bundle branch block strongly predicted pacemaker implantation after transcatheter aortic valve implantation but importantly, not heart failure or all-cause mortality. The neutral association with heart failure and mortality should be explored further.