Clinical implications of new-onset left bundle branch block after transcatheter aortic valve replacement: analysis of the PARTNER experience

Cardiac conduction disturbances, including a left bundle branch block (LBBB), occur frequently following transcatheter aortic valve replacement (TAVR) and may be associated with adverse clinical events. This analysis examines the incidence and implications of new onset, persistent LBBB in patients undergoing TAVR with a balloon-expandable valve. Patients undergoing TAVR in the Placement of Aortic Transcatheter Valves (PARTNER) trial and continued access registries with baseline and discharge/7-day electrocardiograms were included. Prior permanent pacemaker implantation (PPI) and baseline intraventricular conduction abnormalities were exclusion criteria. Predictors of new LBBB were identified and outcomes compared between patients with and without new LBBB. New LBBB occurred in 121 of 1151 (10.5%) patients and persisted in more than half at 6 months to 1 year. The only predictor of new LBBB was prior coronary artery bypass grafting. New LBBB was not associated with significant differences in 1-year mortality, cardiovascular mortality, repeat hospitalization, stroke, or myocardial infarction. However, it was associated with increased PPI during hospitalization (8.3 vs 2.8%, P = 0.005) and from discharge to 1 year (4.7 vs. 1.5%, P = 0.01). The ejection fraction failed to improve after TAVR in patients with new LBBB and remained lower at 6 months to 1 year (52.8 vs. 58.1%, P < 0.001). Persistent, new-onset LBBB occurred in 10.5% of patients without intraventricular baseline conduction who underwent TAVR in the PARTNER experience. New LBBB was not associated with death, repeat hospitalization, stroke, or myocardial infarction at 1 year, but was associated with a higher rate of PPI and failure of left ventricular ejection fraction to improve.