Left vs. Normal QRS Axis During Left Bundle Branch Block Induced by Transcatheter Aortic Valve Replacement: 3-Year...

The clinical impact of left QRS axis deviation (LAD) during new-onset left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) remains unclear.

This single-center retrospective study analyzed 254 patients who developed new-onset LBBB during hospitalization after TAVR. Clinical and echocardiographic outcomes were compared between patients with LBBB and LAD (LBBB_LAD) and those with LBBB and a normal QRS axis (LBBB_NA). 96 patients (38%) had LBBB_LAD, defined as a QRS axis <-30°. A more leftward preprocedural QRS axis independently predicted LBBB_LAD (odds ratio 1.20 per 10° decrement; 95% confidence interval (CI) 1.09-1.33; P<0.01). At 3 years, there were no significant differences between groups in all-cause death (28% vs. 19%; P=0.14), cardiovascular death (6% vs. 5%; P=0.73), or heart failure rehospitalization (18% vs. 10%; P=0.07). However, LBBB_LAD was associated with a higher incidence of permanent pacemaker implantation (PPI) for atrioventricular conduction disorder (16% vs. 6%; P=0.02) and remained an independent predictor of PPI (Cox hazard ratio 2.46; 95% CI 1.06-5.73; P=0.04). Echocardiographic measures, including left ventricular ejection fraction, chamber size, and mitral regurgitation severity showed no significant longitudinal differences between groups.

Compared to post-TAVR LBBB_NA, post-TAVR LBBB_LAD is associated with an increased need for PPI, but not with adverse mortality or heart failure outcomes at 3-year follow-up. Closer and extended rhythm monitoring may be warranted in this subgroup.