Pre-existing left bundle branch block and clinical outcomes after transcatheter aortic valve replacement

Background There are currently few reports on pre-existing left bundle branch block (LBBB) in patients undergoing transcatheter aortic valve replacement (TAVR). Nor are there any studies comparing patients with new onset LBBB to those with pre-existing LBBB. This study aimed to investigate the association with pre-existing or new-onset LBBB and clinical outcomes after TAVR. Methods Using data from the Japanese multicenter registry, 5996 patients who underwent TAVR between October 2013 and December 2019 were included. Patients were classified into 3 groups: no LBBB, pre-existing LBBB and new onset LBBB. The 2-year clinical outcomes were compared between 3 groups using Cox proportinal hazard models and propensity score analysis to adjust the differences in baseline characteristics. Results Of 5996 patients who underwent TAVR, 280 patients (4.6%) had pre-existing LBBB and new onset LBBB occurred in 1658 patients (27.6%). Compared with no LBBB group, multivariable Cox regression analysis showed that pre-existing LBBB was associated with a higher 2-year all-cause (adjusted hazard ratio [aHR]: 1.39; 95% confidence interval [CI]: 1.06-1.82; p =0.015) and cardiovascular mortality (aHR: 1.62; 95% CI: 1.05-2.54; p =0.027), but also with higher all-cause (aHR:1.43, 95% CI:1.07-1.91; p =0.016) and cardiovascular mortality (aHR: 1.84, 95% CI: 1.14-2.98; p =0.012) than new onset LBBB group. Heart failure was the most common cause of cardiovascular death, with more heart failure deaths in the pre-existing LBBB group. Conclusions Pre-existing LBBB was independently associated with poor clinical outcomes reflecting increased risk of cardiovascular mortality after TAVR. Patients with pre-existing LBBB should be carefully monitored. What is Known? There are currently few reports on pre-existing left bundle branch block (LBBB) in patients undergoing transcatheter aortic valve replacement (TAVR). Nor are there any studies comparing patients with new onset LBBB to those with pre-existing LBBB. What the Study Add? Patients with pre-existing LBBB not only had a higher mortality than those without LBBB, but also had a worse prognosis than those with new onset LBBB. This was because patients with pre-existing LBBB had more heart failure deaths. Patients with pre-existing LBBB should be carefully monitored after TAVR. Further investigation will be required to corroborate our findings.