Predictors of high-degree atrioventricular block in patients with new-onset left bundle branch block following transcatheter aortic valve replacement

Background: The development of new left bundle branch block (LBBB) is frequently seen post TAVR and is a known risk factor for progression to high degree AV block. The timing and likelihood of progression into complete heart block is variable and can develop after hospital discharge. We sought to determine predictors for the development of high degree AV block in patients who developed LBBB following TAVR. Methods: All patients between 2014 and 2019 underwent electrophysiology study after developing LBBB post TAVR. Data on these patients including baseline characteristics, echo parameters, EKG variables, HV interval, and the need for subsequent pacemaker implantation were extracted. A prolonged HV interval was defined as ≥ 65 ms. Clinically significant conduction abnormality was defined as development of high-degree AV block or clinically significant complete heart block. Results: Thirty-four patients were included in our study of which 10 (29.4%) developed clinically significant heart block, while 24 (70.6%) did not. The mean HV interval for patients with clinically significant heart block was 70.1 ms vs 57.8 ms for those who did not (p = 0.022). Pre-existing first-degree heart block prior to TAVR (p = 0.026), history of AFib (p = 0.05) in addition to STS score (p = 0.037) were predictors of development of high-degree AV block in our patient population. Conclusions: In patients who develop LBBB following TAVR, HV interval, pre-existing first-degree heart block, and STS score predict progression to high-degree AV block. Performance of a routine electrophysiology study should be considered for high-risk patients who develop LBBB following TAVR.