Elevated myocardial extracellular volume fraction is associated with the development of conduction pathway defects following transcatheter aortic valve replacement

Background Transcatheter aortic valve replacement (TAVR) has become an established method of aortic stenosis treatment but suffers from the risk of heart block and pacemaker requirement. Risk stratification for patients who may develop heart block remains imperfect. Simultaneously, myocardial fibrosis as measured by cardiac magnetic resonance imaging (CMR) has been demonstrated as a prognostic indicator of ventricular recovery and mortality following TAVR. However, the association of CMR‐based measures of myocardial fibrosis with post‐TAVR conduction disturbances has not yet been explored. Aims We evaluated whether myocardial fibrosis, as measured by late gadolinium enhancement and extracellular volume (ECV) from CMR would be associated with new conduction abnormalities following TAVR. Methods One hundred seventy patients who underwent CMR within 2 months before TAVR were retrospectively reviewed. Septal late gadolinium enhancement (LGE) and ECV measurements were made as surrogates for replacement and interstitial fibrosis respectively. New conduction abnormalities were defined by the presence of transient or permanent atrioventricular block, new bundle branch blocks, and need for permanent pacemaker. Association of myocardial fibrosis and new conduction derangements were tested using receiver operator curve (ROC) and regression analysis in patients with and without pre‐existing conduction issues. Results Forty‐six (27.1%) patients developed post‐TAVR conduction deficits. ECV was significantly higher among patients who experienced new conduction defects (26.2 ± 3.45% vs. 24.7% ± 4.15%, p value: 0.020). A greater fraction of patients that had new conduction defects had an elevated ECV of ≥26% (54.3% vs. 36.3%, p value: 0.026). ECV ≥ 26% was independently associated with the development of new conduction defects (odds ratio [OR]: 2.364, p value: 0.030). ROC analysis revealed a significant association of ECV with new conduction defects with an area under the receiver operating characteristic curve (AUC) of 0.632 (95% confidence interval: 0.555–0.705, p value: 0.005). The combination of prior right bundle branch block (RBBB) and ECV revealed a greater AUC of 0.779 (0.709–0.839, p value: