Perspective:

This study demonstrates that new and persistent LBBB occurs in approximately 10% of patients after TAVR using the Edwards SAPIEN or SAPIEN XT device. Interestingly, with the exception of prior CABG, patient characteristics and echocardiography/electrocardiogram findings were not associated with development of LBBB, suggesting that it may be challenging to identify patients at risk of LBBB prior to TAVR. While not examined in this study, prior literature has reported that valve implantation depth and annular calcification may be able to identify patients at risk of LBBB, and such variables need to be further evaluated. The lack of a mortality difference between those with versus without LBBB is interesting, as prior research has reported that LBBB is associated with increased mortality in patients undergoing surgical aortic valve replacement, and prior data with TAVR have demonstrated mixed results. The present data do not show any significant differences in adverse events other than need for permanent pacemaker, although it remains to be seen whether any differences would be identified on longer-term follow-up. Changes in LVEF are intriguing, as patients with and without new LBBB demonstrated significantly reduced and improved LVEF, respectively, resulting in significant differences in LVEF on follow-up, and suggesting that new LBBB appears to mitigate the improvement in LVEF observed with non-LBBB individuals. Nevertheless, these changes in LVEF did not correlate to differences in heart failure symptoms or exercise tolerance, suggesting that these differences may not be clinically meaningful. This study improves our understanding of LBBB in patients undergoing balloon-expandable TAVR, and raises questions for future research.