Clinical Implications of New-Onset Left Bundle Branch Block After Transcatheter Aortic Valve Replacement: Analysis of the PARTNER Experience

Study Questions:

What is the incidence and clinical importance of new and persistent left bundle branch block (LBBB) following transcatheter aortic valve replacement (TAVR)?

Methods:

This study examined 1,151 patients from the PARTNER trial and continued access registries undergoing TAVR with the Edwards SAPIEN or SAPIEN XT balloon-expandable system, and with baseline and discharge/7-day electrocardiograms available, and after exclusion of individuals with prior permanent pacemakers or existing intraventricular conduction delay. The incidence, predictors, and outcomes were compared between patients with versus without new and persistent LBBB.

Results:

New and persistent LBBB occurred in 10.5% (121/1,151) of individuals, and was observed in 6- to 12-month follow-up in 8.5% of patients. Other than a difference in prior coronary artery bypass graft (CABG) surgery, there were no significant differences between groups in baseline patient characteristics, electrocardiogram findings, or echocardiogram findings. Procedural characteristics including procedural success, access route, valve sizing, diameter oversizing, and the need for post-dilation were not associated with the development of LBBB. There were no significant differences between groups in 30-day or 1-year outcomes including mortality, repeat hospitalization, stroke, or myocardial infarction. The need for new permanent pacemaker was higher in patients with versus without LBBB at 30 days (9.9% vs. 2.9%, p < 0.001) and 1 year (12.9% vs. 4.3%, p < 0.001). Individuals with versus without LBBB had similar baseline left ventricular ejection fraction (LVEF) (54.4% vs. 55.4%, p = 0.24), but had differences in LVEF at discharge (53.5% vs. 57.1%, p < 0.001), at 30 days (54.2% vs. 57.2%, p = 0.009), and at 6-12 months (52.8% vs. 58.1%, p < 0.001).

Conclusions:

New and persistent LBBB was observed in 10.5% of individuals undergoing balloon-expandable TAVR. There were no differences between groups in mortality, rehospitalization, stroke, or myocardial infarction, but those with new LBBB had lower LVEF on subsequent imaging, and had higher rates of permanent pacemaker implantation.

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.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, EP Basic Science, Cardiac Surgery and Arrhythmias, Interventions and Imaging, Echocardiography/Ultrasound

Keywords: Myocardial Infarction, Stroke, Bundle-Branch Block, Pacemaker, Artificial, Electrocardiography, Coronary Artery Bypass, Echocardiography


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