Abstract Body (Do not enter title and authors here): Introduction: Transcatheter aortic valve implantation (TAVI) is widely regarded as the treatment modality of choice for the effective and safe treatment of native aortic stenosis among patients with high surgical risk. However, bundle branch block (BBB) following TAVI is well-documented and widely regarded to be the leading complication associated with TAVI, along with other conduction abnormalities such as atrioventricular node block (AVB).

Research question: is the risk of BBB higher with a particular type of TAVI valve compared to the rest?

Aim: To evaluate the risk of developing BBB following TAVI across the different valve types in a systematic and meta-analytic approach.

Methods: The following databases were searched; PubMed, Scopus, Cochrane Library, and ClinicalTrials.gov. We used the following keywords in the search; ((Transcatheter aortic valve implantation OR Transcatheter aortic valve replacement OR TAVI) AND (Bundle branch block OR Right bundle branch block OR Left bundle branch block OR BBB)). The studies were included if they reported the prevalence of BBB in patients undergoing TAVI with a specified type of valve such as balloon-expandable valve (BEV), self-expandable valve (SEV), and mechanical-expandable valve (MEV).

Results: A total of 827 articles were initially identified and eventually only 176 studies were thoroughly reviewed. Finally, 105 articles (55 BEV, 44 SEV and 6 MEV) were included in this systematic review and meta-analysis with a total number of included patients being 65,491. The prevalence of patients who underwent BEV and developed a bundle branch block were 30% (95%CI 0.29-0.31). Moreover, the prevalence of bundle branch block in patients who had a SEV implant were 16% (95% CI 0.16-0.16), whereas patients who underwent a MEV implant had an exceptionally high prevalence of bundle branch block of 54% (95%CI 0.52-0.56). The overall prevalence of BBB in patients undergoing a TAVI was 31% (95% CI 0.17-0.50) using random effects model. Utilization of this model also demonstrated significant heterogeneity (P-value<0.001, I2=100%)

Conclusion: The prevalence of bundle branch block following TAVI is alarmingly high at an overall rate of 31%. More importantly, MEV implants demonstrated a worrisome 54% overall prevalence of bundle branch block, and thus hindering their potential utilization, especially among patients with pre-existing bundle branch block.