Strain-Based Assessment of Post-TAVR Left Bundle Branch Block in Bicuspid Aortic Valve Using Patient-Specific Computational Modeling.

Abstract

Purpose: Post-transcatheter aortic valve replacement (TAVR) left bundle branch block (LBBB) is the most common post-TAVR cardiac conduction abnormality (CCA), particularly in bicuspid aortic valve (BAV). Prior computational studies evaluated generalized CCA risk but did not quantify LBBB-specific mechanical injury or compare self-expanding (SE) and balloon-expandable (BE) devices in BAV. This proof-of-concept study established a patient-specific computational framework to (1) quantify mechanical stretch in the left bundle branch (LBB)-adjacent region, (2) identify a preliminary, cohort-specific strain-based separation value associated with post-TAVR LBBB, and (3) compare device-related LBBB risk trends between SE and BE devices.

Methods: Cardiac CT scans from six type I BAV TAVR patients were analyzed (two with LBBB and four without CCA). Patient-specific finite element models incorporated anatomy and leaflet calcification. The LBB region was defined using membranous septum length and anatomical landmarks. Simulations reproduced implantation of deployed SE devices and virtual BE devices at standardized depth. Area-weighted logarithmic strain (LE), contact pressure, oversizing index, eccentricity index, and expansion metrics were computed.

Results: LBB-adjacent LE showed clear separation (0.15-0.24 in LBBB vs. 0.03-0.11 without CCA), with 0.11 as a preliminary cohort-specific separation value. Mean LE was higher with SE than BE devices (0.11 vs. 0.08). Contact pressure showed no consistent association with outcome, suggesting that LE differences reflect multiple contributing factors.

Conclusion: In this six-patient cohort, LBB-adjacent strain clearly separated LBBB from No-LBBB cases, whereas contact pressure showed no consistent relationship with outcome. Larger cohorts and sensitivity analyses are needed to establish its clinical utility for BAV TAVR risk stratification or device selection.