Directional Radial Force Alignment Predicts Pacemaker Implantation After Balloon-Expandable Transcatheter Aortic Valve Implantation: A Computed Tomography-Based Biomechanical Study.
BACKGROUND Conduction disturbances requiring permanent pacemaker (PPM) implantation remain a frequent complication of transcatheter aortic valve implantation (TAVI). This study aimed to evaluate the "Vectorial Angle"-a novel computed tomography (CT)-derived biomechanical parameter-alongside traditional anatomical and electrocardiographic predictors of PPM following balloon-expandable TAVI METHODS: This retrospective cohort study included 67 patients with severe symptomatic aortic stenosis undergoing TAVI with the balloon-expandable Myval system. The Vectorial Angle was defined on pre-procedural CT at the elliptical left ventricular outflow tract (e-LVOT) level as the angular deviation between the minor axis (representing the axis of maximal radial expansion force) and the midpoint of the right coronary to non-coronary (RCC-NCC) commissure (approximating the anatomical course of the conduction system). RESULTS PPM implantation was required in 12 patients (17.9%). In multivariate logistic regression analysis, a narrower Vectorial Angle (OR 0.935 per 1° increment, 95% CI 0.889-0.982; p=0.007) and a shorter membranous septal length (MSL) (OR 0.447 per 1 mm increment, 95% CI 0.241-0.831; p=0.011) emerged as the only independent predictors of PPM requirement. Valve oversizing index was not associated with PPM implantation (p=0.954). Implantation depth was numerically greater in the PPM group but did not reach independent predictor status (p=0.079). Pre-existing right bundle branch block (RBBB) lost independent predictive value after adjustment for these structural parameters. Receiver operating characteristic (ROC) curve analysis for the Vectorial Angle yielded an area under the curve of 0.806 (p=0.001), with an optimal cutoff of ≤52°. CONCLUSIONS The Vectorial Angle is a novel, independent pre-procedural predictor of PPM after balloon-expandable TAVI. This finding highlights that the spatial orientation of the valve's maximal radial force relative to the conduction tissue is a potential anatomical determinant associated with conduction-system vulnerability, complementing conventional anatomical assessments such as MSL.