Aortic Valve and Left Ventricular Outflow Tract Calcium Distribution and Conduction Outcomes After Transcatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis

Permanent pacemaker implantation (PPMI) is an important complication following transcatheter aortic valve replacement (TAVR). The influence of valvular and subvalvular calcium and its distribution between aortic leaflets on the risk of PPMI following TAVR remains unclear. We performed a systematic review of the aortic valve complex (AVC) calcium by leaflet, left ventricular outflow tract (LVOT) calcium by leaflet, total AVC calcium, total LVOT calcium, and mitral annular calcium and its association with post-TAVR atrioventricular block, left bundle branch block, and new PPMI. The search strategy included five databases identifying 893 articles. A total of 34 studies with 11,528 patients were included for qualitative analysis, and seven studies totaling 1056 patients were suitable for quantitative analysis. On meta-analysis, left coronary cusp calcium and right coronary cusp calcium were significant predictors of PPMI, while noncoronary cusp (NCC) calcium was not predictive (left coronary cusp: mean difference: 21.05 mm(3), 95% CI: 5.92-36.19, p < 0.001; right coronary cusp: mean difference: 46.02 mm(3), 95% CI: 1.84-90.21, p = 0.04, and NCC: mean difference: 0.19 mm(3), 95% CI: -0.32 to 0.50, p = 0.10). On qualitative review, LVOT calcium in the NCC region was the leaflet most commonly predictive of post-TAVR conduction outcomes. Total AVC, total LVOT calcium, and mitral annular calcium had no convincing association with post-TAVR conduction outcomes. The distribution of calcium rather than its total volume was associated with post-TAVR conduction abnormalities. Heterogeneity in methodology and implantation techniques between studies limits the clinical significance of these findings.