Mitral Annular Function in Mitral Annular Calcification and Severe Mitral Regurgitation

Background

Longitudinal left ventricular (LV) shortening, or mitral atrioventricular plane displacement (AVPD), reflects mitral annular function.

Objectives

The authors sought to demonstrate the use of cardiac computed tomography (CCT) to measure mitral AVPD and assess its contribution to LV stroke volume (LVSV) in patients with mitral annular calcification (MAC), severe functional mitral regurgitation (FMR), and severe primary mitral regurgitation (PMR) without MAC.

Methods

We included 200 patients with circumferential MAC (age 79.6 ± 10 years), 50 with severe FMR (age 74 ± 8 years), 50 with severe PMR (age 83 ± 10 years), and 50 control subjects (age 41.6 ± 16 years) who underwent CCT (2016-2022). AVPD was measured in all patients. The volume of blood attributable to AVPD (V^AVPD) and its fractional contribution to LVSV (SV^AVPD%) were calculated across all cohorts. Group comparisons were performed using t-tests, analysis of variance, and Chi-square tests; multivariable linear regression was used to identify independent associations with AVPD and SV^AVPD%.

Results

Mean AVPD differed significantly between controls, PMR, and FMR patients (11.9, 6.6, 9.9 mm; P < 0.0001), whereas SV^AVPD% was similar (45.8%, 46.5%, 45.5%; P = 0.94). Among MAC patients, AVPD decreased with increasing severity (P < 0.0001). Those with grade 3 to 4 MAC had significantly lower SV^AVPD% compared to non-MAC groups (26.7% to 28.9% vs 45.5% to 46.5%; P < 0.0001). MAC severity was independently associated with reduced AVPD and SV^AVPD% (P < 0.0001).

Conclusions

CCT can quantify mitral annular function and its contribution to LVSV. Moderate-to-severe MAC significantly impairs annular function, reducing its share of LVSV. These findings may inform patient selection for transcatheter mitral therapies that impact annular dynamics.