The variable spectrum of anterior mitral valve leaflet restriction in rheumatic heart disease screening.

Introduction: The World Heart Federation (WHF) screening criteria do not incorporate a strict, reproducible definition of anterior mitral valve leaflet (AMVL) restriction. Using a novel definition, we have identified two distinct AMVL restriction configurations. The first, called "distal tip" AMVL restriction is associated with additional morphological features of rheumatic heart disease (RHD), while the second, "gradual bowing" AMVL restriction is not. This "arch-like" leaflet configuration involves the base to tip of the medial MV in isolation. We hypothesize that this configuration is a normal variant.

Methodology: The prevalence and associated leaflet configurations of AMVL restriction were assessed in schoolchildren with an established "very low" (VLP), "high" (HP), and "very high" prevalence (VHP) of RHD.

Results: 936 studies were evaluated (HP 577 cases; VLP 359 cases). Sixty-five cases of "gradual bowing" AMVL restriction were identified in the HP cohort (11.3%, 95% CI 8.9-14.1) and 35 cases (9.7%, 95% CI 7-13.2) in the VLP cohort (P = .47). In the second analyses, an enriched cohort of 43 studies with proven definite RHD were evaluated. "Distal tip" AMVL restriction was identified in all 43 VHP cases (100%) and affected the central portion of the AMVL in all cases.

Conclusion: "Gradual bowing" AMVL restriction appears to be a normal, benign variant of the MV, not associated with RHD risk nor with any other morphological features of RHD. Conversely, "Distal tip" AMVL restriction was present in all cases in the VHP cohort with no cases exhibiting a straight, nonrestricted central portion of the AMVL. This novel finding requires further investigation as a potential RHD rule-out test of the MV.