Mitral Annular Calcification-Related Mitral Stenosis: 5-Year Outcomes and Prognostic Determinants in the JAMAC Study

Abstract

Background: Mitral annular calcification (MAC)-related mitral stenosis is associated with increased mortality, but robust long-term outcomes remain unclear.

Objectives: The aim of this study was to investigate 5-year outcomes, including causes of death and valve-related prognostic factors, in patients with MAC-related mitral stenosis.

Methods: The retrospective, multicenter JAMAC (Japan Multicenter Mitral Annular Calcification) study included adult patients from 11 Japanese centers who underwent echocardiography between 2016 and 2017 and had MAC with a transmitral mean gradient ≥5 mm Hg. Mitral stenosis etiology, mitral valve area (MVA), and anterior MAC in the parasternal long-axis view were evaluated. Posterior MAC was graded as mild (less than one-third), moderate (one-third to two-thirds), or severe (more than two-thirds) of the posterior mitral annular circumference in the parasternal short-axis view. The primary outcome was all-cause mortality; secondary outcomes were cardiac and noncardiac death. To determine valve-related prognostic factors, multivariable analysis was performed including key clinical variables.

Results: Among 264 patients (median age 78 years; 73% female), 201 (76%) had calcific mitral stenosis and 63 (24%) had rheumatic mitral stenosis. Median MVA was 1.40 cm², transmitral mean gradient was 6.1 mm Hg, and 63% had anterior MAC. Posterior MAC was severe in 47% and moderate in 25%. Five-year survival was 57%; cardiac and noncardiac mortality was 16% and 24%, respectively. Calcific mitral stenosis showed higher mortality compared with rheumatic mitral stenosis (cardiac death: 18% vs 11%; noncardiac death: 28% vs 13%). Anterior and severe posterior MAC were associated with increased mortality. MVA <1.5 cm² predicted mortality in calcific mitral stenosis. On multivariable analysis, MVA remained associated with mortality (adjusted HR: 1.56; 95% CI: 1.03-2.38), independent of age and chronic kidney disease, both strong predictors of death.

Conclusions: The prognosis of MAC-related mitral stenosis was poor, with a 5-year survival of 57%, mainly driven by noncardiac mortality in calcific mitral stenosis. Severity of mitral stenosis was one of the independent predictors in this high-risk population.

Keywords: calcific mitral stenosis; degenerative mitral stenosis; echocardiography; mitral annular calcification; mitral valve area; rheumatic mitral stenosis.