Cardiac CT-scan for mitral valve calcification assessment before percutaneous commissurotomy: the multicentre prospective CALCIMIT study

Percutaneous mitral commissurotomy (PMC) is the reference treatment for rheumatic mitral stenosis (MS). In high-income countries, mitral valve calcification is frequent. Computed tomography (CT) enables Mitral Valve Calcium Scoring (MVCS), but its prognostic value in rheumatic MS has not been prospectively evaluated. The CALCIMIT study assessed the reproducibility and prognostic value of the MVCS by CT on immediate and long-term outcomes after PMC.

In this prospective multicenter study, patients underwent non-contrast cardiac CT before PMC. MVCS was quantified using Agatston’s method. The primary endpoint was good immediate result (GIR), defined as final mitral valve area ≥1.5 cm² with ≥50% increase and ≤2/4 mitral regurgitation (MR). The secondary endpoint was long-term event-free survival (death or mitral reintervention). Between 2016 and 2019, 172 consecutive patients (mean age 56 ± 15 years; 78% women) were included. According to CT, 113 patients (66%) had mitral calcification. GIR of PMC was achieved in 54.7% of patients. Independent predictors of GIR included lower CT-based MVCS, lower NYHA class, and lower baseline MR grade. MVCS was also independently associated with long-term survival free of mitral reintervention (HR 1.54, 95% CI 1.07–2.21; P = 0.019). A threshold of 385.5 Agatston Units predicted both immediate and late outcomes. Interobserver reproducibility was excellent (calcification detection: Kappa 0.987; MVCS correlation: r = 0.999).

CT-derived MVCS provides independent, reproducible prognostic information for immediate and long-term outcomes after PMC, beyond conventional echocardiographic scores. Integrating MVCS into pre-procedural assessment may improve patient selection for PMC.