Right vntricular pulmonary artery coupling in organic mitral regurgitation: diagnostic value of RV TAPSE/SPAP, FWS/SPAP and S'/SPAP

Abstract Background Right ventricular (RV) - pulmonary artery (PA) coupling reflects the capacity of the RV to adapt to afterload and is increasingly recognized as a functional and prognostic marker in mitral valve disease. Noninvasive indices such as TAPSE/SPAP, RV S′/SPAP, and RV free wall strain (FWS)/SPAP seem promising, but their role across different grades of mitral regurgitation (MR) is not well defined. Aim To assess whether RV-PA coupling indices can differentiate between moderate and severe organic MR using transthoracic echocardiography. Methods This retrospective, single-center study included patients with echocardiographically confirmed organic MR evaluated between July 2020 and January 2025 in the echocardiography laboratory of a tertiary hospital. Patients with inadequate image quality, coexistent significant valvular disease, ischemic heart disease, or chronic atrial fibrillation were excluded. RV–PA coupling was assessed using TAPSE/SPAP, RV S′/SPAP, and RV FWS/SPAP. Non-parametric comparisons were performed using the Mann–Whitney U test. Results A total of 71 patients were included: 44 (62%) with severe MR and 27 (38%) with moderate MR. Median age was 71 years in the severe MR group and 67 years in the moderate group. In the severe MR group, 59.1% were male and 40.9% female; in the moderate MR group, 40.7% were male and 59.3% female. RV–PA coupling indices were significantly lower in the severe MR group. TAPSE/SPAP was reduced to a median of 0.39 (interquartile range [IQR] 0.30–0.52) compared to 0.49 (IQR 0.38–0.64) in moderate MR (p = 0.011). Similarly, RV S′/SPAP was lower in severe MR (median 0.26, IQR 0.20–0.34) than in moderate MR (0.33, IQR 0.26–0.41; p = 0.018). RV FWS/SPAP also decreased with MR severity (0.65 [IQR 0.49–0.83] vs. 0.80 [IQR 0.64–1.00]; p = 0.028). Conclusion Echocardiographic indices of RV–PA coupling—TAPSE/SPAP, RV S′/SPAP, and RV FWS/SPAP—were significantly impaired in patients with severe organic MR, even in the presence of similar biventricular systolic function. These indices may enhance early identification of RV–PA uncoupling and support their inclusion in routine MR assessment to refine timing of intervention.