Comprehensive assesment of right ventricular function in patients with primary mitral regurgitation.

BACKGROUND

Primary mitral regurgitation (PMR) induces right ventricular (RV) pressure and volume overload, yet RV functional assessment remains challenging with conventional echocardiography due to its complex geometry. The value of four-dimensional automated right ventricular quantification (4D-RVQ) in PMR remains underexplored.

METHODS AND

RESULTS

In this prospective study, 141 participants (36 mild, 31 moderate, 35 severe PMR, and 39 controls) underwent comprehensive echocardiography, including 2D speckle-tracking and 4D-RVQ. The RV-pulmonary artery (PA) coupling index was derived as the ratio of RV free wall longitudinal strain (RVFWLS) to pulmonary artery systolic pressure (PASP). Both 2D and 4D RVFWLS and RV global longitudinal strain showed a significant progressive decline with increasing PMR severity (P < 0.001), outperforming conventional parameters like TAPSE. The RV-PA coupling index demonstrated the strongest correlation with RVEF (r = -0.631, P < 0.001). 4D-RVQ parameters showed good agreement with 2D-derived values. Notably, the 4D RV-PA coupling index exhibited superior discriminatory power for moderate-or-greater PMR (AUC: 0.893, 95% CI: 0.809-0.977), slightly outperforming the 2D index. Despite the preservation of LV ejection fraction even in severe PMR, RV dysfunction was apparent by the moderate stage.

CONCLUSIONS

4D-RVQ provides a comprehensive and sensitive assessment of RV function in PMR. RV strain parameters and the RV-PA coupling index are superior to conventional measures for detecting early RV dysfunction. Its integration into clinical practice can improve the detection of right heart function with significant PMR by directly quantifying the pathophysiological hallmark of RV-PA uncoupling.