Clinical Impact of the Volumetric Quantification of Ventricular Secondary Mitral Regurgitation by Three-dimensional Echocardiography

Background The assessment of ventricular secondary mitral regurgitation (v-SMR) severity through effective regurgitant orifice area (EROA) and regurgitant volume (RegVol) calculations using the proximal isovelocity surface area (PISA) method and the two-dimensional echocardiography volumetric method (2DEVM) is prone to underestimation. Accordingly, we sought to investigate the accuracy of the three-dimensional echocardiography volumetric method (3DEVM) and its association with outcomes in v-SMR patients. Methods We included 229 patients (70 ± 13 years, 74% men) with v-SMR. We compared EROA and RegVol calculated by 3DEVM, 2DEVM, and PISA methods. The endpoint was a composite of heart failure hospitalization and death for any cause. Results After a mean follow-up of 20 ± 11 months, 98 patients (43%) reached the endpoint. RegVol and EROA calculated by 3DEVM were larger than those calculated by 2DEVM and PISA. Using ROC curve analysis, both EROA [Area Under the Curve (AUC) 0.75 (95% CI 0.68-0.81)] (p=0.008) and RegVol (AUC 0.75 (95% CI 0.68-0.82) (p=0.02) measured by 3DEVM showed the highest association with the outcome at 2 years compared to PISA and 2DEVM (p<0.05 for all). Kaplan–Meier analysis demonstrated a significantly higher rate of events in patients with EROA≥0.3 cm2 (cumulative survival at two years: 28±7% vs. 32±10% vs. 30±11%) and RegVol≥45 mL (cumulative survival at two years: 21±7% vs. 24±13% vs. 22±10%) by 3DEVM compared to those by PISA and 2DEVM, respectively. In Cox Multivariable Analysis, 3DEVM-EROA remained independently associated with the endpoint (Hazard Ratio: 1.02, 95%CI 1.00-1.05), p=0.02). The model including EROA by 3DEVM provided significant incremental value to predict the combined endpoint compared to those using 2DEVM (NRI=0.51, p=0.003; IDI=0.04, p=0.014) and PISA (NRI=0.80, p<0.001; IDI=0.06, p<0.001). Conclusions EROA and RegVol calculated by 3DEVM were independently associated with the endpoint, improving the risk stratification of patients with v-SMR compared to 2DEVM and PISA methods.