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.

We included 229 patients (70 ± 13 years, 74% men) with v-SMR. We compared EROA and RegVol calculated by the 3DEVM, 2DEVM, and PISA methods. The end point was a composite of heart failure hospitalization and death for any cause.

After a mean follow-up of 20 ±11 months, 98 patients (43%) reached the end point. Regurgitant volume and EROA calculated by 3DEVM were larger than those calculated by 2DEVM and PISA. Using receiver operating characteristic curve analysis, both EROA (area under the curve, 0.75; 95% CI, 0.68-0.81; P = .008) and RegVol (AUC, 0.75; 95% CI, 0.68-0.82; P = .02) measured by 3DEVM showed the highest association with the outcome at 2 years compared to PISA and 2DEVM (P < .05 for all). Kaplan-Meier analysis demonstrated a significantly higher rate of events in patients with EROA ≥ 0.3 cm² (cumulative survival at 2 years: 28% ± 7% vs 32% ± 10% vs 30% ± 11%) and RegVol ≥ 45 mL (cumulative survival at 2 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 end point (hazard ratio, 1.02, 95% CI, 1.00-1.05; P = .02). The model including EROA by 3DEVM provided significant incremental value to predict the combined end point compared to those using 2DEVM (net reclassification index = 0.51, P = .003; integrated discrimination index = 0.04, P = .014) and PISA (net reclassification index = 0.80, P < .001; integrated discrimination index = 0.06, P < .001).

Effective regurgitant orifice area and RegVol calculated by 3DEVM were independently associated with the end point, improving the risk stratification of patients with v-SMR compared to the 2DEVM and PISA methods.

Comparison of 3DEVM, 2DEVM, and PISA to assess MR severity in patients with v-SMR. The 3DEVM-derived EROA and RegVol reclassified v-SMR severity and were associated with a better discriminatory power of patient risk compared to 2DEVM and PISA. (A) Time-dependent ROC curve used to identify the values of EROA (left) and RegVol (right) most closely associated with the composite end point by 3DEVM, 2DEVM, and PISA over a span of 2 years. (B) Spline curve showing the effect of EROA on the composite outcome within the v-SMR cohort. The dashed line showing an RR of 1 represents the average cohort risk of experiencing events. An excess of cardiovascular events (RR > 1) is observed among v-SMR at EROA values of 0.16 cm², 0.06 cm², and 0.07 cm² for 3DEVM, PISA, and 2DEVM, respectively. CSA, Cross-sectional area; LVOT, left ventricular outflow tract; PkVreg, peak velocity of the regurgitant jet; Va, aliasing velocity; VTI, velocity-time integral.