Clinical Significance and Prognostic Value of Novel Echocardiographic Index for the Severity of Mitral Regurgitation.

Recently, the left ventricular early inflow-outflow index (LVEIO), calculated by dividing mitral E-wave velocity by the left ventricular outflow velocity time integral, has been proposed as a simple method for evaluating mitral regurgitation (MR). This study determined the optimal LVEIO threshold to assess severe MR with different etiologies and assessed its prognostic value. The records of 18,692 consecutive patients who underwent echocardiography were reviewed. MR was classified into 4 groups: Grade 0/1, no, trivial, or mild MR; Grade 2, moderate MR; Grade 3, moderate to severe MR; and Grade 4, severe MR. The mean (±SD) LVEIO of Grades 0/1, 2, 3, and 4 was 3.6±1.4, 6.0±2.5, 7.4±3.1, and 9.5±2.8, respectively. An optimal LVEIO threshold of 5.4 was determined to distinguish moderate to severe or severe MR from non-severe MR (sensitivity 84%, specificity 91%). Kaplan-Meier survival analysis revealed high mortality in the group with LVEIO ≥5.4 (P=0.009, hazard ratio 1.833). This was found only in primary MR when separate analyses were performed according to etiology. Multivariate analysis revealed that LVEIO was an independent predictor for all-cause death only in primary MR. Using appropriate thresholds, LVEIO is a simple and useful method to diagnose severe MR regardless of etiology. LVEIO can also be useful for predicting prognosis in primary MR.