Validation of “left ventricular early inflow-outflow index”: A novel echocardiographic method for quantification of mitral regurgitation in an Indian population with special focus on rheumatic etiology

Background: Quantification of mitral regurgitation (MR) has always required an “integrated approach” as there is no single gold-standard method. We investigated a new Doppler-derived parameter “left ventricular early inflow-outflow index (LVEIO)” for the quantification of MR and its likelihood to predict severe MR in correlation with already established parameters in an Indian population including a large subset of patients with rheumatic etiology. Methods: A prospective study was performed at a major tertiary care center in western India over a 5-month period. Five hundred patients diagnosed with isolated MR including 260 (52%) patients with rheumatic etiology were included in the study after applying exclusion criteria. We analyzed MR using color flow jet, effective regurgitant orifice area (EROA), and vena contracta (VC) width. LVEIO is a simplification of the regurgitant volume (RV) method, which was calculated as “E velocity divided by LV outflow velocity integrated over the systolic ejection period left ventricular outflow tract velocity time integral” and compared with the established parameters. Results: LVEIO was 4.65 ± 1.45, 6.56 ± 1.52, and 9.91 ± 3.70 among patients diagnosed with mild, moderate, and severe MR, respectively (p < 0.001). Those with LVEIO ≥8 were the most likely to have severe MR (positive likelihood ratio: 10.42). LVEIO had specificity of 93.25% for diagnosis of severe MR with positive predictive value of 86.36%. There was positive correlation observed between LVEIO and VC width (r = 0.591), RV (r = 0.410), and EROA (r = 0.778) (all p < 0.001) in the Pearson correlation test. The specificity of LVEIO remained consistent in diagnosing severe MR in patients with rheumatic etiology. Conclusion: LVEIO is a simple yet specific Doppler echocardiographic parameter for estimation of severity of MR including that of rheumatic etiology. Keywords: Mitral regurgitation, Doppler echocardiography, Quantificatio