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

Abstract

BackgroundQuantification 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.MethodsA 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.ResultsLVEIO 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.ConclusionLVEIO is a simple yet specific Doppler echocardiographic parameter for estimation of severity of MR including that of rheumatic etiology.

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

“… 18 We assume the reason for this difference is the etiology of MR in the study cohort. Rheumatic heart disease was present in more than half the subjects of the previous study, 18 and there was a predisposition for high E-wave velocity with comorbid mitral stenosis.…”

“…5 At the same time, the revised guidelines note that the PISA method may underestimate MR severity due to the elliptical regurgitant orifice in patients with secondary previous study. 18 We assume the reason for this difference is the etiology of MR in the study cohort. Rheumatic heart disease was present in more than half the subjects of the previous study, 18 and there was a predisposition for high E-wave velocity with comorbid mitral stenosis.…”

“…18,692 patients were classified into different grades according to the severity of MR: 17,960 Grade 0/1 (no, numbers or percentages. Statistical analyses were performed using t-tests for normally distributed parameters, the Mann-Whitney U-test for parameters with a skewed distribution, and the Chi-squared test for appropriate comparisons.…”

The RVEIO and RV function: More, please

“…The concept of RVEIO came from the recently‐derived left ventricular early inflow‐outflow (LVEIO) index, described in 2015 as a simplified construct relating to regurgitant fraction in severe mitral regurgitation (MR) 5–7 . Conventionally, mitral regurgitant volume can be calculated as the difference between the total inflow volume crossing the mitral valve in diastole from the smaller outflow volume that exits the LVOT in systole.…”

“…The concept of RVEIO came from the recently-derived left ventricular early inflow-outflow (LVEIO) index, described in 2015 as a simplified construct relating to regurgitant fraction in severe mitral regurgitation (MR). [5][6][7] Conventionally, mitral regurgitant volume can be calculated as the difference between the total inflow volume crossing the mitral valve in diastole from the smaller outflow volume that exits the LVOT in systole. In the LVEIO numerator, the peak velocity of the inflow wave, E ("early" diastolic), is a surrogate for total inflow and reflects the sum of the pulmonary venous flow and the prior beat's regurgitant volume that initially crosses the mitral orifice and relates to the severity of MR.…”