Comparison of quantitative echocardiographic parameters for grading of mitral regurgitation severity for prediction of clinical outcome

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Abstract Introduction Current recommendations favour the use of quantitative parameters for the assessment of mitral regurgitation (MR) severity and the effective regurgitant orifice area (EROA) derived from the proximal isovelocity surface area (PISA) method has been demonstrated as a predictor of outcome. Purpose The aim of our study was to compare the long-term predictive value of quantitative echocardiographic parameters, derived from the PISA method and volumetric method on clinical endpoints. Methods We retrospectively analysed 298 patients who consecutively underwent echocardiographic examination at out department in 2018 and had been diagnosed with more than mild MR. From the echocardiographic measurements we calculated the quantitative parameters (EROA, regurgitant volume (Rvol) and regurgitant fraction (RF)) by the PISA method and volumetric method (based on the Rvol calculated as a difference between total left ventricular stroke volume derived from the Simpson’s biplane planimetry and forward stroke volume assessed by the pulsed-wave Doppler left ventricular outflow tract method). The clinical outcome was death from any cause, hospitalization due to heart failure or mitral valve intervention in the period from the echocardiographic examination to the end of 2022. Results The study cohort comprised 169 (56%) patients with secondary MR, 103 (35%) with primary MR and 26 (9%) with combined etiology. Clinical endpoints were observed in 198 (66%) patients. Median time to the event was 732 (121-1578) days. Quantitative parameters by the PISA method better predicted the clinical outcome compared to quantitative parameters by the volumetric method (Figure A). RF-PISA had the biggest area under the curve (AUC 0.633, p < 0.001), followed by the EROA-PISA (AUC 0.626, p < 0.001), while the predictive values of quantitative parameters by the volumetric method were not significant (EROA: p= 0.109, Rvol: p=0.153, RF: p=0.156). By the PISA method, patients with RF≥50% had more adverse outcome compared to those with RF<50% (Figure B). By the volumetric method, however, the outcome was similar for both patients with RF≥50% or <50% (Figure B). In our cohort, the best cut-off value for the prediction of the clinical event was RF-PISA >46% (sensitivity 48%, specificity 76%) and EROA-PISA > 0.24 cm2 (sensitivity 41%, specificity 78%). Conclusions Quantitative parameters for grading MR severity by the PISA method provide better diagnostic accuracy for predicting the clinical outcome in comparison to quantitative parameters by the volumetric method. RF-PISA turned out as a good predictor for clinical outcome. Our results show that the fraction of regurgitation better defines the clinical significance of MR than the absolute values of quantitative parameters. Therefore, the RF should be reported as part of the quantitative assessment of MR severity.