Optimizing Echocardiographic Evaluation of Chronic Mitral Regurgitation

BACKGROUND The ASE (American Society of Echocardiography) guidelines recommend the presence of at least 4 specific criteria to confirm a diagnosis of definite severe mitral regurgitation (MR). However, the performance of these criteria, particularly when <4 are present, remains unclear. OBJECTIVES This study aims to evaluate and optimize the ASE native MR guidelines by comparing them with quantitative cardiac magnetic resonance (CMR), considered the reference standard for MR assessment. METHODS In this prospective study, 177 patients underwent near-simultaneous CMR and transthoracic echocardiography for the assessment of MR. MR severity was classified using a 4-grade scale based on CMR-derived regurgitant volume, which was calculated as the difference between total left ventricular (LV) stroke volume and aortic forward flow. MR severity was similarly graded using the ASE algorithm, with quantification performed when necessary, by averaging the regurgitant volume from 3 methods: 1) the proximal isovelocity surface area method; 2) the biplane LV volumetric method; and 3) the mitral valve volumetric method. RESULTS The study cohort had a median age of 61.7 years, with 55% being men. Primary MR was the predominant pathology (73% of patients), with 42% having mitral valve prolapse and 25% presenting with flail leaflets. There was exact agreement between transthoracic echocardiography and CMR MR grading in 51% of cases, whereas agreement within 1 grade was observed in 89%. Patients who met any of the ASE severe MR criteria were predominantly classified as having grades 3 to 4 MR by CMR. The following ASE parameters demonstrated high specificity for identifying grade 4 MR by CMR: pulmonary vein systolic flow reversal (specificity 88%), enlarged LV with normal systolic function (specificity 85%), proximal isovelocity surface area radius ≥1.0 cm (specificity 83%), and vena contracta width ≥0.7 cm (specificity 80%). Combining color Doppler with either pulmonary vein systolic reversal or enlarged LV with normal function resulted in 91%-95% specificity for severe MR. Importantly, reliance on fewer ASE criteria reduced the need for quantification from 86% (4 criteria) to 73% (3 criteria) and 59% (2 criteria), thereby enhancing diagnostic efficiency. CONCLUSIONS Certain ASE criteria, especially when used in combination, are highly specific for diagnosing severe MR, even when <4 criteria are present. This study suggests that in many cases, the reliance on extensive quantification may be reduced, streamlining the diagnostic process and improving clinical workflow.