What is a better measure of regurgitant severity in secondary mitral regurgitation by echocardiography?

Secondary mitral regurgitation (MR) is a hot topic of cardiovascular field after two randomised trials of transcatheter edge-to-edge repair in patients with secondary MR—Multicenter Study of Percutaneous Mitral Valve Repair MitraClip Device in Patients with Severe Secondary MR (MITRA-FR) and Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional MR (COAPT).1 2 The trials had similar aims, but in COAPT trial, MitraClip was associated with decreased risk of death and hospitalisation for heart failure, and in MITRA-FR, the intervention was not effectiveness for the prognosis. Many investigators try to clarify the difference between two trials.3 4 One possible explanation is the different cohort study between the two trials. From the standpoints of haemodynamic status, the effective regurgitant orifice area (EROA) can be estimated from left ventricular end-diastolic volume (LVEDV), left ventricular ejection fraction (LVEF) and regurgitant fraction (RF) based on the Gorlin hydraulic orifice equation. For example, in a patient with LVEDV of 230 mL, LVEF of 30% and RF of 50%, EROA can be estimated as around 0.3 cm2. If the actual EROA is over the estimated EROA from LVEDV, LVEF and RF, this haemodynamic status …