Epidemiology and prognostic relevance of morphofunctional classification of secondary mitral regurgitation

Abstract Background Mitral regurgitation has traditionally been divided into organic and functional (FMR) due to its different etiology and prognosis. However, FMR is not a homogeneous entity, and may be secondary to annular dilation, ventricular dilation and dysfunction, or posterior leaflet restriction. Purpose Our aim is to assess the epidemiology of these FMR subtypes and their prognostic impact. Methods Patients with FMR from our center who underwent three-dimensional transesophageal echocardiography (3D-TEE) between 2016 and 2020 were retrospectively evaluated. Patients with at least moderate FMR, effective regurgitant orifice (ERO) by 3D-TEE >0.2 cm2 were selected. They were classified according to the predominant mechanism: type 1 or ventricular dysfunction, type 2 or posterior leaflet restriction, and type 3 or annular dilation. 3D-TEE and the closest transthoracic study variables, as well as baseline demographic and clinical characteristics and evolution events, were obtained and statistical analysis was performed according to FMR types. Results 112 patients were included (66.1% male, mean age 72.3 years). 54.5% had previous hospitalization for heart failure and 53.6% had a history of ischemic heart disease. The most frequently identified FMR mechanism was type 1 (61.6%), followed by type 3 (23.2%) and type 2 (15.2%). There were significant differences in epidemiological factors and echocardiographic parameters (Table) between groups. During follow-up, 43.8% died, received a heart transplant or LVAD and 44.6% had any hospitalization for heart failure. There were no significant differences between FMR types in relation to total mortality (p=0.28), mortality due to heart failure (p=0.13), total hospitalizations (p=0.73), or hospitalization for heart failure (p=0.12). Valvular intervention was performed in 54 patients (48.2%), 33 of them percutaneously with a clip, with no differences in FMR subtypes. Conclusions FMR is a heterogeneous entity and different morphotypes with different epidemiology and etiology can be identified. Despite the different mechanism, all subgroups presented a similar unfavorable prognosis and similar intervention rates.