Mechanism of atrial functional mitral regurgitation in patients with atrial fibrillation: A study using three-dimensional transesophageal echocardiography.

In patients with AF and significant functional MR occurring despite their preserved LV systolic function, the left atrium and mitral annulus were dilated and the anterior leaflet was flattened along the mitral annular plane, whereas the posterior leaflet was bent toward the LV cavity.