Insufficient Leaflet Remodeling in Patients With Atrial Fibrillation: Association With the Severity of Mitral Regurgitation.

BACKGROUND The relationship between annular dilatation caused by atrial fibrillation (AF) and mitral regurgitation (MR) remains controversial. We hypothesized that the small ratio of total leaflet area/annulus area (TLA/AA), reflecting insufficient leaflet remodeling to annular dilatation, is a main component of MR in patients with AF. METHODS AND RESULTS Three-dimensional transesophageal echocardiographic data of the mitral valve were analyzed in 28 AF patients with moderate or severe MR (MR group), age- and sex-matched 56 AF patients with mild or less MR (non-MR group), and 16 control subjects. AA was significantly greater in both the MR (645±126 mm2/m2, P<0.001) and non-MR groups (568±121 mm2/m2, P=0.001) compared with control subjects (444±108 mm2/m2). However, TLA/AA was significantly smaller in the MR (1.29±0.10, P<0.001), but not in the non-MR group (1.65±0.24, P>0.99), compared with control subjects (1.70±0.29). In linear regression analysis, TLA/AA was inversely associated with the effective regurgitant orifice (r=-0.73, P<0.001). The area under the receiver-operating-characteristics curve of TLA/AA was significantly greater than that of AA (0.95 versus 0.72, P<0.001). Multivariable analysis revealed that small TLA/AA (P<0.001) was independently associated with significant MR, while AA was not (P=0.26). CONCLUSIONS In patients with AF, insufficient leaflet remodeling to annular dilatation, rather than crude annular dilatation, was strongly associated with the severity of MR.