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.