Using three-dimensional (3D) transesophageal echocardiography (TEE) and isometric handgrip exercise (IHE), we investigated the determinants of exercise-induced mitral regurgitation (MR) according to MR etiologies. Seventy-six patients with more than moderate MR, 40 patients with functional MR (FMR) and 36 patients with degenerative MR (DMR), underwent 3D TEE combined with IHE. Mitral valve (MV) geometry and 3D vena contracta area (3D VCA) were simultaneously evaluated at baseline and during IHE. With regard to exercise-induced MR, Δ3D VCA was calculated as the difference between 3D VCA at baseline and 3D VCA during IHE. IHE caused different changes in MV geometry between etiologies and led to exacerbation of 3D VCA at baseline. Larger Δ3D VCA was observed in the FMR group compared with the DMR group (15.9 ± 10.3 mm2 versus 7.3 ± 4.2 mm2; p < 0.0001). In multivariate analyses, tenting height and 3D VCA were selected as independent factors associated with Δ3D VCA in the FMR group (p = 0.0135 and p = 0.0201, respectively), while flail width was selected as an independent factor associated with Δ3D VCA in the DMR group (p = 0.0066). In conclusion, IHE alters mitral valve geometry and causes exacerbation of MR regardless of MR etiology and the determinants of exercise-induced MR differed between MR etiologies.
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