New insights on Carpentier I mitral regurgitation from multidetector row computed tomography

The underlying mechanism of mitral regurgitation (MR) because of isolated annulus dilation (Carpentier type I) remains controversial in patients with atrial fibrillation (AF). The present study evaluated changes in mitral valve geometry of patients with AF and structurally and functionally normal left ventricles and mitral leaflets. Grade of MR and left ventricular (LV) function was evaluated with echocardiography. Changes in mitral valve geometry were evaluated with multidetector row computed tomography (MDCT) performed before radiofrequency catheter ablation for AF. From a cohort of 480 patients with drug-refractory AF referred for catheter ablation, 170 patients (mean age 58 ± 10 years, 67% men) with structural and functional normal left ventricles and mitral leaflets were included. The intercommissural and anteroposterior diameter, perimeter, and area of the mitral annulus and left atrial volume were assessed with MDCT and correlated with the grade of MR as assessed with echocardiography. A total of 49 patients (29%) had MR ≥2+. These patients had larger mitral annulus area compared with patients with MR <2+ (665.0 ± 100.6 mm(2)/m(2) vs 530.5 ± 66.6 mm(2)/m(2), p <0.001), whereas LV size and function (ejection fraction 64.9 ± 6.3% vs 63.1 ± 5.7%, p = 0.08) were similar. After adjusting for age, type of AF, hypertension, left atrial volume, and LV end-systolic volume and ejection fraction, the mitral annulus dimensions remained independently correlated with MR ≥2+. In conclusion, in AF patients with structural and functional normal left ventricles and mitral leaflets, MDCT demonstrated that mitral annulus dilation is independently associated with type I MR.