Prevalence and Prognostic Implications of Moderate or Severe Mitral Regurgitation in Patients with Bicuspid Aortic Valve

Background: Significant (moderate or greater) mitral regurgitation (MR) could augment the hemodynamic ef-fects of aortic valvular disease in patients with bicuspid aortic valve (BAV), imposing a greater hemodynamic burden on the left ventricle and atrium, possibly culminating in a faster onset of left ventricular dilation and/or symptoms. The aim of this study was to determine the prevalence and prognostic implications of significant MR in patients with BAV.Methods: In this large, multicenter, international registry, a total of 2,932 patients (mean age, 48 6 18 years; 71% men) with BAV were identified. All patients were evaluated for the presence of significant primary or sec-ondary MR by transthoracic echocardiography and were followed up for the end points of all-cause mortality and event-free survival.Results: Overall, 147 patients (5.0%) had significant primary (1.5%) or secondary (3.5%) MR. Significant MR was associated with all-cause mortality (hazard ratio [HR], 2.80; 95% CI, 1.91-4.11; P < .001) and reduced event-free survival (HR, 1.97; 95% CI, 1.58-2.46; P < .001) on univariable analysis. MR was not associated with all-cause mortality (adjusted HR, 1.33; 95% CI, 0.85-2.07; P = .21) or event-free survival (adjusted HR, 1.10; 95% CI, 0.85-1.42; P = .49) after multivariable adjustment. However, sensitivity analyses demonstrated that significant MR not due to aortic valve disease retained an independent association with mortality (adjusted HR, 1.81; 95% CI, 1.04-3.15; P = .037). Subgroup analyses demonstrated an independent association be-tween significant MR and all-cause mortality for individuals with significant aortic regurgitation (HR, 2.037; 95% CI, 1.025-4.049; P = .042), although this association was not observed for subgroups with significant aortic stenosis or without significant aortic valve dysfunction.Conclusions: Significant MR is uncommon in patients with BAV. Following adjustment for important confound-ing variables, significant MR was not associated with adverse prognosis in this large study of patients with BAV, except for the patient subgroup with moderate to severe aortic regurgitation. In addition, significant MR not due to aortic valve disease demonstrated an independent association with all-cause mortality. (J Am Soc Echocardiogr 2023;36:402-10.)