Prevalence, characteristics, and long-term outcomes of patients with mitral annular disjunction undergoing surgery for degenerative mitral regurgitation

Abstract Background Mitral valve prolapse (MVP) is associated with progressive mitral regurgitation (MR) requiring surgical repair. A subset of patients with MVP may also suffer from malignant ventricular arrhythmias (VAs), especially in the presence of mitral annular disjunction (MAD). Purpose To assess the prevalence, associated characteristics, and long-term outcomes of patients with MVP with and without MAD undergoing mitral valve surgery for degenerative MR. Methods Patients with MVP and moderate-to-severe or severe degenerative MR undergoing mitral valve surgery between 2010-2022 at a university hospital in Sweden were included. MAD length was measured on echocardiograms at end-systole from the insertion of the posterior leaflet on the detached mitral annulus to the border of the bulging left ventricle. Patient demographics and clinical outcomes were collected from medical records. The primary endpoint consisted of VAs, defined as sustained- or non-sustained ventricular tachycardia or high burden of premature ventricular complexes causing hospitalizations or ablation or identified at Holter monitoring. Other endpoints included sudden cardiac death, all-cause mortality, new onset postoperative atrial fibrillation, stroke, mitral valve reoperation, endocarditis, new or worsened heart failure, myocardial infarction and implantation of permanent pacemaker or cardiac defibrillator. Results Of 599 patients undergoing mitral valve surgery, 96 (16%) had preoperative MAD, with a median (Q1, Q3) MAD length of 8.0 (5.0-10.0) mm. Compared with patients without MAD, patients with MAD were younger (55 vs 63 years), more likely to be female (31% vs 17%), to have diffuse myxomatous valve disease (66% vs 25%) and bileaflet prolapse (57% vs 17%). Most patients underwent mitral valve repair (84% vs 80%). No patient had residual MAD after surgical repair. At a mean follow up time of 5.8 ± 3.5 years after mitral valve repair, VAs were more common in patients with pre-operative MAD (10% vs 2% (adjusted HR 4.52, 95% CI 1.57-13.0)) (Figure 1). There were no significant differences in the risks of other clinical outcomes. Conclusions MAD was associated with almost a 5-fold increased long-term risk of VAs after mitral valve repair despite successful anatomical correction of MAD. These findings highlight the importance of increased awareness of VAs in patients with MAD also after mitral valve surgery.