Arrhythmic mitral valve prolapse with versus without prior mitral valve repair: clinical profiles, electrophysiological substrates, and long-term clinical outcomes

Abstract

Abstract Background Arrhythmic mitral valve prolapse (AMVP) is characterized by an arrhythmogenic left ventricular substrate, with high prevalence of myocardial scar. Whether patients with prior mitral valve repair for mitral valve prolapse (MVP) and new-onset complex ventricular arrhythmias (VAs) after cardiac surgery have different electroanatomical substrate and arrhythmic outcomes compared with AMVP patients without prior mitral valve surgery is currently unknown. Purpose We sought to compare the electroanatomical substrate and long-term clinical outcomes of patients with new-onset complex VAs after mitral valve surgery to AMVP patients without prior surgery. Methods We conducted a multicenter, prospective, observational study, enrolling MVP patients with prior mitral valve repair and new-onset complex VAs (>1000 premature ventricular contractions [PVCs]/day, nonsustained ventricular tachycardia [NSVT], and sustained VT) after cardiac surgery (group A,n=9), and patients with MVP, complex VAs and no prior surgery (group B,n=20). Each patient underwent a comprehensive diagnostic workup, including left ventricular electroanatomical mapping. Clinical-imaging data, as well as the location and segmental extension of both low-voltage areas and late potentials were assessed and compared between the two groups. The primary outcome was the occurrence of sustained VT or ventricular fibrillation(VF) during follow-up. Results In group A, complex VAs were first diagnosed after a median of 30(8-56) months following mitral valve repair. The characteristics of patients from the two study groups are presented in the Table. Patients from group A were older, sustained VT was nonsignificantly more common at baseline, the PVC count nonsignificantly higher, and LVEF nonsignificantly lower. Mitral annular disjunction was never observed in group A, while it was found in 7 patients from group B (p=0.066). At LV electroanatomical voltage mapping, bipolar and unipolar low-voltage areas (LVAs) were equally common in the two groups overall, and typically involved basal perimitral regions. However, patients from group B had concomitant bipolar and unipolar LVAs 50% of times, with larger unipolar LVAs, while patients from group A mostly showed isolated bipolar LVAs. Over a median follow-up of 15 (12-41) months, patients from group A (n=3, 33%) had slightly higher incidence of sustained VT or VF (HR: 1.91; 95% CI, 1.06-42.65; log-rank p=0.02, Figure) than patients from group B (n=2, 10%). Conclusion Compared to patients with AMVP and no prior cardiac surgery, patients with new-onset complex VAs after mitral valve repair for MVP have a slightly different clinical profile and electroanatomical substrate, characterized by predominant bipolar LVAs in the perimitral region. The long-term risk of major ventricular arrhythmias appears slightly higher in MVP patients with prior mitral valve surgery, mandating at least an equally careful risk assessment in both groups.