Incidence, Timing, and Determinants of Stroke After Mitral Repair in Patients Without Preoperative Atrial Fibrillation

Background: Increasing use of mitral valve repair has shifted operations to older patients, potentially increasing the post-repair thromboembolic risk. However, the incidence, timing, and determinants of ischemic stroke/transient ischemic attack (TIA) after mitral repair in patients without preoperative atrial fibrillation (AF) remain undetermined. Methods and Results: We retrospectively analyzed 636 patients (mean age, 58±13 years) with degenerative mitral regurgitation and sinus rhythm who underwent mitral valve repair. The primary endpoint was stroke/TIA. Over a mean follow-up of 7.4±5.5 years (4,681 patient-years), 28 (4.4%) developed stroke/TIA. Incidence peaked in the first postoperative year (1.4%/year), declined thereafter, and rose again at 10–15 years (0.67%/year). New-onset AF occurred in 54 patients (8.4%), based on 3,119 ECGs (mean, 4.9±5.8 per patient). Early events (≤1 year) rather than late events (>1 year) occurred in older patients (early vs. late events: 72±8.8 vs. 62±13 years, P=0.052). Later events were associated with larger left atrial size (48±6.7 vs. 41±7.6 mm, P=0.016) and a higher prevalence of new-onset AF (58% vs. 11%, P=0.039). Age ≥70 years (adjusted hazard ratio (HR), 4.4; P<0.001), new-onset AF (adjusted HR, 4.0; P<0.001) and NYHA class (adjusted HR: 2.0, P=0.02) were identified by Fine–Gray regression as independent determinants of stroke/TIA. Conclusions: After mitral repair, ischemic stroke/TIA occurred in 4.4% of patients without preoperative AF, associated with advanced age, new-onset AF, and higher NYHA functional class. This supports close rhythm surveillance and heart failure management.