Mitral valve repair and bioprosthetic replacement without postoperative anticoagulation does not increase the risk of stroke or mortality

OBJECTIVES The study aimed to determine if mitral valve repair (MVRR) or bioprosthetic mitral valve replacement (BMVR) without postoperative anticoagulation is associated with a similar risk of thromboembolism and death as anticoagulation. METHODS We retrospectively reviewed our 2004-09 experience in 249 MVRR and bioprosthetic replacement patients (53% female; 63 year mean age). Concurrent procedures principally included antiarrhythmic surgery, aortic valve replacement, tricuspid valve repair and coronary bypass grafting. Warfarin therapy was instituted at the discretion of the surgeon. Thirty-day, a period known to have the highest risk of valve-related thromboembolism, outcomes were compared relying on the incidence of stroke and death as surrogates of thromboembolic complications. Intermediate-term survival was compared between the groups using Cox proportional hazard models. The mean follow-up was 2.9 years. Given the non-randomized warfarin use, a propensity score using patient comorbidities and concurrent procedures was created and added to the Cox models. RESULTS One hundred and ninety-two (77%) patients were discharged on warfarin and 57 (23%) were discharged without warfarin. Thirty-day mortality in patients discharged from the index hospitalization was 1.2% and was similar for the two groups (P = 0.99). Four ischaemic perioperative strokes were detected; 3 in the warfarin group and 1 in the no warfarin group (P = 0.99). Overall survival was 84%, with 84% survival in the warfarin group and 86% in the no warfarin group (P = 0.79). Bleeding complications were comparable between the two groups (P = 0.72). In a multivariate analysis, warfarin was not related to mortality. CONCLUSIONS Despite current guidelines recommending postoperative anticoagulation following MVRR or bioprosthetic replacement, the avoidance of warfarin does not increase perioperative complications and has no impact on intermediate survival. Accordingly, a prospective randomized study to adjudicate the role of extended warfarin thromboprophylaxis in mitral valve surgery is warranted.