Anticoagulation with vitamin K antagonists (VKA) is recommended after bioprosthetic mitral valve replacement, because of the anticipated risk of postoperative thromboembolism. The optimal management of antithrombotic therapy at long-term remains uncertain.

Define long-term risk of thromboembolic and bleeding complications after bioprosthetic mitral valve replacement.

From 1984 to 2016, 560 patients underwent mitral valve replacement using the same model of bioprosthesis. Baseline clinical, perioperative and follow-up data were recorded prospectively. We estimated the CHA2DS2-VASc and HAS-BLED risk scores. Incidence of postoperative thromboembolic and bleeding events were compared between various antithrombotic therapies.

Mean age was 69±11 years. The mean follow-up period was 7.3±5.4 years for a total of 4034 valve-years. Follow-up was 98.9% complete. Operative mortality was 3.8%. Patients with AF at discharge were similar to those without AF in age, sex. Antithrombotic strategies at discharge included aspirin in 49%, VKA in 31%, non-VKA oral anticoagulant in 4%, low molecular weight heparin in 4%, none in 12% of patients. At 20 years, the overall actuarial survival rate was 16.9±3.9%. Actuarial freedom from complication at 15 and 20 years was 91.5±2.4% and 83.9±7.6% for thromboembolism, and 91.6±1.7% and 80.2%±10.8% for bleeding event. Age and postoperative atrial fibrillation were associated to higher thromboembolic risk (P<0.05). The risk was even higher in patients with AF at discharge and a CHA2DS2-VASc score ≥3 (HR=4.2; P<0.05).

After bioprosthetic mitral valve replacement, patients with postoperative AF are at high risk of thromboembolism as well as bleeding. Our findings suggest a potential role for non-VKA oral anticoagulants and warrants further randomized study to define the optimal antithrombotic strategy in patients undergoing bioprosthetic mitral valve replacement.