Clinical Outcomes of Mitral Valve Reoperations in the United States: An Analysis of The Society of Thoracic Surgeons National Database

Background: This study evaluated outcomes of reoperative mitral valve surgery (MVS) in the United States. Methods: Adults undergoing isolated MVS with prior open-heart operation in The Society of Thoracic Surgeons (STS) National Database between July 2011 and September 2016 were included. Urgent or emergent operations as well as all indications and causes for MVS were included. Primary outcomes were operative mortality and morbidity. Multivariable models were used for risk-adjustment, incorporating variables from the STS Valve Risk Model as well as type of prior operation and reoperative approach. Results: A total of 17,195 patients underwent isolated reoperative MVS at 962 centers. The STS predicted risk of mortality was 8.0%, with 20% having an STS predicted risk of mortality greater than 10%. Prior cardiac operations included previous MVS (61%), coronary artery bypass (39%), aortic valve surgery (18%), and tricuspid valve surgery (6%). Operative mortality for the overall study cohort was 6.6%, and postoperative stroke occurred in 2.4%. Observed-to-expected mortality for the overall cohort was 0.82. The strongest independent predictors of operative mortality included salvage operation, preoperative dialysis dependence, congestive heart failure, recent myocardial infarction, and active endocarditis. Prior aortic valve replacement was associated with increased mortality risk, whereas prior MVS reduced mortality risk. Surgical approach did not affect mortality. For patients with prior MVS undergoing elective, non-endocarditis operations, the operative mortality was 3.4%. Conclusions: Despite a high-risk patient profile, surgical outcomes of reoperative MVS were acceptable, particularly in patients with prior MVS and without endocarditis undergoing elective operations.