Early prosthetic valve degeneration with Mitroflow aortic valves: determination of incidence and risk factors

OBJECTIVES: We describe a cluster of early valve degeneration (EVD) in a series of 281 Mitroflow valves implanted during 1999-2013. Patients with EVD were identified as having symptomatic stenosis or regurgitation within 6 years of implantation leading to reoperation. METHODS: Freedom from reoperation was estimated by Kaplan-Meier actuarial analysis. Patient and valve characteristics in the EVD group were compared with those without using univariate and Cox proportional hazard multivariate regression analysis. RESULTS: The rate of actuarial freedom from reoperation was 97% at 6 years and 92.5% at 10 years. The linearized rate of reoperation was 0.7% per patient-year. Ten patients required repeat surgery for EVD. Reoperation occurred from 2 years of implantation in patients with a mean age of 60, compared with 70 in those without EVD. Causes of explantation were stenosis (8), regurgitation (1) and mixed disease (1). The age was the only significant predictor of early degeneration; P = 0.03, hazard ratio = 2.89. Other factors analysed were atrial fibrillation, hypertension, chronic obstructive pulmonary disease, stroke, diabetes, preoperative angina, poor left ventricular function, renal dysfunction and extracardiac arteriopathy. There were no significant postoperative complications or operative mortality in those patients undergoing repeat surgery. CONCLUSIONS: There is an unexplained incidence (3.6%) of EVD resulting in explantation in some patients at 2 years after surgery. Mitroflow valves may not be suited to a younger age population.