Background: The purpose of this study is to examine the effect of previously implanted valve type on hospital mortality in reoperative valve surgery.
Methods: From 1990 to 2005, 743 patients underwent redo valve surgery at our institution. Patients were divided into those who received a mechanical valve during their prior operation (n = 236) and those who received a biological (porcine or pericardial) valve (n = 507). Perioperative data were analyzed retrospectively.
Results: Patients with failing mechanical valves were younger, more likely to be female, and had a higher prevalence of preoperative stroke and atrial arrhythmias, whereas patients with failing biological valves had more hypertension, diabetes mellitus, hyperlipidemia, and chronic obstructive pulmonary disease (all p < 0.05). Mechanical valve explant patients had fewer prior coronary bypass and aortic valve operations, but more mitral surgeries (all p < 0.05). Mechanical patients also had a higher prevalence of endocarditis (p = 0.001) and urgent or emergent surgery (p < 0.001). Hospital mortality was higher among patients undergoing mechanical valve explant by univariate analysis (13% versus 8%, p = 0.04), but not by multivariate analysis (odds ratio 1.6, 95% confidence interval 0.9 to 2.7, p = 0.1). Logistic regression revealed chronic obstructive pulmonary disease, peripheral vascular disease, endocarditis, and urgency of reoperation as independent predictors of hospital mortality.
Conclusions: Explanting mechanical valves are associated with higher perioperative mortality than are tissue valves, likely because of different modes of failure and presentation. A lower risk of mortality for tissue valve reoperation may be an additional factor to consider when patients and surgeons choose a valve prosthesis type.