Effect of prior valve type on mortality in reoperative valve surgery

The purpose of this study is to examine the effect of previously implanted valve type on hospital mortality in reoperative valve surgery.

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.

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.

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.