Comparison of short-term mortality risk factors for valve replacement versus coronary artery bypass graft surgery

Risk factors for 30-day operative (short-term) mortality following coronary artery bypass graft (CABG only) procedures are well established. However, little is known about how the risk factors for short-term mortality following valve replacement procedures (with or without a CABG procedure performed) compare with CABG only risk factors. Department of Veterans Affairs (VA) records (65,585 records) were collected from October 1991 through March 2001 and analyzed. Risk factors for short-term mortality were compared across three subgroups of patients: CABG only surgery (n = 56,318), aortic valve replacement (AVR) with or without CABG (n = 7450), and mitral valve replacement (MVR) with or without CABG (n = 1817). Multivariable logistic regression analyses were used to compare the relative magnitude of risk for 19 candidate predictor variables across subgroups. Only three patient baseline characteristics differed significantly in magnitude of risk between the procedure groups. Partially or totally dependent functional status significantly increased the risk of short-term mortality for AVR patients (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.29–2.09) and MVR patients (OR 2.21, 95% CI 1.48–3.30), but not for CABG only patients (OR 1.04, 95% CI 0.93–1.16). Conversely, previous heart surgery and New York Heart Association functional class III or IV symptoms conferred greater magnitude of risk for CABG only patients compared with the valve subgroups. Overall, the risk factors for short-term mortality following valve replacement and CABG surgery appear to be relatively consistent. However, clinicians should be aware of the importance of preoperative functional status as a unique predictor of mortality following valve surgery.