Long-term Survival and Cardiac Troponin T Elevation in On- and Off-Pump Coronary Artery Bypass Surgery

Abstract

The long-term clinical usefulness of conventional coronary artery bypass graft surgery (CCAB) versus off-pump surgery (OPCAB) remains controversial. Long-term survival and elevation in cardiac troponin T (cTnT) concentration following CCAB and OPCAB have not been assessed. We tested the hypothesis that long-term survival rates for CCAB and OPCAB patients were similar when stratified by cTnT concentration. In this prospective cohort, we followed 1511 nonemergency patients with 2- or 3-vessel disease (778 CCAB and 733 OPCAB cases) from a hospital in northern New England to determine if 6-year survival rates for CCAB and OPCAB patients were similar. The patients underwent surgery between 2000 and 2004 by surgeons who used both procedures. Postoperative cTnT elevation was defined as > or =1 ng/mL, the upper quartile of cTnT values. Data were linked to the Social Security Administration Death Master File. Kaplan-Meier analysis and Cox proportional hazards models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI), with adjustments for baseline patient and disease characteristics. Patients were followed for a median of 4.1 years (mean, 4.0 years). Patients were similar with regard to baseline disease characteristics, comorbidities, cardiac history, function, and anatomy. OPCAB was associated with increased rates of postoperative bleeding and with a worse 6-year survival rate compared with CCAB, regardless of cTnT concentration (cTnT <1 ng/mL, P < .013; cTnT > or =1 ng/mL, P = .017). Compared with CCAB patients, the adjusted HR (95% CI) was 1.59 (1.09-2.32) for OPCAB patients with cTnT concentrations <1 ng/mL and 1.93 (1.12-3.31) for OPCAB patients with cTnT concentrations > or =1 ng/mL. Survival is better for CCAB patients than for OPCAB patients, regardless of cTnT concentration. This effect is sustained after multivariable adjustment for baseline mortality risk factors.