Prospective, comprehensive assessment of cardiac troponin T testing after coronary artery bypass graft surgery

Abstract

Background: The significance and clinical role of cardiac troponin testing after coronary artery bypass grafting remain unclear.

Methods and results: Cardiac troponin T (cTnT) was measured during the first 24 hours after coronary artery bypass graft surgery in 847 consecutive patients. Only 17 patients (2.0%) had new Q waves or left bundle-branch block after surgery; however, cTnT elevation was observed in nearly all subjects, with a median cTnT concentration of 1.08 ng/mL overall. Direct predictors of postoperative cTnT values included preoperative myocardial infarction (P<0.001), preoperative intraaortic balloon pump (P<0.001), intraoperative/postoperative intraaortic balloon pump (P<0.001), number of distal anastomoses (P=0.005), bypass time (P<0.001), and number of intraoperative defibrillations (P=0.009), whereas glomerular filtration rate (P<0.001), off-pump coronary artery bypass grafting (P=0.003), and use of warm cardioplegia (P=0.02) were inversely associated with cTnT values. A linear association was seen between cTnT levels and length of stay and ventilator hours, and in an analysis adjusted for the Society for Thoracic Surgery Risk Model, cTnT remained independently prognostic for death (odds ratio, 3.20; P=0.003), death or heart failure (odds ratio, 2.04; P=0.008), death or need for vasopressors (odds ratio, 2.70; P<0.001), and the composite of all 3 (odds ratio, 2.57; P<0.001). In contrast to consensus-endorsed cTnT cut points for postoperative evaluation, a cTnT <1.60 ng/mL had a negative predictive value of 93% to 99% for excluding various post-coronary artery bypass graft surgery complications.

Conclusions: cTnT concentrations after coronary artery bypass graft surgery are nearly universally elevated, are determined by numerous factors, and are independently prognostic for impending postoperative complications when used at appropriate cut points.