Predictive value of perioperative cardiac Troponin I for adverse outcome in coronary artery bypass surgery

Objectives: Cardiac Troponin I (cTnI) is a well-known marker for myocardial damage in patients undergoing aorto-coronary bypass grafting (CABG) peakin g 6-8 h after aortic declamping. The aim of this study was to evaluate cTnI release in the course of CABG procedures early, i.e. after the cessation o f cardiopulmonary bypass (CPB) in order to recognize unstable cardiac funct ion leading to hemodynamic deterioration and resulting in an adverse outcom e (AO). AO is defined as the onset of myocardial infarction and/or death pe ri/postoperatively. Methods: Five-hundred and forty consecutive patients wh o underwent CABG were evaluated for cTnI release immediately prior to the i nduction of anesthesia (END) and after termination of CPB (END). Standard C PB with ante/retrograde cold blood cardioplegia was used. Patients with any of the following criteria were excluded: (1), CABG within 7 days of myocar dial infarction; (2), emergency operation for both unstable angina and for coronary occlusion at angioplasty; (3), CABG with concomitant surgical card iac procedures; (4), preoperative renal dysfunction requiring hemodialysis; (5), redos. Troponin I was measured with the Stratus CS(TM) fluorometric e nzyme immunoassay analyzer (Dade-Behring) running on site in the operation room (OR), so values of cTnI could be obtained within 15 rein. Results: The re were six deaths (1.1%) in the entire series, Q-wave myocardial infarctio n occurred in 19 patients (3.5%), AO was experienced by 21 patients (3.9%). The mean preoperative cTnI level was 0.04 +/-0.17 ng/l (mean standard devi ation) for the entire group. The END cTnI level for the AO-group was 0.91 /-0.5 ng/l; for all other patients, this was 0.37 +/-0.3 n/l (P<0.001). Cha nges in intraoperative cTnI levels relative to time course showed a marked increase for the AO-group (0.0038<plus/minus>0.0035 ng/l*min) as compared w ith non-AO patients (0.0019 +/-0.0015 ng/l min; P=0.028). The receiver oper ating characteristic curve indicates a cTnI level at CPB-end of higher than 0.495 ng/l with an area under the curve of 0.83 as the optimal cut-off poi nt for predicting AO with a sensitivity and specificity of 76.2%. Stepwise logistic regression analysis revealed END cTnI level (odds ratio, 17.24; P< 0.001), CPB time (odds ratio, 1.03; P=0.001), female sex (odds ratio, 3.8; P=0.011) as significant independent predictors for AO. Age of over 70 years (P=0.8), Cleveland Clinic risk score (P=0.65), diabetes (P=0.26), elevated preoperative creatinine level (P=0.77), severe left ventricular dysfunctio n (P=0.51), the number of grafts performed (P=0.15), and change of intraope rative cTnI level relative to time course (P=0.94) did not reach statistica l significance. Conclusions: cTnI release as determined at the end of CABG procedures represents a strong predictor of an AO after surgery. Analyzing blood samples for cTnI with an automated device on site in the OR provides for immediate results, so specific diagnostic and therapeutic interventions can be performed before hemodynamics deteriorate. (C) 2001 Elsevier Scienc e B.V. All rights reserved.