Prognostic value of preoperative cardiac troponin I in patients with non-ST-segment elevation acute coronary syndromes undergoing coronary artery bypass surgery.

STUDY OBJECTIVES: Elevated levels of cardiac troponin I (cTnI) have been associated with adverse short-term and long-term outcomes in acute coronary syndrome (ACS) patients and in patients who underwent coronary artery bypass grafting (CABG); however, the prognostic implications of preoperative cTnI determination have not been investigated so far.

DESIGN AND SETTING: Retrospective study in a department of cardiothoracic surgery of a university hospital.

PATIENTS AND METHODS: A possible correlation between preoperative cTnI levels and major adverse cardiac events (MACE) and in-hospital mortality in CABG patients with non-ST-segment elevation ACS (NSTE-ACS) was investigated. cTnI was determined in 1,978 of 3,124 consecutive CABG patients. Among these, 1,592 patients had preoperative cTnI levels < 0.1 ng/mL and therefore served as control subjects (group 1), 265 patients had NSTE-ACS with cTnI levels from 0.11 to 1.5 ng/mL (group 2), and 121 patients had NSTE-ACS with cTnI levels > 1.5 ng/mL (group 3). cTnI levels, clinical data, MACE, and in-hospital mortality were recorded prospectively. Logistic regression and receiver operating characteristic analyses were applied to determine prognostic cutoff values of cTnI.

RESULTS: Perioperative myocardial infarction was found in 5.8% of the patients in group 1, 8.3% of the patients in group 2 (odds ratio [OR], 1.5; 95% confidence interval [CI], 0.9 to 2.5), and 18.2% patients in group 3 (OR, 3.6; 95% CI, 2.1 to 6.2; p < 0.0001, Cochran-Armitage trend test). Low cardiac output syndrome occurred in 1.5% of patients in group 1, 4.2% of patients in group 2 (OR, 2.8; 95% CI, 1.3 to 6.1), and 10.9% patients in group 3 (OR, 6.5; 95% CI, 2.9 to 14.4; p < 0.0001). In-hospital mortality was 1.5% in group 1, 3.0% in group 2 (OR, 2.0; 95% CI, 0.8 to 4.8), but 6.6% in group 3 (OR, 4.6; 95% CI, 1.9 to 11.1; p < 0.0001). Univariate and multivariate logistic regression analyses identified cTnI as the strongest preoperative predictor for MACE and in-hospital mortality, respectively.

CONCLUSIONS: Preoperative cTnI measurement before CABG appears as a powerful and independent determinant of short-term surgical risk in patients with NSTE-ACS.