Preoperative Cardiac Troponin I to Assess Midterm Risks of Coronary Bypass Grafting Operations in Patients With Recent Myocardial Infarction

Background: The optimal timing for coronary artery bypass grafting (CABG) in patients with recent acute myocardial infarction (AMI) is unclear. Cardiac troponin I (cTnI) is a widely accepted biomarker of myocardial damage. The objective of this study was to determine whether preoperative cTnI values could be used to determine risk stratification for CABG operations in patients with recent AMI. Methods: Evaluated were 184 patients who sustained an AMI within 21 days of undergoing nonurgent CABG operations. They were divided into two groups according to their preoperative cTnI values: 117 patients with cTnI of 0.15 ng/mL or less and 67 with cTnI exceeding 0.15 ng/mL. Associations between study variables and events were assessed with logistic regression modelling. Time from AMI to operation was evaluated to define preoperative cTnI variation. Results: Values of cTnI tended to decrease when the interval between AMI and the operation increased. Preoperative cTnI values were significantly associated with a higher incidence of major postoperative complications (low cardiac output syndrome, intraaortic balloon pump necessity, mechanical ventilation >72 hours, acute renal failure, in-hospital mortality). Perioperative myocardial damage was more pronounced in patients with cTnI exceeding 0.15 ng/mL. Multivariate analyses revealed cTnI exceeding 0.15 ng/mL was an independent predictor for 6-month mortality (odds ratio, 3.7; p = 0.043). Conclusions: Preoperative cTnI exceeding 0.15 ng/mL in patients with recent AMI undergoing CABG is associated with higher postoperative myocardial damage and is a strong determinant of postoperative morbidity and mortality within the 6-month period.