Cardiac troponin I cutoff values to predict postoperative cardiac complications after circulatory arrest and profound hypothermia

Objective: Cardiac failure and myocardial infarction are complications of thoracic aorta, thoracoabdominal aorta, or aortic arch surgery, especially when surgery is performed using profound hypothermia and circulatory arrest (PHCA). Moreover, the diagnosis of non-Q-wave postoperative myocardial infarction (PMI) is challenging because there is no gold standard. The aims of this study were to determine values for cardiac troponin I (cTnI) in patients undergoing aortic arch or thoracoabdominal aortic surgery with PHCA who were free of cardiac complications in the postoperative period, and to test the validity of cutoff values of cTnI to predict postoperative cardiac complications in such patients. Design: Prospective, nonrandomized study. Setting: Single university hospital; Departments of Anesthesiology, Biochemistry and Vascular Surgery. Participants: Fifty-two consecutive patients were studied over a 2-year period. None was excluded, even patients who underwent emergency surgery. Interventions: Patients undergoing aortic arch or thoracoabdominal aortic surgery with PHCA were studied. Thirty patients undergoing coronary artery bypass grafting (CABG) in the same period constituted a control group. Measurements and Main Results: The cTnI concentrations were determined using an immunoenzymofluorometric assay on a Stratus analyzer (Dade, Massy, France) on blood samples obtained at recovery and on day 1 (D1) and D2. Seventeen patients developed a cardiac complication, which was lethal in 10 patients. In patients without cardiac complication, the peak level for cTnI was observed on D1. Cutoff values of cTnI were identical in both the CABG control group (11.6 mu g/mL) and the sternotomy group (12.2 mu g/mL), but were significantly greater (20.5 mu g/mL) in patients with a thoracotomy: approach. Sensitivity and specificity of these cutoff values were high in both-groups (control group, sensitivity = 100%, specificity = 100%; sternotomy group, sensitivity = 78%, specificity = 100%; thoracotomy group, sensitivity = 100%, specificity = 94%). Conclusion: In patients who underwent surgery using PHCA for aortic arch or descending aorta repair, myocardial damage related to cardiac arrest, vents or fibrillation explains the increased cutoff value (12.2 mu g/mL). This value is similar to patients undergoing CABG surgery through a sternotomy approach with cardioplegia administration. In contrast, and probably related to the absence of cardioplegia, patients undergoing surgery through a left thoracotomy approach had a greater cutoff value (20.5 mu g/mL). Values of cTnI greater than these respective cutoff values were closely related to cardiac complications during the postoperative period. Copyright (C) 1999 by W.B. Saunders Company.