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 t horacic aorta, thoracoabdominal aorta, or aortic arch surgery, especially w hen surgery is performed using profound hypothermia and circulatory arrest (PHCA). Moreover, the diagnosis of non-Q-wave postoperative myocardial infa rction (PMI) is challenging because there is no gold standard. The aims of this study were to determine values for cardiac troponin I (cTnI) in patien ts 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 com plications in such patients. Design: Prospective, nonrandomized study. Setting: Single university hospital; Departments of Anesthesiology, Biochem istry and Vascular Surgery. Participants: Fifty-two consecutive patients were studied over a 2-year per iod. None was excluded, even patients who underwent emergency surgery. Interventions: Patients undergoing aortic arch or thoracoabdominal aortic s urgery with PHCA were studied. Thirty patients undergoing coronary artery b ypass grafting (CABG) in the same period constituted a control group. Measurements and Main Results: The cTnI concentrations were determined usin g an immunoenzymofluorometric assay on a Stratus analyzer (Dade, Massy, Fra nce) on blood samples obtained at recovery and on day 1 (D1) and D2. Sevent een patients developed a cardiac complication, which was lethal in 10 patie nts. In patients without cardiac complication, the peak level for cTnI was observed on D1. Cutoff values of cTnI were identical in both the CABG contr ol group (11.6 mu g/mL) and the sternotomy group (12.2 mu g/mL), but were s ignificantly greater (20.5 mu g/mL) in patients with a thoracotomy: approac h. Sensitivity and specificity of these cutoff values were high in both-gro ups (control group, sensitivity = 100%, specificity = 100%; sternotomy grou p, 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, vent s or fibrillation explains the increased cutoff value (12.2 mu g/mL). This value is similar to patients undergoing CABG surgery through a sternotomy a pproach 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 ca rdiac complications during the postoperative period. Copyright (C) 1999 by W.B. Saunders Company.