Importância da troponina I no diagnóstico do infarto do miocárdio no pós-operatório de cirurgia de revascularização

Objective: The aim of this study is to establish a cut-off value for troponin I by correlating it to occurrence of postoperative myocardial infarction. Methods: 180 consecutive patients with coronary disease referred for surgery were included. The mean age of the patients were 60.6 (+/- 9.3) years, with 119 (66.1%) males and 61 (33.9%) females. The patients were divided into two groups: group without myocardial infarction (A) 170 patients - and with myocardial infarction (B) 10 patients. The troponin I was collected from each patient at the beginning of anesthesia and on the second postoperative day by correlating it to presence or not of postoperative myocardial infarction. StatsDirect 1.6.0 for Windows was used for statistical analysis. Results: Preoperative troponin I was 1.0 (+/- 6) ng/ml as mean. Univariate logistic regression showed correlation of troponin I of the second postoperative day with myocardial infarction (P=0.0005). ROC curve was used to define the cutoff value, and 6.1 ng/ml (sensitivity=90.0%, specificity=82.1%, OR=49.8 with CI=95% 6.1-410.4, P<0.0001) were found. Conclusion: The chance of a patient with postoperative myocardial infarction to present troponin I equal to or higher than 6.1 ng/ml is 49.8-fold higher than the chance of a patient without infarction to present troponin I higher than this value.