Intermittent cardiac troponin-I screening is an effective means of surveillance for a perioperative myocardial infarction

Objective: Several studies suggest that cardiac troponin-I (cTn-I) is a more sensitive indicator of cardiac injury compared with other biochemical markers of injury, but the strategy with the highest diagnostic yield (true positive and true negative) for perioperative surveillance is unknown. The authors undertook a prospective evaluation of the perioperative incidence of myocardial infarction (MI) and evaluated surveillance strategies for the diagnosis of MI. Design: Prospective, cohort study. Setting: Two university hospitals. Participants: Four hundred sixty-seven high-risk patients requiring noncardiac surgery. Interventions: None. Measurements and Main Results: The diagnosis of myocardial injury was determined by cardiac protein markers combined with either postoperative changes on 12-lead electrocardiography or 1 of 3 clinical symptoms consistent with MI (chest pain, dyspnea, requirement for hemodynamic support). A receiver operating characteristic curve evaluating troponin in the diagnosis of MI revealed a value of 2.6 ng/mL as having the highest sensitivity and specificity. The sensitivity and specificity of cTn-I value >= 2.6 ng/mL, troponin >= 1.5 ng/mL, total creatine kinase (CK) >= 170 IU/L with MB >= 5%, and CK-MB >= 8 ng/mL were compared. Surveillance strategies were determined on a subset of patients (n = 257). The incidence of MI was 9.0% by cTn-I >= 2.6 ng/mL criteria, 19% by cTn-I >= 1.5 ng/mL, 13% by CK-MB mass, and 2.8% by CK-M13%. The specificity of cTn-I >= 2.6 ng/mL as an indicator of MI was 98%, and its positive predictive value (PPV) was 85%. Cardiac troponin-I >= 2.6 ng/mL had equal specificity but greater PPV than the cTn-I : 1.5 ng/mL (specificity 98% and PPV 79%). If surveillance of cTn-I >= 2.6 ng/mL was used to detect MI, then the strategy with the highest diagnostic yield was surveillance on postoperative days 1, 2, and 3. Conclusions: Perioperative cardiac injury continues to occur frequently after noncardiac surgery, as detected by cTn-I. Serial monitoring of cardiac troponin-I on postoperative days 1, 2, and 3 provides the strategy with the highest diagnostic yield for surveillance of MI. (c) 2005 Elsevier Inc. All rights reserved.