Beyond CK-MB. Biochemical markers for perioperative myocardial infarction.

Diagnosis of perioperative myocardial infarction remains an important but challenging task. Both clinical symptoms and electrocardiographic changes have inherent limitations. Therefore, biochemical markers for myocardial injury are critical diagnostic tools. The use of creatine kinase isoenzymes (CK-MB) has enhanced detection of perioperative myocardial infarction; however, skeletal muscle damage during surgery limits CK-MB specificity. In this regard, the cardiac troponins appear to offer increased sensitivity, primarily because of their prolonged diagnostic window and even may offer enhanced specificity (especially troponin-I) in patients with surgical skeletal muscle damage. In addition, the convenience of relatively infrequent sampling (because of the prolonged diagnostic window), as well as potential cost savings, make use of the troponin markers attractive. However, definitive data in high-risk patients undergoing either cardiac or noncardiac surgery are still lacking, and significant questions remain regarding appropriate thresholds, specificity of troponin-T, and comparative accuracy of troponin-T, troponin-I, and CK-MB for diagnosis (and prognosis) of perioperative myocardial infarction.