Is it Necessary to Study both Creatine Kinase MB and Troponin for an Acute Diagnosis of Myocardial Infarction?

ABSTRACT

PURPOSE: Cardiac enzymes such as creatine kinase MB (CK-MB) and troponin-T, are useful tools for diagnosing acute myocardial infarction (AMI). However, the cost of assessing cardiac enzymes is not inexpensive. So, this study was performed to learn the necessity of both cardiac enzyme tests to confirm AMI. METHODS:One hundred thirty three patients with AMI visited our emergency center from July 2006 to June 2008. We excluded 39 patients who arrived at the emergency center 24 hours or more after chest pain had begun. We did a retrospective study. We checked cardiac enzymes at about 3, 6, 12 and 24 h after chest pain began. Then, we compared CK-MB and troponin-T values to determine their elevation time after chest pain. RESULTS: The elevation time of CK-MB and troponin-T after chest pain was not related to age, sex, high risk factors such as hypertension and diabetes, or ST segment elevation. We found that CK-MB and troponin-T at about 6 h after chest pain were significantly higher than at 3 h (p<0.05 for both). However, the numerical value for CK-MB became elevated above the normal range faster than the value for troponin-T (67.2% vs. 59.7%, respectively at about 6 h after chest pain onset). CONCLUSION: Although, troponin has been known as a more specific marker than CK-MB, CK-MB increased faster than troponin-T after chest pain began. To diagnose AMI as soon as possible, the measurement of CK-MB appears to be more useful than troponin-T. Serial checks of CK-MB is important.