Deagnostic Value of Myoglobin in Early Diagnosis of Acute Myocardial Infarction

ABSTRACT

BACKGROUND: Exact and early diagnosis of acute myocardial infarction (AMI) is essential for the subsequent routine management of this frequent cardiovascular disease. Currently, AMI has been diagnosed using the combination of the history, electrocardiogram(ECG), and biochemical markers of myocardial necrosis. At present, many biochemical markers are used to diagnose AMI. In this study, the predictive values of serum myoglobin and creatine kinase-MB (CK-MB) were compared in the emergency department. METHODS: Fifty-four consecutive patients who presented within 12 hours from onset of chest pain of presumed cardiac origin were enrolled into the study. Patients with trauma or renal failure were excluded. The serial serum myoglobin and CK-MB levels were obtained prospectively at admission and 2, 4, 6, 12, 24 and 48 hours after admission. We compare the levels of serum myoglobin and CK-MB within 2, 4, 6, 8, 10, 12, 24, and 48 hours after symptom onset respectively. And we compare the sensitivity, specificity, positive predictive value, and negative predictive value of myoglobin and CK-MB. RESULTS: Using World Health Organization criteria, 28 AMI patients were identified. Mean time from symptom onset to presentation was 4.1+/-1.3 hours. the predictive values of serum myoglobin were better than those of CK-MB within 6 hours after symptom onset. But, 6 hours after symptom onset, the predictive values of CK-MB were better than those of serum myoglobin. The false positive cases of serum myoglobin were 3-one was lung cancer with pleural effusion and the others were unstable angina. The false positive cases of CK-MB were 6-one case was viral myocarditis and the ohters were unstable angina. CONCLUSION: To compare the serum myoglobin and CK-MB in the diagnosis of AMI, serum myoglobin had better predictive values than CK-MB within 6 hours after symptom onset and useful in the early diagnosis of AMI. But, 6 hours after symptom onset, CK-MB had better predictive values than serum myoglobin and useful in following up.