SHAHEED RAJAIE CARDIOVASCULAR MEDICAL CENTER, TEHAN IRAN
Background: One of the most common causes of hospital admissions is chest pain of ischemic origin; a number of such cases tend to be diagnosed as acute myocardial infarction (MI) and sent to CCUs. Earlier diagnosis in these patients, particularly in those without typical signs of MI, results in better and faster service to the patient and, therefore, reduces the rate of mortality. The special role of cardiac enzymes in diagnosing myocardial infarction has been known for a long time. This study sought to investigate the sensitivity and specificity of myoglobin in MI diagnoses. As regards the role of inflammatory factors in MI, the relationship of C-reactive protein (CRP) and MI was also investigated.
Methods: Seventy-eight patients presenting to our emergency department with acute chest pain were interviewed. After it had been confirmed that they fulfilled the inclusion criteria, samples were collected for measurement of myoglobin, CRP and CK-MB. The measurement was repeated after six hours.
Results: All the patients who were diagnosed as having myocardial infarction had myoglobin levels higher than normal, which demonstrated 100% sensitivity and NPV of this test for the diagnosis of acute MI (AMI). However, the plasma level of myoglobin was also higher than normal in about 20% of the non-MI patients, which showed that the specificity of this test was about 78% and the accuracy of the test was 87%. The CRP level was also higher in MI patients in comparison to non-MI patients.
Conclusion: The results of this study and similar studies demonstrated that myoglobin measurement for the patients referred to the emergency ward should be taken at least twice, i.e. once upon admission and then after six hours. Furthermore, CRP evaluation on the first day can result in better and faster diagnoses of such patients.