Myoglobin as an early indicator of acute myocardial infarction.

The ECG and the determination of serum enzymes creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) may be falsely normal early in acute myocardial infarction. Myoglobin, an oxygen-carrying protein found in cardiac muscle and striated skeletal muscle, presents an attractive alternative to CPK and LDH in the emergency department setting for identification of acute myocardial infarction. Myoglobin levels may be elevated in the serum within one hour after myocardial cell death with peak levels reached within four to six hours. We report a study of 59 patients presenting to a community hospital with chest pain and subsequent hospitalization. Twenty-one had an acute myocardial infarction. Presenting (0 hour) myoglobin determination was positive in 13 of 21 individuals, while CPK-MB was positive in only three. Serum myoglobin elevation at three hours identified all 21 patients with myocardial infarction with the CPK-MB determination positive in 19. Serum myoglobin elevation may permit early identification of myocardial infarction, with subsequent verification using CPK-MB determination, allowing appropriate intensive care admission for careful monitoring of these patients.