Changes in plasma myoglobin levels in ischemic heart disease

: The aim of the present study is to evaluate the real need and the sensitivity of serum myoglobin levels as an early index for the diagnosis of acute myocardial infarction. A total of 62 patients (38 suffering from acute myocardial infarction, 16 from "angina pectoris", 8 from heart failure) and 20 healthy volunteers were included in the study. The patients with acute myocardial infarction were divided in 3 subgroups according to the time passed between the beginning of the pain and their admittance to our Department (Coronary Care Unit), that was, less than 6 hours, between 6 and 12 hours, between 12 and 24 hours. Among the patients with "angina", 8 presented spontaneous crisis whereas 4 had crisis only during treadmill test. 8 of the healthy volunteers received intramuscular injections of physiological solution every 12 hours during the 3 days preceding the study. In all subjects serum myoglobin level were measured by radioimmunoassay; in patients with acute myocardial infarction serum CK and MBCK levels with enzymatic method were measured too. No variation of plasma myoglobin levels was seen in patients with angina, neither in healthy volunteers had they received or not intramuscular injections. The low increase in plasma myoglobin levels observed in patients with heart failure might be due to a deficit of renal function. Serum myoglobin levels were significantly elevated in all the patients with acute myocardial infarction, whereas plasma CK and MBCK levels were significantly high only 6 hours after the necrosis. In myocardial infarction the levels of myoglobin rise during the first hours, peak at 10 hours and return to normal in 20 hours.(ABSTRACT TRUNCATED AT 250 WORDS)