The MB fraction of creatine phosphokinase. An indicator of myocardial involvement in acute pericarditis.

An elevated level of the MB fraction of creatine phosphokinase (CPK) with normal serum myoglobin and normal CPK values was found in a case of acute idiopathic pericarditis. The elevated serum CPK-MB isozyme is suggested to be an indicator of myocardial involvement accompanying acute pericarditis. The normal CPK and serum myoglobin values and the pattern of rapid decrease of CPK-MB level ruled out the possibility of acute myocardial infarction.