CK-MB isoenzyme in patients with polymyositis.

Total serum creatine kinase and isoenzyme levels were studied in five patients with polymyositis. In all five patients, CK-MB isoenzyme was demonstrated by the column chromatography and electrophoretic method, although there was no evidence of myocardial infarction. The persistent elevation of CK-MB in patients with polymyositis is in contrast to the usual transient increase in myocardial infarction. Serial CK-MB isoenzyme quantitation can be used to distinguish myocardial infarction from polymyositis. CK-MB is a more sensitive indicator than AST and LDH as a monitoring device, but offers no advantage over total CK activity.