Misdiagnosis of acute myocardial infarction.

A total of 979 cardiac profiles were reviewed. Seventeen cases were found to have elevated CK-BB by electrophoresis and were misidentified by the immunoinhibition/immunoprecipitation technique as elevated creatine phosphokinase (CK-MB). Eleven of the 17 cases also had elevated lactate dehydrogenase (LD) LD-5/LD-1 ratio; five cases were motor vehicle accident (MVA), four cases were prostatic carcinoma (PC), and one case each of breast carcinoma and coronary heart disease. One case of PC and one of MVA with a preliminary clinical diagnosis of acute myocardial infarction (AMI) were presented. Our findings underscore the importance of electrophoretic confirmation of the presence of CK-MB when detected by a quantitative technique. Clinicians should consider the possibilities of PC or other cancers when elevated "CK-MB" is present in conjunction with a raised LD-5/LD-1 ratio in patients who fail to show clear-cut clinical evidence of AMI. The mechanism of elevated CK-BB and LD-5/LD-1 ratio in PC patients are discussed.