Cardiac contusion and creatine kinase-MB: a pertinent case history and brief review of the utility of CK-MB.

Cardiac contusion is defined as the myocardial cellular damage that can result from nonpenetrating chest trauma. However the noninvasive diagnosis of this lesion is problematic. Among the criteria suggested for the diagnosis of cardiac contusion is an elevation of serum levels of the heart-specific isoform of the enzyme creatine kinase (CK-MB). We present here the case of a patient who, on the basis of an initial elevation of CK-MB, was suspected of having cardiac contusion as a result of a motor vehicle accident. The patient was clinically stable and there were no other signs to support this diagnosis. Serial analyses showed a fall in total CK to below the upper limit of the reference interval but, as a percent of total activity, CK-MB was constantly slightly elevated (values 5.1-6.5%, upper limit of normal = 4%). At the same time the patient appeared to be improving clinically. The patient's status deteriorated suddenly and he eventually went to surgery where a large intramural haematoma and a left ventricular aneurysm were discovered. The significance of the elevations of serum CK-MB is discussed and a brief review of the literature is presented.