Value of creatine phosphokinase isoenzyme determinations in the diagnosis of myocardial contusion.

Myocardial contusion is an injury often missed in the patient with severe multisystem trauma. Fifty patients with physical findings or mechanisms of injury that were suggestive of possible nonpenetrating injury to the heart were studied with serial creatine phosphokinase isoenzyme (CPK/MB), continuous arrhythmia monitoring, and ECGs for at least 72 hours. Two-dimensional echocardiograms were obtained on all patients within 48 hours of admission. Seventy-two percent (36 of 50) had detectable CPK/MB. Ten patients had echocardiograms suggestive of cardiac contusion. Of these ten, three had no detectable CPK/MB and six had CPK/MB of less than 5%. CPK/MB had a sensitivity of 70% and a specificity of 27.5%. We conclude that in the patient with multisystem injury, CPK/MB determinations are not reliable. The decision to evaluate the patient with echocardiography should be made on the basis of physical findings and, more importantly, on mechanism of injury.