Serum creatine kinase and lactate dehydrogenase isoenzyme levels in patients after major esophageal surgery, esophageal dilation, and acute myocardial infarction.

All three isoenzymes of creatine kinase (CK), including MB, the fraction used in diagnosing acute myocardial infarction (AMI), have been found in the esophagus. Clinical reports suggest that injuries to the esophagus can cause changes in peripheral serum CK. This prospective study was designed to delineate whether esophageal dilation or major esophageal surgery would cause changes in serum CK and lactate dehydrogenase isoenzymes that might be consistent with the diagnosis of an AMI. Two groups of patients admitted to a coronary care unit were used as controls: patients with electrocardiographically proved AMI and those who had chest pain but who had AMI ruled out by sequential electrocardiograms. The coronary care unit patients had serum enzymes determined on admission, then every 8 hours for four samples, and then daily for 3 days. The surgical patients had determinations preoperatively, in recovery, every 8 hours for four samples, and daily for 5 days. The patients who had esophageal dilations had serum enzyme levels drawn before the procedure and every 8 hours for 2 days after dilation. Serum total CK and lactate dehydrogenase levels were determined by automated spectrophotometry. Isoenzyme levels were determined by agarose gel electrophoresis. The data suggest that small serum CK-MB bands that may be generated by esophageal surgery or dilation can be differentiated from those seen in AMI and that AMI can be confirmed by simultaneous analysis of serum lactate dehydrogenase isoenzymes.