Cardiac isoenzymes following heart transplantation.

Creatine phosphokinase (CPK) isoenzymes are commonly obtained after heart transplantation (HT) to assess myocardial injury of the donor heart. This investigation retrospectively evaluated the utility of this practice. Fifty-six recipients of orthotopic heart transplants had at least two daily CPK-MB studies following HT. All patients were followed up for at least one year (or until death). Nineteen patients had entirely negative CPK-MB determinations (NEG). Eighteen patients had a single positive CPK-MB determination, and were considered to be equivocal (EQUIV). Nineteen patients had more than one daily positive CPK-MB determination (POS). To evaluate the influence of positive CPK-MB determinations on the outcome of HT, we compared the results in the NEG and POS groups. There was no difference in the donor organ ischemic times between the two groups. The duration of follow-up for the two groups was also similar (1,192 days vs 1,020 days). The NEG and POS groups had no significant difference in: 1 year survival (84 percent vs 74 percent); freedom from treated rejection episodes in 3 months (39 percent vs 42 percent); and freedom from coronary artery disease (CAD) at 3 years (83 percent vs 86 percent). Additionally, the ejection fractions of the donor hearts were similar at 1 year post-transplant for the 2 groups (64 percent vs 59 percent). We conclude that myocardial injury, as reflected by post-transplant CPK-MB levels, does not predict one-year mortality, predisposition to rejection, predisposition to coronary artery disease, or ultimate graft dysfunction. In an effort to perform HT more economically, we no longer obtain CPK-MB levels following HT.