[The diagnosis of perioperative myocardial infarction in heart surgery]

Fifty three consecutive patients undergoing open heart surgery were prospectively studied to assess current techniques for diagnosing perioperative myocardial infarction (PMI). All patients had preoperative and postoperative electrocardiograms, serial determinations of serum creatine phosphokinase (CK), myocardial fraction of CK (CK-MB) and scintigraphy with technetium-99m labeled pyrophosphate. Seven patients (13.2%) sustained perioperative myocardial infarction. Four of these patients exhibited abnormal Q waves, and one poor R wave progression. Three of them had a positive scintigram. Two patients with a non-Q-wave infarction had a abnormal radioisotopic imaging. The CK and CK-MB were higher in patients with infarction (818.1 U) than in those without this complication (349 U) p less than 0.05. The relative sensitivity and relative specificity of given variables in the diagnosis of PMI were as follows: electrocardiogram 71.4% and 97.5% respectively; scintigraphy 71.4% and 94.1%; and serum enzymes 100% and 71.8%. Age, incidence of prior myocardial infarction, unstable angina, elevated left ventricular filling pressure, number of diseased coronary arteries, and number of grafts per patient did not correlate with PMI. Duration of extracorporeal circulation and number of electric shocks during surgery were slightly higher in the infarction group, but the difference was not significant. These results indicate that the combination of these three diagnostic procedures is the best way to evaluate myocardial damage after open heart surgery.