Postoperative elevation of creatine kinase (CK-MB): does it contribute to diagnosis of myocardial infarction?

Purpose: This retrospective study sought to determine the benefit of measurement of changes in plasma creatine kinase - myocardial band (CK-MB) levels in elective postoperative high risk surgical patients beyond that obtained from the surface 12 lead ECG. Methods: The charts of 111 patients admitted to the surgical intensive care unit (SICU) of a tertiary level university teaching hospital were reviewed. They were screened using predetermined definitions of myocardial infarction (MI) (as reflected by changes in the 12 lead surface ECG (Minnesota code) or elevations in CK-MB) for complications such as pulmonary oedema, congestive heart failure, arrhythmias, or cardiogenic shock. Four groups were identified based on changes in the ECG indicative of MI (Present - ECG+ or Absent - ECG-) and elevations of CK-MB (Present - CKMB+ or Absent - CKMB-) and compared for the incidence of complications. Results: No patient with ECG- findings had a complication, Fifteen patients with ECG+ findings were identified and all had complications. Fourteen of these patients had CKMB+ results. In contrast, 29 patients with CKMB+ results alone (i.e., ECG-) had no complications. Conclusion: Clinically important (i.e., requiring therapeutic intervention) postoperative myocardial infarction was detected by ECG changes. The benefit of determining changes in CK-MB was minimal from a therapeutic perspective.