Diagnostic and prognostic significance of minimally elevated creatine kinase-MB in suspected acute myocardial infarction.

CK-MB changes were studied using agarose gel electrophoresis in 244 patients admitted to a coronary care unit for suspected acute myocardial infarction (AMI). A range of minimally elevated CK-MB levels, from 1 to 24 IU/liter, was identified as representing uncertain AMI events. Positive AMI events were defined by elevations of 25 IU/liter or more documented in patients with new Q waves or abnormalities in all enzyme and isoenzyme levels. Negative AMI events were defined by elevation of 0 IU/liter, observed in all control subjects. The 1-year cardiac mortality rates in the "positive"-AMI (n = 91) and "uncertain"-AMI (n = 22) groups were identical (22%), and significantly higher than that in the "negative"-AMI group (n = 93) (6%) (p less than 0.05). However, when a larger uncertain-AMI group of 115 patients was compiled by 2 collaborating centers, the 1-year cardiac mortality rate in the 39 patients with chest pain alone was 0%, vs 33% in the 76 patients with accompanying severe medical problems such as cardiac or respiratory failure. Whether minimal CK-MB elevations represent AMI of limited extent is not clear. These elevations occur most often in association with severe medical problems, and in patients without such problems, they may not indicate a poor prognosis.

Duke Scholars

Author Robert M. Califf Medicine, Cardiology