Association between minor elevations of creatine kinase-MB level and mortality in patients with acute coronary syndromes without ST-segment elevation

Context Controversy surrounds the diagnostic and prognostic importance of s lightly elevated cardiac markers in patients with acute coronary syndromes without ST-segment elevation. Objectives To investigate the relationship between peak creatine kinase (CK )-MB level and outcome and to determine whether a threshold CK-MB level exi sts below which risk is not increased. Design and Setting Retrospective observational analysis of data from the in ternational Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Sup pression Using Integrilin Therapy (PURSUIT) trial, conducted from November 1995 to January 1997, Patients A total of 8250 patients with acute coronary sydromes without ST-s egment elevation who had at least 1 CK-MB sample collected during their ind ex hospitalization. Main Outcome Measure Mortality at 30 days and 6 months, was assessed by cat egory of index-hospitalization peak CK-MB level (0-1, >1-2, >2-3, >3-5, >5- 10, or >10 times the upper limit of normal). Multivariable logistic regress ion was used to determine the independent prognostic significance of peak C K-MB level after adjustment for baseline predictors of 30-day and 6-month m ortality. Results Mortality at 30 days and 6 months increased from 1.8% and 4.0%, res pectively, in patients with normal peak CK-MB levels, to 3.3% and 6.2% at p eak CK-MB levels 1 to 2 times normal, to 5.1% and 7.5% at peak CK-MB levels 3 to 5 times normal, and to 8.3% and 11.0% at peak CK-MB levels greater th an 10 times normal. Log-transformed peak CK-MB levels were predictive of ad justed 30-day and 6-month mortality (P<.001 for both). Conclusions Our data show that elevation of CK-MB level is strongly related to mortality in patients with acute coronary syndromes without ST-segment elevation, and that the increased risk begins with CK-MB levels just above normal. in the appropriate clinical context, even minor CK-MB elevations sh ould be considered indicative of myocardial infarction.