BACKGROUND: The impact and prognostic value of the redefinition of myocardial infarction (MI) with more sensitive markers have not been evaluated prospectively in a large, less selected population with acute coronary syndrome (ACS).

METHODS: We evaluated the attack and case-fatality rates of MI based on initial and/or peak creatine kinase (CK), creatine kinase-MB (CK-MB), and cardiac troponin (the upper limit of normal [ULN] was defined according to the local hospital's standard) in a prospective observational registry of 26,267 patients with ACS admitted to 106 hospitals in 14 countries.

RESULTS: The addition of cardiac troponin-positive status to CK status as a criterion for the diagnosis of MI resulted in as many as 1 in 4 additional patients meeting the redefined criteria. Compared with patients without elevated levels of CK and cardiac troponin, the crude odds for dying during hospitalization were significantly higher for patients with elevated troponin but not CK levels of greater than or equal to the ULN (odds ratio [OR] 2.2, 95% CI 1.6-2.9), those without CK levels >2 times the ULN (OR 2.8, 95% CI 2.2-3.5), and those with nonelevated levels of CK-MB (OR 2.1, 95% CI 1.4-3.2). The addition of cardiac troponin-positive status significantly increased the multivariable-adjusted odds for hospital death in patients with CK < or =2 times the ULN (OR 1.6, 95% CI 1.2-2.1) but not for patients without elevated levels of CK or CK-MB.

CONCLUSIONS: The prognostic value of cardiac troponin, beyond that supplied by CK status or important baseline characteristics, assists in the identification of patients with ACS who are at increased risk for death.