The objective of this study was to determine the combined accuracy of emergency department (ED) cardiac enzymes and electrocardiograms (ECGs) in patients who were admitted to "rule-out" myocardial infarction (ROMI). A retrospective analysis of ED creatinine kinase (CK), CKMB, and ECG was performed and the results were compared with final hospital diagnosis of MI, in the ED of a medical school- and university hospital-affiliated teaching Veterans Affairs Medical Center. Approximately 222 consecutive ED patients admitted to ROMI, including 43 (19%) MI patients, 29 (67%) of whom presented to the ED within 24 hours of symptom onset were eligible to participate. Interventions included an analysis of CK and CKMB results and ECG findings. There were no statistical differences in the sensitivities, specificities, and predictive values when the two cardiac enzymes were compared. Almost all of the elevated cardiac enzyme results occurred in MI patients who presented within 24 hours of symptom onset, more than half of whom had ED cardiac enzyme elevations. For all MI patients, regardless of duration of symptoms, more than half of the ED ECGs had new ST-T changes consistent with an acute MI or acute myocardial ischemia. In the MI patients who presented within 24 hours of symptom onset, 79% had positive enzymes or ECG or both in the ED. No statistically significant difference in the sensitivity rates for MI between the CK and CKMB comparing enzymes with ECGs was found.(ABSTRACT TRUNCATED AT 250 WORDS)