The prognostic significance of serial myoglobin, troponin I, and creatine kinase-MB measurements in patients evaluated in the emergency department for acute coronary syndrome.

STUDY OBJECTIVE: We sought to determine the value of serial measurements of myoglobin, cardiac troponin I (cTnI), and creatine kinase-MB (CK-MB) to predict 30-day adverse events in patients evaluated in the emergency department (ED) for possible acute coronary syndrome.

METHODS: Serum myoglobin, cTnI, and CK-MB levels were measured at presentation, 90 minutes, 3 hours, and 9 hours in patients evaluated in the ED for possible acute coronary syndrome. In 764 consecutive patients, the ability of each individual marker and combination of markers to predict a 30-day adverse event (death or myocardial infarction) over time was calculated.

RESULTS: There were 109 (14%) patients with an adverse event at 30 days (84 myocardial infarctions and 43 deaths). The sensitivities of initial measurements of myoglobin, cTnI, and CK-MB for identifying adverse events were 60%, 47%, and 52%, respectively. The combined sensitivity of myoglobin and cTnI measurements during a 9-hour period was 94%; specificity was 50%. Measurement of CK-MB did not improve sensitivity.

CONCLUSION: The measurement of both myoglobin and cTnI during a 9-hour period was the most predictive of subsequent adverse events in patients evaluated in the ED for possible acute coronary syndrome.