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Ruling out myocardial infarction with troponin T and creatine kinase MB mass: diagnostic and prognostic aspects
H Koukkunen1, K Penttilä, A Kemppainen
1Department of Medicine, Kuopio University Hospital, Finland.
Objective:
To investigate the time window for ruling out myocardial infarction (MI) with troponin T (TnT) and creatine kinase isoenzyme MB mass (CK-MBm) and the prognosis of patients with ruled-out MI diagnosis.
Design:
The study was based on 397 patients admitted with a suspected acute coronary syndrome but with relief of symptoms within 24 h.
Results:
MI diagnosis was confirmed with elevated TnT (>0.10 microg/l) in 108 patients. in 91% within 12-24 h from the onset of symptoms, and in 99% within 12 h from admission. In 94 of these patients CK-MBm became elevated (>5.0 microg/l). in 95% within 10-12 h from the onset of symptoms, and in 99% within 6 h from admission. Among patients with ruled-out MI diagnosis, the 1-year incidence of recurrent coronary events was 29% in those with positive history of coronary heart disease (CHD) but only 7% in those without prior CHD (p < 0.001).
Conclusion:
Using TnT or CK-MBm, MI can be ruled out within 12 h from admission in the majority of patients. Among patients with ruled-out MI diagnosis, positive history of CHD is an important determinant of prognosis.