Utility of troponin I in patients with cocaine-associated chest pain.

UNLABELLED: Baseline electrocardiogram abnormalities and market elevations not associated with myocardial necrosis make accurate diagnosis of myocardial infarction (MI) difficult in patients with cocaine-associated chest pain. Troponin sampling may offer greater diagnostic utility in these patients.

OBJECTIVE

To assess outcomes based on troponin positivity in patients with cocaine chest pain admitted for exclusion of MI.

METHODS

Outcomes were examined in patients admitted for possible MI after cocaine use. All patients underwent a rapid rule-in protocol that included serial sampling of creatine kinase (CK), CK-MB, and cardiac troponin I (cTnI) over eight hours. Outcomes included CK-MB MI (CK-MB >or= 8 ng/mL with a relative index [(CK-MB x 100)/total CK] >or= 4, cardiac death, and significant coronary disease (>or=50%).

RESULTS

Of the 246 admitted patients, 34 (14%) met CK-MB criteria for MI and 38 (16%) had cTnI elevations. Angiography was performed in 29 of 38 patients who were cTnI-positive, with significant disease present in 25 (86%). Three of the four patients without significant disease who had cTnI elevations met CK-MB criteria for MI, and the other had a peak CK-MB level of 13 ng/mL. Sensitivities, specificities, and positive and negative likelihood ratios for predicting cardiac death or significant disease were high for both CK-MB MI and cTnI and were not significantly different.

CONCLUSIONS

Most patients with cTnI elevations meet CK-MB criteria for MI, as well as have a high incidence of underlying significant disease. Troponin appears to have an equivalent diagnostic accuracy compared with CK-MB for diagnosing necrosis in patients with cocaine-associated chest pain and suspected MI.