[Utility of the serum biochemical markers CPK, CPK MB mass, myoglobin, and cardiac troponin T in a chest pain unit. Which marker determinations should be requested and when?].

BACKGROUND The prognostic value of biochemical markers in relation to time since onset of chest pain was evaluated in an emergency room with a chest pain unit. METHODS In a single-center, prospective study we included 321 consecutive patients admitted to the emergency room with suspected unstable angina IIIB and an evolution of less than 12 hours. Blood samples were collected for CPK, CPK MB mass, myoglobin, and cardiac troponin T assays 6, 12, and 18 h after the onset of pain. ROC curve analysis was carried out to compare biochemical markers in terms of cutoff values and time since onset of pain. We determined the relation between prognosis and biochemical markers before and after adjustment for baseline characteristics. RESULTS CPK mass and myoglobin showed the maximum sensitivity and specificity for new ischemic recurrences 6 hours after the onset of chest pain with laboratory cutoff values. We had to wait 12 h after the onset of pain for troponin T to be useful using the laboratory cutoff value (0.1 ng/ml). A single determination 6 hours after onset of chest pain of cardiac troponin T above 0.04 ng/ml was the most sensitive and specific marker for new ischemic recurrences. CONCLUSIONS A single blood determination of cardiac troponin T 6 hours after the onset of chest pain complete the prognostic stratification in combination with clinical and ECG variables. The best cutoff point of cardiac troponin T, based on univariate and multivariate analysis, was 0.04 ng/ml 6 h after the onset of chest pain.