The value of troponin T in the coronary care unit.

OBJECTIVE: To assess the value of troponin T (TpT) in the coronary care unit (CCU) setting compared to creatinine phosphokinase (CK-MB) in patients admitted with acute coronary syndrome.

METHODS: This was a prospective study conducted over a period of 2 months between May 2003 and June 2003. All patients who were admitted to the CCU at Queen Alia Heart Institute, Amman, Jordan with acute coronary syndrome were included. Troponin T and CK-MB were performed simultaneously on all patients upon admission and serially every 4 hours for 24 hours. The times of the serial measurements from the onset of chest pain and the results were recorded. The result of coronary angiography was recorded in those patients who underwent this procedure during the index hospitalization. Patients with chest pain more than 48 hours prior to admission and those with renal impairment were excluded.

RESULTS: One hundred and ninety-seven patients were enrolled in our study. Sixty-one percent were males. The mean age was 60 years with a range of 28-90 years. The total number of patients with a positive biomarker (TpT or CK-MB) was 136. Forty-nine patients (36%) had a positive TpT without an accompanying CK-MB leak. Only 2 patients (1.4%) had a CK-MB without a positive TpT. The positive predictive value of TpT was 94%, with a negative predictive value of 96%, giving 98.5% sensitivity and 97% specificity. The earliest time from the onset of pain to having a positive TpT was one hour. Out of the 197 patients 173 (87.8%) had cardiac catheterization and it did not seem to have been affected by a negative TpT or CK-MB. There were 5 deaths, and their TpT results were well above the average positive value.

CONCLUSION: Troponin T is a more sensitive and specific biomarker than CK-MB in detecting myocardial injury. It can become positive as early as one hour from the onset of chest pain. The decision whether to do coronary angiography remains based on clinical assessment rather than laboratory data.