The prognostic value of serum troponin T in unstable angina.

BACKGROUND

Cardiac troponin T is a regulatory contractile protein not normally found in blood. Its detection in the circulation has been shown to be a sensitive and specific marker for myocardial cell damage. We used a newly developed enzyme immunoassay for troponin T to determine whether its presence in the serum of patients with unstable angina was a prognostic indicator.

METHODS

We screened 72 patients with unstable angina (Class III, acute unstable angina) for serum creatine kinase activity, creatine kinase myocardial band (isoenzyme M) activity, and troponin T, every 8 h for 2 days after admission to the hospital. The outcomes of interest during the hospitalization were death and myocardial infarction.

RESULTS

Troponin T was detected in the serum of 24 of the 72 patients (34%) with acute angina at rest. Only four of these patients had elevated creatine kinase M activity. Of the 24 patients who were positive for troponin T, 12 had myocardial infarction, and 6 of these died during hospitalization. In contrast, only 2 of the 48 patients with angina at rest who were negative for troponin T had an acute myocardial infarction, and these patients died. Thus, 12 of the 14 patients with myocardial infarctions had detectable levels of troponin T; only 2 had elevated creatine kinase M activity.

CONCLUSIONS

Cardiac troponin T in serum appears to be a more sensitive indicator of myocardial-cell injury than serum creatine kinase MB activity, and its detection in the circulation may be a useful prognostic indicator in patients with unstable angina.