Diagnostic performance and prognostic value of serum troponin T in suspected acute myocardial infarction

Ravkilde J, Herder M, Gerhardt W, Ljungdahl L, Pettersson T, Tryding N, Mailer B.H, Hamfelt A, Graven T, Åsberg A, Helin M, Penttilä I, Thygesen K. Diagnostic performance and prognostic value of serum troponin T in suspected acute myocardial infarction. Scand J Clin Lab Invest 1993; 53: 677-685.Cardiac troponin T (TnT) is a new serological marker for use as a diagnostic tool for myocardial damage. A blinded prospective multicentre study representing 298 patients suspected of having acute myocardial infarction (AMI), and admitted to the coronary care units of six Scandinavian Hospitals was undertaken to assess the diagnostic performance and prognostic efficacy of a new cardiospecific TnT immunoassay. We used a discriminator TnT value of 0.20μg 1−1. One hundred and fifty five patients (52%) had definite AMI, based on WHO criteria (all had peak S-TnT values of ≥ 0.20 μg 1−1); 127 patients (43%) had ischaemic heart disease (IHD) without AMI; and 16 patients (5%) had non-IHD (all had peak S-TnT values of <0.20μg 1−1). The 127 IHD-patients without definite AMI could be subdivided into a group of 44 patients with S-TnT peak values of < 0.20 μgl−1, and a group of 83 patients with TnT below this level. An equal identification of these patients among the centres was seen (mean ± SD 35 ± 13%; range 20-55%). A follow-up study was able to define the clinical significance of these findings. The cumulative 6 months probability of suffering cardiac death or AMI was significantly higher in the subgroup with increased TnT values (14% (6/44)) as compared to the other subgroup (4% (3/83)) (Log-rank test, p = 0.025). The probability of cardiac events was 15% for the patients with definite AMI. We conclude that increased troponin T in serum can detect a subgroup of IHD-patients in whom AMI has been ruled out, but who still have a prognosis as serious as patients with definite AMI.