The level of cardiac specific troponin (cTn) may be important in patients with acute coronary syndrome (ACS), but with normal electrocardiography (ECG).

Three hundred and nineteen patients (61±11 years, M:F=212:107), with ACS and normal ECG, who underwent a diagnostic coronary angiogram (CAG), between July 2000 and June 2001, were analyzed according to their cTn level. The clinical characteristics, initial CAG findings and major adverse cardiac events (MACE), during a one-year clinical follow-up, were compared between positive and negative cTn groups.

Of the enrolled patients, 191 had a negative cTn (group A, 61±10 years, M:F=131:60), and 128 a positive cTn (group B, 60±11 years, M:F=81:47), and 176 (55.2%) were shown to have significant coronary artery stenosis on CAG. There were no significant differences in risk factors between the two groups. The mean left ventricular ejection fraction was 64±9%, and was lower in group B than in group A (59±10% vs. 67±7%, p<0.05). cTn positivity was associated with the percentage of significant coronary artery stenosis present (88% vs. 32%, p<0.05), a smaller minimal luminal diameter (1.09±0.44 mm vs. 2.68±0.33 mm, p<0.05) and a larger diameter of stenosis (68±6% vs. 44±6%, p<0.05). A multi-vessel lesion was more common in group B than in group A (58.3% vs. 30.3%, p<0.05). During the one-year follow-up period, 36 patients developed MACE, resulting in 3 deaths, 7 acute myocardial infarctions and 34 patients with restenosis. MACE was observed in 9 patients of group A and in 27 of group B (4.7% vs. 21.1%, p<0.05).

The troponin levels are valuable for the early diagnosis, and prediction of the long-term prognosis, in patients with ACS and a normal ECG.