Cardiac troponin T in chest pain unit patients without ischemic electrocardiographic changes: angiographic correlates and long-term clinical outcomes

OBJECTIVES We prospectively evaluated the relation between cardiac troponin T (cTnT) level, the presence and severity of coronary artery disease (CAD) and long-term prognosis in patients with chest pain but no ischemic electrocardiographic (ECG) changes who had short-term observation. BACKGROUND Cardiac TnT is a powerful predictor of future myocardial infarction (MI) and death in patients with ECG evidence of an acute coronary syndrome. However, for patients with chest pain with normal ECGs, it has not been determined whether cTnT elevation is predictive of CAD and a poor long-term prognosis. METHODS In 414 consecutive patients with no ischemic ECG changes who were triaged to a chest pain unit, cTnT and creatine kinase, MB fraction (CK-MB) were evaluated ≥10 h after symptom onset. Patients with adverse cardiac events, including death, MI, unstable angina and heart failure were followed for as long as one year. RESULTS A positive (>0.1 ng/ml) cTnT test was detected in 37 patients (8.9%). Coronary artery disease was found in 90% of 30 cTnT-positive patients versus 23% of 144 cTnT-negative patients who underwent angiography (p < 0.001), with multivessel disease in 63% versus 13% (p < 0.001). The cTnT-positive patients had a significantly (p < 0.05) higher percent diameter stenosis and a greater frequency of calcified, complex and occlusive lesions. Follow-up was available in 405 patients (98%). By one year, 59 patients (14.6%) had adverse cardiac events. The cumulative adverse event rate was 32.4% in cTnT-positive patients versus 12.8% in cTnT-negative patients (p = 0.001). After adjustment for baseline clinical characteristics, positive cTnT was a stronger predictor of events (chi-square = 23.56, p = 0.0003) than positive CK-MB (>5 ng/ml) (chi-square = 21.08, p = 0.0008). In a model including both biochemical markers, CK-MB added no predictive information as compared with cTnT alone (chi-square = 23.57, p = 0.0006). CONCLUSIONS In a group of patients with chest pain anticipated to have a low prevalence of CAD and a good prognosis, cTnT identifies a subgroup with a high prevalence of extensive and complex CAD and increased risk for long-term adverse outcomes.