Predictive value of C-reactive protein and troponin T in patients with unstable angina: a comparative analysis

Abstract

OBJECTIVES: We evaluated C-reactive protein (CRP) and troponin T (TnT) for predicting six-month cardiac risk in patients with unstable angina. BACKGROUND: Troponin T is predictive of cardiac risk in patients with unstable angina. The clinical implications of elevated CRP in such patients remains controversial. METHODS: Baseline TnT and CRP values were determined in 447 patients with unstable angina enrolled in the placebo group of the Chimeric c7E3 AntiPlatelet Therapy in Unstable angina REfractory to standard treatment trial (CAPTURE) trial. All patients underwent a coronary intervention and were followed for a six month period in which 13 deaths and 47 myocardial infarctions were documented (MIs). RESULTS: Troponin T was >0.1 microg/liter in 30% and CRP was >10 mg/L in 41% of the patients. For the initial 72-h period (including coronary intervention), TnT (17.4% vs. 4.2%; p < 0.001) but not CRP (10.3% vs. 8%; p = 0.41) was predictive of mortality and MI. The TnT-positive patients displayed more frequent recurrent instability before the planned intervention (44.8% vs. 16.9%; p < 0.001), but in the CRP-positive patients, no such increase was observed (25.9% vs. 24.8%; p = 0.92). In contrast, for the six month follow-up period, CRP was predictive of cardiac risk (mortality, MI) (18.9% vs. 9.5%; p = 0.003). Using multivariate analysis, both CRP and TnT emerged as independent predictors of mortality and MI at six-month follow-up. Furthermore, the incidence of coronary restenosis during six-month follow-up was not related to TnT status (3% vs. 4.5%; p = 0.49); however, it was significantly related to CRP status (7% vs. 2.3%; p = 0.03). CONCLUSIONS: Troponin T, but not CRP, was predictive of cardiac risk during the initial 72-h period, whereas CRP was an independent predictor of both cardiac risk and repeated coronary revascularization (coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty) during six month follow-up.