Independent prognostic value of C-reactive protein and troponin I in patients with unstable angina or non-Q-wave myocardial infarction

OBJECTIVES: Elevated concentrations of C-reactive protein (CRP), a non-specific acute phase reactant, and troponin I (TnI), a cardiac-specific marker of myocardial damage, have been found to be associated with a higher risk for cardiac events in patients with an acute coronary syndrome. We evaluated CRP alone and in combination with TnI for predicting the incidence of major cardiac complications within 6 months in patients with unstable angina or non-Q-wave infarction (NQMI). METHODS: CRP and TnI was measured on admission in patients with unstable angina or NQMI, but results were kept blinded. Patients were treated according to a conservative management strategy, and the incidence of major cardiac events within 6 months was assessed. RESULTS: An abnormal CRP (> 5 mg/l) and an abnormal TnI (> 0.4 microgram/l) were more frequent in patients that suffered a major cardiac event (CRP: 93 vs. 35%, P < 0.0001; TnI: 73 vs. 26%, P < 0.001). The incidence of major cardiac events was higher in patients with an abnormal CRP than in patients with a normal CRP, both when TnI was abnormal (42 vs. 4.5%, P = 0.003) and when TnI was normal (11 vs. 0%, P = 0.014). Mean event-free survival was excellent in patients with both a normal CRP and TnI, whereas survival was poorest in patients with both an abnormal CRP and TnI (121 +/- 16 vs. 180 days, P < 0.0001). CONCLUSIONS: An abnormal CRP on admission in patients with unstable angina or NQMI is associated with increased incidence of major cardiac events within 6 months, both in patients with normal and abnormal TnI. CRP and TnI have independent and additive prognostic value in this patient group, and the combination may be useful for early risk stratification.