Introduction and objectives: Better knowledge of C-reactive protein (CRP) kinetics could lead to improved clinical application of this biomarker.
Methods: We studied 110 patients: 42 had ST-elevation acute myocardial infarction (STEMI), 35 had non-ST-elevation acute myocardial infarction (NSTEMI), and 33 had unstable angina. Patients were admitted to our institution within 6 hours of symptom onset. The levels of CRP, troponin-I, and creatine kinase MB fraction (CK-MB) were measured on admission and every 6 hours during the first 48 h. The CRP level was also measured daily until hospital discharge.
Results: The median (interquartile range) CRP level increased relative to baseline from 6 hours after admission, from 5 (2-9) mg/L to 6 (3-10) mg/L (P=.004). Although, CRP levels on admission were similar in all groups, there was a significant difference in peak CRP level: it was 67 (36-112) mg/L in the STEMI group, 29 (20-87) mg/L in the NSTEMI group, and 18 (12-36) mg/L in the unstable angina group. The maximum CRP level was observed 49 (38-53) hours after the onset of symptoms, but occurred later in patients with STEMI. Although there was only a weak non-significant correlation between CRP and troponin levels (r=0.135) at admission, the maximum CRP level was found to be influenced by the degree of myocardial damage (r=0.496; P< .001).
Conclusions: The pattern of CRP release observed was clearly different in different forms of acute coronary syndrome. Although the CRP level measured at admission was similar in all patient groups, it was influenced by the degree of early myocardial tissue necrosis. This variation in CRP kinetics should be taken into consideration when designing future studies.