C-reactive protein and cardiac troponin T in risk stratification: Differences in optimal timing of tests early after the onset of chest pain

Background: Increased C-reactive protein (CRP) is an important prognostic i ndicator for early risk stratification in patients with an acute coronary s yndrome (ACS), independent of, and in combination with, increased cardiac t roponin T (cTnT). However, increases in both cTnT and CRP also occur second ary to myocardial damage. Methods and Results: In 156 consecutive patients, early release kinetics of CRP and cTnT were analyzed. The cutoff values were 3.0 mg/L for CRP and 0. 1 mu g/L for cTnT. In the 75 patients with a CRP below the cutoff on admiss ion, there was little change in CRP until 8 h after the onset of symptoms. At 12 h after the onset of symptoms, the cumulative proportions of abnormal CRP and cTnT in non-ST elevation ACS patients were 27% and 89%, respective ly (P <0.01). During the first 24 h after the onset of symptoms, the median time above the cutoff was 20 h for CRP and 5 h for cTnT (P <0.0001). CRP w as below the cutoff on admission significantly more often among patients re ceiving thrombolytic therapy than in patients without an indication for rep erfusion therapy (51% vs 28%; P = 0.004). Conclusions: Increased CRP as an early independent risk indicator should be measured as soon as possible after the onset of symptoms, whereas increase d cTnT is most reliable at 12 or more hours after the onset of symptoms. (C ) 2000 American Association for Clinical Chemistry.