C-reactive protein diagnostic and prognostic value in patients presenting at the emergency room with chest pain

To test immediate diagnostic and prognostic values of C-reactive protein (CRP) in patients admitted to the emergency room (ER) with chest pain (CP) without ST-segment elevation on the electrocardiogram (ECG).

From January 2002 to December 2003, 980 patients were consecutively seen in the ER with CP suggestive of acute coronary syndrome (ACS) (age = 64.9 +/- 14.3, men = 55%, diabetic = 18%, normal ECG = 84%). Serial CRP, creatine kinase MB mass (CKMB-mass) and troponin I determinations were performed on admission, in addition to serial ECG. CRP measurements were standardized (s-CRP) by the upper limit of normal (ULN) of the test used (3.0 mg/L for high-sensitivity C-reactive protein [hs-CRP] and 0.1 mg/dL for titrated CRP [t-CRP]).

One hundred and twenty-five patients were diagnosed with acute myocardial infarction (AMI), and their s-CRP values were 1.31 +/- 2.90 (median = 0.47) compared to 0.79 +/- 1.39 (0.30) in no-AMI patients (p = 0.031). The s-CRP > 1.0 showed 30% sensitivity and 80% specificity, plus negative and positive predictive values of 6.1% and 96.7%, respectively, for AMI diagnosis. There were forty in-hospital cardiac events (16 deaths, 22 urgent revascularizations, and 2 acute myocardial infarction). In the first quartile of the s-CRP (< 0.10), three events were recorded, while in the fourth quartile (> 0.93) 15 events (p = 0.003) occurred. In the logistic regression model, masculine gender and s-CRP > 0.32 (odds ratio 7.6, 2.8 and 2.2, respectively) were independent predictors of cardiac events and left ventricular failure.

In patients with chest pain presenting at the emergency room, s-CRP was not a good marker of AMI, although this diagnosis is virtually excluded by a normal value; in addition, values one-third above the upper limit of normal (>1 mg/L for hs-CRP or >0.33 mg/dL for t-CRP) were predictive of in-hospital adverse cardiac events.