Evaluation of Patients With Acute Chest Pain of Uncertain Origin by Means of Serial Measurements of High-Sensitivity C-Reactive Protein

Abstract

We investigated the usefulness of taking two serial measurements of the high-sensitivity C-reactive protein (hs-CRP) level for evaluating acute chest pain in patients with non-diagnostic ECG findings and normal levels of markers of myocardial cell injury (i.e., an inconclusive diagnosis). We hypothesized that the C-reactive protein concentration would be raised if symptoms were due to coronary endothelial damage or arteriosclerotic plaque rupture. The study involved 468 consecutive patients who presented to the emergency department with acute chest pain, 191 of whom had an inconclusive diagnosis. In this patient group, we determined the hs-CRP level on emergency admission and at 24 hours. Standard guidelines on managing acute chest pain of suspected coronary origin were followed. Any increase in hs-CRP level between baseline and 24 hours was regarded as a positive result. In total, 38 (20%) patients were diagnosed with chest pain due to coronary disease. Measurement of the hs-CRP level differential (i.e., the hs-CRP level at 24 hours minus the baseline level at emergency admission) had a sensitivity of 95% (95% confidence interval [CI] 81-98%), a specificity of 40% (95% CI, 32-47%), a positive likelihood ratio of 1.57 (95% CI, 1.33-1.83), a negative likelihood ratio of 0.13 (95% CI, 0.04-0.44), and an area under the receiver operating characteristic curve of 0.77 (95% CI, 0.69-0.85). By 30-day follow-up, no cardiac event had occurred in patients with a negative hs-CRP level differential. Measurement of the hs-CRP level differential is diagnostically useful in patients with acute chest pain of likely coronary origin. A negative result is associated with a low risk of ischemic heart disease and would allow patients to be discharged safely from the emergency department.