Clinical Significance of Plasma C-reactive Protein Level in Patients with Acute Idiopathic Pericarditis

Background: The plasma level of C-reactive protein (CRP) is frequently increased in patients with acute idiopathic pericarditis (AIP). However, the value of elevated CRP level for the diagnosis of AIP and the possible clinical significance of peak plasma CRP levels are not well established. The aim of this retrospective analysis was to examine the frequency of elevated plasma CRP levels according to time from symptom onset and the possible prognostic significance of peak plasma CRP levels in patients with AIP.

Methods and results: The study examined a cohort of consecutive patients who were admitted to the hospital with a diagnosis of AIP between January 1, 2007, and December 31, 2016. The final cohort included 241 patients (age: 18-89 years; 181 males). Plasma CRP levels and data on the time of onset of pericarditis symptoms were available for 202 patients. The range of peak CRP level was 0.1-39.0 mg/dL, and the levels were elevated in 97.8% of the patients. Linear regression analysis revealed that fever and age were independently associated with CRP levels. CRP levels remained normal in only 1 of the 147 patients (0.68%) who had pericardial effusion, as opposed to 4 of 76 patients (5.3%) without this finding (p=0.0471). MACE was independently associated with plasma CRP levels and was much more common in patients with peak plasma CRP levels above the median (24 of 113, 21.2% vs. 5 of 112, 4.5%, p=0.0002).

Conclusions: Among patients with AIP, peak plasma CRP levels are associated with MACE.

Key words: Acute idiopathic pericarditis; C-reactive protein; pericardial effusion, outcome