BACKGROUND: The role of inflammatory markers is not well defined for either diagnosis or treatment of pericarditis. The aim of this study is to prospectively evaluate the frequency of high-sensitivity C-reactive protein (hs-CRP) elevation in patients with acute pericarditis, its time course of normalization, and the possible importance for diagnosis, therapy, and prognosis.

METHODS AND RESULTS: Two hundred consecutive patients with viral or idiopathic acute pericarditis (mean age, 53 ± 15.5 years; 103 men) were studied from August 2005 to August 2007 in 2 Italian referral centers. Hs-CRP was determined at presentation and then every week until normalization. Hs-CRP elevation was recorded in 156 of 200 cases (78%) at presentation. Recognized causes of a negative hs-CRP at presentation were early assessment in 15 of 44 cases (34%) and previous anti-inflammatory therapies in 22 of 44 cases (50%). Hs-CRP normalization was achieved with the following time course: 120 of 200 (60%) at week 1, 170 of 200 (85%) at week 2, 190 of 200 (95%) at week 3, and all cases (100%) at week 4. In multivariable analysis, incomplete response to empirical anti-inflammatory therapy at week 1 (hazard ratio, 2.98; 95% confidence interval, 1.80 to 4.94; P < 0.001), corticosteroid therapy (hazard ratio, 2.80; 95% confidence interval, 1.59 to 4.95; P < 0.001), and the presence of elevated hs-CRP at week 1 (hazard ratio, 2.36; 95% confidence interval, 1.32 to 4.21; P = 0.004) were independent risk factors for recurrence.

CONCLUSIONS: Hs-CRP is elevated at the initial presentation in ≈ 3 of 4 cases of acute pericarditis, identifies patients at higher risk of recurrence, and could be used to monitor disease activity and select appropriate therapy length.