BACKGROUND: Patients with pericarditis may show elevation of C-reactive protein (CRP) and pericardial effusion at presentation. There are limited data on the prognostic implications of this inflammatory phenotype. OBJECTIVES: Aim of the present study is to evaluate the outcome of the inflammatory phenotype in a cohort of patients with acute pericarditis. METHODS: Observational cohort study of consecutive adult patients with acute pericarditis in 4 referral centers for pericarditis (Athens, Milan, Turin, Udine). RESULTS: Our cohort included 918 patients with acute pericarditis (median age of 56, IQR 28 years, 55.6 % females). The etiology of pericarditis was respectively idiopathic in 82.1 %, post-cardiac injury syndrome in 9.3 %, and systemic inflammatory disease in 4.9 % of cases. CRP elevation was detected at presentation in 778 cases (84.7 %), an inflammatory phenotype (CRP elevation and pericardial effusion) was found in 557 patients (60.7 %). Baseline medical therapy included a NSAID in 74.9 %, colchicine 70.9 %, and corticosteroids 25.1 % of cases. After a mean follow-up of 22.5 months, patients with an inflammatory phenotype had a higher recurrence rate at 18 months (respectively 46.0 % vs. 31.0 %
p <
0.0001), and a shorter recurrence-free survival (Log-rank p = 0.0001). In multivariable analysis the inflammatory phenotype presentation was independently associated with an increased risk of recurrences (OR 2.005, 95 % CI 1.454 to 2.765
p <
0.0001). CONCLUSIONS: The inflammatory phenotype of presentation of acute pericarditis is associated with an increased risk of recurrences, highlighting the importance of timely individualized therapy and close follow-up for these patients.