Acute pericarditis with pleuropulmonary involvement, fever and elevated C-reactive protein: A systemic autoinflammatory disease? A cohort study

Objectives: This cohort study describes a systemic phenotype of pericarditis, comparing this phenotype with other forms of pericarditis. Patients and methods: Patients in our center were enrolled in a prospectively maintained registry from 2019 to 2022. 412 patients with idiopathic recurrent pericarditis were analyzed. "Systemic inflammatory" subset was defined as the presence of all the following criteria: fever ≥38C°, CRP ≥2 times normal values, pleural effusion detected with any imaging techniques. The absence of any of the 3 criteria was defined as "isolated" subset. Results: We found that 211 (51.2%) of 412 patients (188 female) presented the systemic subset and the variables significantly associated with this subset in univariate analysis (p<0.001) were: higher mean age: 45.5 (±SD 17.2) vs 39.9 (±SD 16.4) years, higher mean CRP values: 128.8 vs 49.9 mg/L, higher proportion of pericardiocentesis: 19% vs 1.5%, higher mean leukocyte count: 13,143.3 vs 9910.3/mm3, higher mean neutrophils number: 10,402.5 vs 6779.8 /mm3 and lower mean lymphocyte count: 1693.9 vs 2079.3 /mm3. As results the neutrophil-to-lymphocyte ratio was higher in systemic inflammatory phenotype: 6.6 vs 3.4 (p< 0.001). Anti-IL1 therapy was started more frequently in the systemic subgroup (26%) than in the isolated subset (7.5%) (p < 0.001). On multivariate analysis neutrophil count and lymphopenia were statistically associated with the systemic subset (p < 0.001). Conclusion: This results demonstrate the relevance of the systemic inflammatory phenotype, characterized by pleural effusions, confirming its analogy with autoinflammatory diseases, thus possibly requiring an eventual escalation of therapy to IL-1 inhibitors.