Relapsing pericarditis: Peripheral blood neutrophilia, lymphopenia and high neutrophil‐to‐lymphocyte ratio herald acute attacks, high‐grade inflammation, multiserosal involvement, and predict multiple recurrences

AimsTo identify peripheral blood cellular correlates of active pericarditis and to verify whether peripheral blood neutrophils, lymphocytes and the neutrophil to-lymphocyte ratio (NLR) are associated with disease phenotype or prognosis. MethodsObservational prospective study on a cohort of 63 patients with idiopathic pericarditis followed for 12 months after each pericarditis recurrence. Two distinct analyses were performed: the "index attack" analysis focused on the first pericarditis episode in each patient, while the "all attacks" analysis included all episodes occurring during the study. ResultsAbsolute and relative neutrophilia and lymphopenia, together with high NLR, were observed during active pericarditis, as compared with disease remission, at both analyses. Neutrophils showed a positive correlation with plasma C-reactive protein levels, while lymphocyte count showed a negative correlation. Relative neutrophil count was higher, and lymphocyte count lower in patients with pleural effusion; a higher NLR and lower absolute lymphocyte count were observed in those with peritoneal involvement. No correlations were found between peripheral blood neutrophil or lymphocyte counts and size of pericardial effusion, or with the presence of myocardial involvement. Peripheral neutrophilia, lymphopenia and NLR during acute attacks predicted the number of recurrences in the following 12 months. ConclusionsPeripheral blood neutrophilia and lymphopenia are typical of acute idiopathic pericarditis. Acute attacks of pericarditis are associated with neutrophilia and lymphopenia, as compared with disease remission. During acute attacks, neutrophilia and lymphopenia reflect the extent of serosal inflammation and could help to customize therapeutic management after remission has been achieved.