Increased FDG-PET/CT pericardial uptake identifies acute pericarditis patients at high risk for relapse

We aimed to evaluate the prognostic value of FDG pericardial uptake using FDG-PET/CT in patients admitted for acute pericarditis with pericardial effusion. In this monocentric retrospective cohort study, all patients admitted for idiopathic acute pericarditis with pericardial effusion from January 2009 to December 2016 who underwent a FDG-PET/CT at diagnosis were considered. Pericardial FDG uptake was measured by generating a volume of interest to calculate the maximal standardized uptake value. The primary outcome was the pericarditis relapse rate during follow-up. FDG-PET/CT was performed 23 [7–99] days after diagnosis in 39 patients (52 [18–83] years, 43.6% of women) admitted for acute pericarditis with pericardial effusion. During a median follow-up period of 7.6 [2.4–77.2] months, 7 (17.9%) patients suffered pericarditis relapse that occurred 3.8 [1.6–14.6] months after FDG-PET CT. In the multivariable analysis, pericardial FDG uptake at diagnosis (OR: 16.6; 95% confidence interval [CI]: 1.25 to 220.8; p = 0.033) was independently associated with pericarditis relapse. Eventually, patients with pericardial FDG uptake at diagnosis had a higher recurrence rate during follow up (p = 0.047). In acute pericarditis with pericardial effusion, increased FDG-PET/CT pericardial uptake is associated with a higher risk for relapse. •Pericarditis relapse is a major complication of acute pericarditis•Relapsing pericarditis is ascribed to an auto-inflammatory process•FDG-PET CT is the mainstay diagnostic test for nuclear imaging of cardiac inflammation•FDG-PET CT pericardial uptake identifies patients at risk for pericarditis relapse