Pericarditis recurrence is associated with milder electrocardiographic, echocardiographic, and laboratory findings.

Recurrent pericarditis (RP) complicates approximately 30% of acute pericarditis (AP) cases. We sought to compare the prevalence and severity of objective findings seen in patients with RP. A retrospective single-center study during 2010-2019, including 765 patients diagnosed with AP. Clinical, electrocardiographic, echocardiographic, and laboratory findings were extracted from the local electronic health records. Recurrence during follow-up was documented in 134 patients (17.5%), with a median time to recurrence of 101 (± 59-251) days. The median age was 60 years (IQR 45-72), 68% were male. Most patients were defined as having idiopathic\viral pericarditis (64%). The clinical manifestation during the recurrent event of pericarditis was less prominent or attenuated when compared to the initial event-ECG signs (ST elevation 12% vs. 26%; p = 0.006, Knuckle sign 13% vs. 33%; p < 0.001, ST larger in lead L2 than L3 4% vs. 19%; p < 0.001), pericardial effusion moderate and above (11% vs. 30%; p = 0.02), and inflammatory markers (mean peak CRP levels 66 mg/l vs. 97 mg/l; p < 0.001). Similar results were seen in the subgroup of patients defined as having idiopathic\viral pericarditis. Up to 20% of patients who did not have ECG signs or a significant pericardial effusion in their 1st event demonstrated these findings during the recurrence, though still to a lesser extent compared with those who had these signs in their 1st event. The objective findings of AP are less pronounced during recurrent events. Future studies should focus on the role of advanced biomarkers and imaging in defining true RP events.