Temporal clustering of recurrences after a first episode of acute pericarditis.

INTRODUCTION: Recurrent pericarditis represents the most challenging complication following an initial episode of acute pericarditis, occurring in up to 30% of patients. Although the risk of recurrence is considered elevated for as long as two years after the index episode, the temporal distribution of recurrences has not been systematically investigated. METHODS: We conducted a single-center, prospective observational study including consecutive patients hospitalized for a first documented episode of acute pericarditis, who were subsequently followed for at least two years. During follow-up, the occurrence and type of recurrence (incessant or recurrent pericarditis) were recorded. The primary outcome was pericarditis recurrence. To assess the temporal pattern of recurrence risk, patients were categorized into early recurrence (≤3 months from the index episode) and late recurrence (>3 months to 2 years). RESULTS: We enrolled 272 patients (mean age 59.5 ± 18.5 years; 58% men) who were prospectively followed. The median follow-up was 51 months [IQR 21-71]. A markedly front-loaded recurrence pattern was observed with 86.8% of all recurrences occurring within the first 3 months after the index episode. The median time to recurrence was 35 days (IQR 30-60). Patients with early recurrence exhibited significantly higher peak CRP levels during the initial hospitalization (p = 0.012) and were more likely to present with fever (p = 0.017). CONCLUSIONS: The burden of pericarditis recurrence is concentrated within the first 3 months following the initial episode. These findings support the need for intensified monitoring, careful treatment tapering and follow-up planning during the early post-acute phase.