Nationwide outcomes after first-time pericarditis: recurrence, rehospitalization, and mortality in a danish registry cohort

Background Pericarditis is the most common disease of the pericardium and a frequent cause of acute cardiovascular consultation. Although often considered self-limiting, recurrence and adverse outcomes may occur, particularly in patients with underlying comorbidity. Contemporary population-level data describing patient characteristics, comorbidity burden, biomarker profile, and clinical outcomes following first-time pericarditis remain limited. Purpose To characterize patients hospitalized with first-time pericarditis and evaluate recurrence, all-cause rehospitalization, and mortality within one year in a nationwide, unselected population. Methods Using nationwide Danish health registries covering the entire Danish population from 2000–2018, we identified patients with a first-time in-hospital diagnosis of pericarditis. Baseline comorbidities, dispensed prescriptions 6 months prior to diagnosis, and biomarkers were assessed. Patients were followed for one year after discharge with complete nationwide follow-up. Outcomes were recurrent pericarditis requiring hospitalization, all-cause rehospitalization, and death. Results We included 16,192 patients. Median age was 52.9 years (IQR 36.3–66.8), and 69.3% were men, demonstrating a marked male predominance. Comorbidity burden was substantial, including ischemic heart disease (21.0%), atrial fibrillation (14.4%), malignancy (12.4%), heart failure (9.0%), and prior myocardial infarction (9.7%). Within 6 months prior to diagnosis, 19.2% had redeemed a prescription for NSAIDs and 0.3% had redeemed a prescription for colchicine. Median troponin T was 16 ng/L, troponin I 15 ng/L, and C-reactive protein 64 mg/L, indicating modest biomarker elevations at presentation despite significant subsequent clinical risk. Within one year, 14.1% had recurrent pericarditis requiring hospitalization and 48.2% were rehospitalized for any cause. Median time to recurrent pericarditis was 13 days (IQR 4–38), and median time to rehospitalization was 23 days (IQR 7–94), indicating frequent early clinical deterioration following discharge. One-year mortality was 7.7%. Conclusion In this large nationwide cohort, patients hospitalized with first-time pericarditis were predominantly middle-aged men with substantial cardiovascular comorbidity and malignancy, reflecting a clinically vulnerable population. Recurrent pericarditis and rehospitalization were common within one year, often occurring early after discharge, and mortality was considerable. These findings demonstrate that first-time pericarditis is associated with substantial early morbidity, mortality, and healthcare burden, highlighting the need for improved risk stratification, management, and structured follow-up.