Outcomes of idiopathic chronic large pericardial effusion.

Objective: Aim of this paper is to evaluate the outcomes of 'idiopathic' chronic large pericardial effusions without initial evidence of pericarditis.

Methods: All consecutive cases of idiopathic chronic large pericardial effusions evaluated from 2000 to 2015 in three Italian tertiary referral centres for pericardial diseases were enrolled in a prospective cohort study. The term 'idiopathic' was applied to cases that performed a complete diagnostic evaluation to exclude a specific aetiology. A clinical and echocardiographic follow-up was performed every 3-6 months.

Results: 100 patients were included (mean age 61.3±14.6 years, 54 females, 44 patients were asymptomatic according to clinical evaluation) with a mean follow-up of 50 months. The baseline median size of the effusion (evaluated as the largest end-diastolic echo-free space) was 25 mm (IQR 8) and decreased to a mean value of 7 mm (IQR 19; p<0.0001) with complete regression in 39 patients at the end of follow-up. There were no new aetiological diagnoses. Adverse events were respectively: cardiac tamponade in 8 patients (8.0%), pericardiocentesis in 30 patients (30.0%), pericardial window in 12 cases (12.0%) and pericardiectomy in 3 patients (3.0%). Recurrence-free survival and complications-free survival was better in patients treated without interventions (log rank p=0.0038).

Conclusions: The evolution of 'idiopathic' chronic large pericardial effusions is usually benign with reduction of the size of the effusion in the majority of cases, and regression in about 40% of cases. The risk of cardiac tamponade is 2.2%/year and recurrence/complications survival was better in patients treated conservatively without interventions.