Descriptions of Etiology, Clinical Course, and Prognosis of Patients Presenting with Pericardial Effusion.

Pericardial effusion (PE) presentation varies from an incidental finding to a life-threatening situation; thus, its etiology and clinical course remain unknown. The aim of the present study was to retrospectively investigate these factors.We analyzed 171 patients (0.4%) who presented with PE among 34,873 patients who underwent echocardiography between 2011 and 2021 at our hospital. Clinical and prognostic information was retrieved from electronic medical records. The primary endpoints were all-cause death, hospitalization due to heart failure (HF), and other cardiovascular events such as cardiovascular death, acute coronary syndrome, elective percutaneous coronary intervention, and stroke.The etiologies of PE were as follows: idiopathic (32%), HF-related (18%), iatrogenic (11%), cardiac surgery-related (10%), radiation therapy-related (9%), malignancy (8%), pericarditis/myocarditis (8%), myocardial infarction-related (2%), and acute aortic dissection (2%). Patients with idiopathic/HF etiology were more likely to be older than the others.During a mean follow-up period of 2.5 years, all-cause death occurred in 21 patients (12.3%), cardiovascular events in 10 patients (5.8%), and hospitalization for HF in 24 patients (14.0%). All-cause death was frequently observed in patients with malignancy (44% per person-year). Cardiovascular events were mostly observed in patients with radiation therapy-related and malignancy (8.6% and 7.3% per person-year, respectively).The annual incidence of hospitalization for HF was the highest in patients with HF-related (25.1% per person-year), followed by radiation therapy-related (10.4% per person-year).This retrospective study is the first, to the best of our knowledge, to reveal the contemporary prevalence of PE, its cause, and outcome in patients who visited a cardiovascular hospital in an urban area of Japan.