Clinical, Echocardiographic, and Procedural Characteristics of Eccentric Versus Circumferential Pericardial Effusions in a Symptomatic Drainage Cohort.

BACKGROUND: Eccentric pericardial effusions are non-circumferential fluid collections that may complicate conventional pericardiocentesis, yet the associated clinical characteristics remain poorly defined. METHODS: This single-center retrospective comparative cohort study included adult patients with symptomatic pericardial effusion of undetermined etiology who underwent percutaneous pericardiocentesis under transthoracic echocardiographic or fluoroscopic guidance or a surgical pericardial window procedure. Based on preprocedural multi-view transthoracic echocardiography (TTE), effusions were classified as eccentric or circumferential. Baseline characteristics, imaging features, procedural outcomes, pericardial fluid analyses, etiologies, and short-term outcomes were compared. Univariable and multivariable logistic regression analyses were performed to identify factors associated with eccentric distribution. RESULTS: Among 156 patients, 47 (30.1%) had eccentric pericardial effusions. In multivariable analysis, a chronic course (odds ratio (OR) 6.31, 95% confidence interval (CI) 2.68-14.85; p < 0.001) and higher body temperature (per 1 °C increase: OR 2.52, 95% CI 1.13-5.63; p = 0.024) were independently associated with eccentric effusion. Compared with circumferential effusions, eccentric effusions showed a different distribution of dominant maximal-depth sites (overall p = 0.026), with a higher proportion of maximal depth located along the left ventricular lateral wall (57.45% vs. 33.03%). Eccentric effusions also had a shallower anterior echo-free space (5 [3-7] vs. 11 [7-15.9] mm, p < 0.001), and showed fewer classic tamponade signs, including right ventricular diastolic collapse (12.77% vs. 39.45%, p < 0.001). Procedurally, eccentric effusions more frequently required fluoroscopic guidance (44.68% vs. 10.09%, p < 0.001), had lower drainage volumes (600 mL vs. 914 mL, p = 0.005), and showed a higher incidence of poor drainage (44.68% vs. 8.26%, p < 0.001). The etiologic spectrum of eccentric effusions was more heterogeneous and less likely to be malignant (31.91% vs. 55.96%). In-hospital and 90-day outcomes were comparable between groups. CONCLUSIONS: In this symptomatic drainage cohort, eccentric pericardial effusions were associated with a chronic course and higher body temperature and were characterized by left ventricular lateral predominance, fewer classic echocardiographic signs of tamponade, and greater reliance on fluoroscopic guidance for drainage. The etiologic spectrum of eccentric effusions was more heterogeneous and less likely to be malignant.