title: A small pericardial effusion is a marker of increased mortality.
abstract: OBJECTIVE
  the study aimed to evaluate the prognostic importance of an incidental small pericardial effusion found on echocardiography.
  
  
  METHODS
  we identified 10,067 consecutive patients undergoing echocardiography at 1 of 3 laboratories. Patients were excluded if they were referred for evaluation of the pericardium (n = 133), had cardiac surgery within the previous 60 days (n = 393), had a moderate or greater pericardial effusion (>1 cm if circumferential, n = 29), had no follow-up (n = 153), or had inadequate visualization of the pericardial space (n = 9). The Social Security Death Index was used to determine survival.
  
  
  RESULTS
  a small pericardial effusion was noted in 534 (5.7%) of 9,350 patients. Compared to patients without a small effusion, those with an effusion were slightly older (68 ± 13 vs 67 ± 12 years, P = .02) and had a lower ejection fraction (52% vs 55%, P < .0001). Mortality at 1 year was greater for patients with a small effusion (26%) compared to those without an effusion (11%, P < .0001). After adjustment for demographics, medical history, patient location, and other echocardiographic findings, small pericardial effusion remained associated with higher mortality (hazard ratio 1.17, 95% CI 1.09-1.28, P = .0002). Of 211 with an effusion and follow-up echocardiography (mean 547 days), 136 (60%) had resolution, 63 (28%) showed no change, and 12 (5%) had an increase in size, although no patient developed a large effusion or cardiac tamponade.
  
  
  CONCLUSIONS
  the presence of a small asymptomatic pericardial effusion is associated with increased mortality.
authors.affiliation: Yale University School of Medicine, Department of Internal Medicine, Section of Cardiovascular Medicine, Stanford University, Stanford, CA, USA.
authors.forename: Teferi Y
authors.initials: TY
authors.lastname: Mitiku
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heidenreich
mesh_terms: D000368:Aged; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010490:Pericardial Effusion / Q000000981:diagnostic imaging* / Q000401:mortality*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014481:United States / Q000453:epidemiology