A small pericardial effusion is a marker of increased mortality

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. Conclusion The presence of a small asymptomatic pericardial effusion is associated with increased mortality.