Clinical Decision Guidelines
Background: Pericardial effusions can vary widely in clinical importance when encountered in the emergency department (ED) and determining which patients require urgent intervention often remains challenging. The purpose of this study was to create a prediction score to risk stratify patients with pericardial effusion.
Methods: This was a retrospective cohort study of adult patients who presented to an urban academic ED and were found to have a non-traumatic pericardial effusion ≥ 1cm in diastole on comprehensive transthoracic echocardiogram (TTE). Electronic medical records and TTE images were reviewed blinded to in-hospital events. The primary outcome was a pericardial drainage procedure or death attributed to pericardial tamponade within 24 hours of ED arrival. The overall cohort was divided into a derivation and validation cohort and logistic regression was applied for the generation and validation of the risk score. Area under the receiver-operating characteristic curve (c-statistic) was used to assess the performance of the model in the derivation and validation cohorts.
Results: Among 195 patients (mean age 60, 51% men, 81% White) who met the inclusion criteria, 102 (52%) experienced the primary outcome, none of whom died within 24 hours. Four variables were selected for inclusion in the final model: systolic blood pressure < 100mmHg [1.5 points], effusion diameter category (1-2cm [0 points], 2-3cm [1.5 points], > 3cm [2 points]), right ventricular diastolic collapse [2 points], and mitral inflow velocity variation > 25% [1 point]. The risk of requiring pericardial drainage within 24 hours was stratified as low (< 2 points), intermediate (2-4 points) and high (≥ 4 points), which corresponded to risks of 8.1% (95%CI 3.0-16.8%), 63.8% (95%CI 50.1-76.0%) and 93.7% (95%CI 84.5-98.2%) in the combined cohort. The derivation cohort had a c-statistic of 0.94 and the validation cohort had a c-statistic of 0.91.
Conclusion: Among ED patients with moderate or large pericardial effusion, a simple prediction score consisting of systolic blood pressure, effusion diameter, right ventricular collapse, and mitral inflow velocity variation can accurately predict the need for urgent pericardial drainage. Prospective validation of this novel score is warranted.