Some patients with acute pulmonary embolism (PE) will suffer adverse clinical outcomes despite being low risk by clinical decision rules. Emergency physician decisionmaking processes regarding which low-risk patients require hospitalization are unclear. Higher heart rate (HR) or embolic burden may increase short-term mortality risk, and we hypothesized that these variables would be associated with an increased likelihood of hospitalization for patients designated as low risk by the PE Severity Index.

This was a retrospective cohort study of 461 adult emergency department (ED) patients with a PE Severity Index score of fewer than 86 points. Primary exposures were the highest observed ED HR, most proximal embolus location (proximal vs distal), and embolism laterality (bilateral vs unilateral PE). The primary outcome was hospitalization.

Of 461 patients meeting inclusion criteria, most (57.5%) were hospitalized, 2 patients (0.4%) died within 30 days, and 142 (30.8%) patients were at elevated risk by other criteria (Hestia criteria or biochemical/radiographic right ventricular dysfunction). Variablesassociated with an increased likelihood of admission were highest observed ED HR of ≥110 beats/minute (vs HR <90 beats/min) (adjusted odds ratio [aOR] 3.11; 95% confidence interval [CI] 1.07 to 9.57), highest ED HR 90 to 109 (aOR 2.03; 95% CI 1.18-3.50) and bilateral PE (aOR 1.92; 95% CI 1.13 to 3.27). Proximal embolus location was not associated with the likelihood of hospitalization (aOR 1.19; 95% CI 0.71 to 2.00).

Most patients were hospitalized, often with recognizable high-risk characteristics not accounted for by the PE Severity Index. Highest ED HR of ≥90 beats/min and bilateral PE were associated with a physician’s decision for hospitalization.