Identification of Low-risk Patients With Acute Symptomatic Pulmonary Embolism

Background: Identification of patients with acute symptomatic pulmonary embolism (PE) who are at low-risk for short-term complications to warrant outpatient care lacks clarity. Method: In order to identify patients at low-risk for 30-day all-cause and PE-related mortality, we used a cohort of haemodynamically stable patients from the RIETE registry to compare the false-negative rate of four strategies: the simplified Pulmonary Embolism Severity Index (sPESI); a modified (i.e., heart rate cutoff of 100 beats/min) sPESI; and a combination of the original and the modified sPESI with computed tomography (CT)-assessed right ventricle (RV)/left ventricle (LV) ratio. Results: Overall, 137 of 3117 patients with acute PE (4.4%) died during the first month. Of these, 41 (1.3%) died from PE, and 96 (3.1%) died from other causes. The proportion of patients categorized as having low-risk was highest with the sPESI and lowest with the combination of a modified sPESI and CT-assessed RV/LV ratio (32.5% versus 16.5%; P < 0.001). However, among patients identified as low-risk, the 30-day mortality rate was lowest with the combination of a modified sPESI and CT-assessed RV/LV ratio and highest with the sPESI (0.4% versus 1.0%; P = 0.03). The 30-day PE-related mortality rates for patients designated as low-risk by the sPESI, the modified sPESI, and the combination of the original and modified sPESI with CT-assessed RV/LV ratio were 0.7%, 0.4%, 0.7%, and 0.2%, respectively. Conclusions: The combination of a negative modified sPESI with CT-assessed RV/LV ratio ≤1 identifies patients with acute PE who are at very low-risk for short-term mortality.