Time-to-start of anticoagulant therapy and mortality in pulmonary embolism

Pulmonary embolism (PE) is a significant cause of mortality. Prior studies indicate that initiating anticoagulant therapy in the emergency department (vs after admission) may reduce mortality. Therefore, the time-to-start of anticoagulant therapy may be a modifiable risk factor contributing to PE-related mortality.

We aimed to quantify the association between the delay in the time from symptom presentation of acute PE to the start of anticoagulant therapy and the risk of PE-related mortality.

We conducted a multicenter retrospective cohort study of patients presenting with acute intermediate- or high-risk PE who received initial treatment with low-molecular-weight or unfractionated heparin between June 2020 and September 2024. Logistic regression quantified the association between 30-day PE-related mortality and time from presentation to anticoagulant initiation.

A total of 562 patients met the inclusion criteria. Eleven percent (n = 64) died within 30 days from PE-related causes. The geometric mean time from acute care presentation to the start of anticoagulant therapy was 225 minutes in survivors vs 284 minutes in those who died (P = .067). After controlling for PE severity, simplified PE Severity Index, renal function, thrombectomy, and anticoagulant type, each doubling of time to the start of anticoagulant therapy was associated with a 1.38-fold increase in the odds of PE-related death (95% CI, 1.05-1.82; P = .021). Among intermediate-risk patients (n = 434), each doubling of time to the start of anticoagulant therapy was associated with a 2.4-fold increase in the odds of PE-related death (95% CI, 1.44-3.96; P < .001).

In patients presenting to the acute care setting with intermediate- or high-risk PE, delay in the start of anticoagulant therapy is independently associated with increased odds of PE-related mortality. Quality improvement initiatives reducing the time-to-start of anticoagulant therapy are warranted.