Objectives: To evaluate the safety of outpatient treatment of patients with very low-risk pulmonary embolism (PE), and the satisfaction and quality of life of this management.

Methods: An experimental study of routine clinical practice will be carried out in which 300 consecutive hemodynamically stable patients with acute symptomatic PE will be included, who meet all the inclusion criteria and none of the exclusion criteria. All patients included in the study will be treated on an outpatient basis, that is, they will be discharged within the first 24 hours of the diagnosis of PE in the Emergency Department. The Computerized Registry of Thromboembolic Disease RIETE (Registro Informatizado de Enfermedad TromboEmbólica) will be used to collect the data in electronic case report form (CRF) and ensure the quality of the data.

Setting: Emergency, Pneumology and Internal Medicine Services of 10 Spanish hospitals.

Analysis: An intention-to-treat (ITT) analysis will be performed on all patients who sign the informed consent and are included in the study (regardless of whether or not they receive the assigned strategy). Additionally, an analysis of all patients who are treated on an outpatient basis without deviations or violations of the protocol will be performed. The primary outcome considered will be the composite of recurrent PE, major bleeding, or death from any cause during the first 30 days after enrollment in the study. Patient satisfaction and quality of life will be considered as secondary outcomes.

Inclusion Criteria:

• Confirmation of suspected pulmonary embolism (PE) by multidetector chest angio computed tomography (CT), if a contrast-encircled partial intraluminal defect or complete pulmonary artery occlusion is demonstrated on two consecutive CT slices (13);
• Right ventricle (RV) diameter equal to or less than that of the left ventricle (LV) (RV/LV ratio ≤1) on chest CT angiography (see Study Procedures); and
• Negatively modified simplified Pulmonary Embolism Severity Index (sPESI) scale at the time of evaluation of the patient in the Emergency Department.

Exclusion Criteria:

• Inability to obtain informed consent
• Pregnancy
• Hemodynamic instability at diagnosis (defined by systolic blood pressure (SBP) <90 mm Hg, indication of fibrinolytic treatment or inferior vena cava filter, need for vasoactive drugs at the discretion of the attending physician, cardiopulmonary resuscitation or orotracheal intubation)
• Contraindication for anticoagulation, at the discretion of the responsible physician;
• Estimated survival of less than 3 months
• Need for thrombectomy, vena cava filter insertion, or need for fibrinolytic treatment of the PE episode at the time of diagnosis
• Participation in a clinical trial for the treatment of venous thromboembolic disease
• Impossibility of follow up