What are the guidelines for subsegmental Pulmonary Embolism (PE)?

From the Guidelines

Subsegmental pulmonary embolism (PE) should be treated with anticoagulation therapy in most patients, particularly those with risk factors for recurrence or progression, as recommended by the most recent guidelines 1. The standard anticoagulation regimen includes initial treatment with low molecular weight heparin (such as enoxaparin 1 mg/kg twice daily) or direct oral anticoagulants (DOACs) like rivaroxaban (15 mg twice daily for 21 days, then 20 mg daily), apixaban (10 mg twice daily for 7 days, then 5 mg twice daily), or edoxaban (60 mg daily after 5 days of parenteral anticoagulation) 1. Some key points to consider when deciding on anticoagulation for subsegmental PE include:

• The certainty of the diagnosis, with features such as multiple intraluminal defects, defects involving more proximal subsegmental arteries, and defects seen on more than one image, favoring true-positive findings 1
• The presence of risk factors for recurrent or progressive VTE, such as active cancer, reduced mobility, or pregnancy, which may favor anticoagulation 1
• The patient's cardiopulmonary reserve and symptoms, with those having low reserve or marked symptoms favoring anticoagulant therapy 1
• The risk of bleeding, with those having a high risk favoring no anticoagulant therapy 1 Treatment duration is typically 3 months for provoked PE and at least 3-6 months or longer for unprovoked PE, with the decision to extend treatment based on the balance of benefits and risks, including the patient's preference 2. In select cases of isolated subsegmental PE with low risk factors and adequate cardiopulmonary reserve, close monitoring without anticoagulation may be considered, but this approach requires careful patient selection and follow-up 1. Anticoagulation is recommended because even small clots can propagate, and subsegmental PEs are associated with recurrent venous thromboembolism, and the diagnostic certainty of subsegmental PE on CT imaging can be limited, making treatment the safer approach in most clinical scenarios 1.

From the Research

PE Guidelines for Subsegmental Pulmonary Embolism

• The management of subsegmental pulmonary embolism (SSPE) is controversial, with some studies suggesting that anticoagulation therapy may not be necessary for all patients 3, 4.
• The clinical context of the patient, including risk factors, alternative indications, and illness severity, plays a significant role in determining the need for anticoagulation therapy 3.
• Studies have shown that patients with SSPE who receive anticoagulation therapy have a different clinical context compared to those who do not receive anticoagulation, including higher rates of previous venous thromboembolism, recent surgery, and elevated serum D-dimer 3.
• The mortality rate for patients with SSPE is high, regardless of anticoagulation, due to coexistent disease processes rather than the SSPE itself 3.
• Current clinical practice guidelines suggest an individualized approach to managing patients with SSPE, taking into account the risk/benefit ratio and carefully assessing the patient's clinical context 4.
• There is a lack of randomized controlled trial evidence to support the effectiveness and safety of anticoagulation therapy versus no intervention in patients with SSPE or incidental SSPE 5, 6, 7.