For how long should pulmonary embolism (PE) be anticoagulated in the acute phase?

Duration of Anticoagulation in the Acute Phase of Pulmonary Embolism

All patients with pulmonary embolism (PE) should receive therapeutic anticoagulation for at least 3 months. 1

Initial Anticoagulation Duration Based on PE Etiology

• Therapeutic anticoagulation for a minimum of 3 months is recommended for all patients with PE, regardless of etiology 1
• For patients with first PE secondary to a major transient/reversible risk factor, discontinuation of therapeutic oral anticoagulation is recommended after 3 months 1
• For patients with unprovoked PE or proximal DVT, initial anticoagulation should be administered for 3 to 6 months 1
• For patients with unprovoked isolated calf DVT, 3 months of anticoagulation is suggested 1

Extended Anticoagulation Recommendations

• Oral anticoagulant treatment of indefinite duration is recommended for patients with recurrent VTE (at least one previous episode of PE or DVT) not related to a major transient or reversible risk factor 1
• Extended oral anticoagulation of indefinite duration should be considered for patients with a first episode of PE and no identifiable risk factor 1
• Extended oral anticoagulation of indefinite duration should be considered for patients with a first episode of PE associated with a persistent risk factor other than antiphospholipid antibody syndrome 1
• Oral anticoagulant treatment with a VKA for an indefinite period is recommended for patients with antiphospholipid antibody syndrome 1

Risk Stratification for Recurrence

• The circumstances in which PE occurs is the strongest predictor of recurrence risk 1
• Patients with unprovoked venous thrombosis have an annual risk of recurrence >5%, which exceeds the risk of VKA-related bleeding 1
• Patients with PE provoked by surgery are at low risk of recurrence (annual risk <1%) after completing 3 months of treatment 1
• Patients with PE associated with non-surgical risk factors have an intermediate risk of recurrence 1

Special Considerations

• If extended oral anticoagulation is decided after PE in a patient without cancer, a reduced dose of NOACs (apixaban 2.5 mg twice daily or rivaroxaban 10 mg once daily) should be considered after 6 months of therapeutic anticoagulation 1
• For patients with cancer who develop VTE, anticoagulation should be continued indefinitely or until cancer resolves 2
• In patients who receive extended anticoagulation, it is recommended to reassess drug tolerance and adherence, hepatic and renal function, and bleeding risk at regular intervals 1

Common Pitfalls and Caveats

• Failing to recognize that the benefit of anticoagulation continues only for as long as therapy is continued 1
• Not considering the individual patient's bleeding risk when determining duration of anticoagulation 1
• Overlooking that extended anticoagulation may equate to lifelong treatment, or until the perceived risk of bleeding becomes prohibitive 1
• Not routinely re-evaluating patients 3-6 months after acute PE to assess for chronic complications and determine the appropriate duration of anticoagulation 1
• Underestimating the risk of recurrence in patients with unprovoked PE, which may warrant extended anticoagulation despite the absence of other risk factors 3, 4

Emerging Evidence

Recent observational data suggests that extended oral anticoagulation over 2.5 years after index PE provides a net clinical benefit compared with no anticoagulation in selected patients, with similar bleeding rates between extended and non-extended anticoagulation groups 4.