The heterozygous in factor II with a small previous incident of pulmonary

For a patient heterozygous for factor II (prothrombin) deficiency with a history of previous pulmonary embolism (PE), anticoagulant treatment should be offered for at least 3 months after the acute event.

After the initial 3 months, the decision to continue anticoagulation should be individualized, based on the balance between the risk of recurrent venous thromboembolism (VTE) and bleeding risk, as well as patient preferences. Patients with an unprovoked PE or persistent thrombophilia, such as factor II deficiency, are often considered for extended anticoagulation beyond the initial 3 months to reduce recurrence risk.

In this context, it is advisable to conduct a thorough risk-benefit discussion, including assessment of bleeding risk (for example, using tools like the HAS-BLED score), patient values, and clinical factors. Long-term anticoagulation can be considered if the risk of recurrence outweighs bleeding risk and if the patient consents to ongoing treatment NICE NG158.

Direct oral anticoagulants (DOACs) such as apixaban or rivaroxaban are recommended first-line agents for treatment and secondary prevention of PE in most patients without contraindications NICE NG158 Miceli et al. 2025. If DOACs are unsuitable, low molecular weight heparins (LMWH) or vitamin K antagonists (VKAs) are alternatives NICE NG158.

Factor II heterozygosity confers approximately a 2- to 3-fold increased thrombotic risk and, when combined with a history of PE, classifies the patient as high risk for recurrence Miceli et al. 2025. Recent literature suggests that patients with this mutation generally benefit from individualized extended anticoagulation, especially if there are no major bleeding contraindications Miceli et al. 2025. Risk stratification tools and D-dimer levels after the initial anticoagulation course may help guide duration decisions.