After acute pulmonary embolism (PE) treatment with parenteral anticoagulation followed by oral therapy, decisions about chronic anticoagulation balance the risk of recurrent venous thromboembolism (VTE) against the risk of bleeding. PE recurrence rates vary by underlying provoking factors: cumulative recurrence at 5 years is approximately 3-5% for PE provoked by major transient factor (surgery, immobilization >3 days, hospitalization with active illness, major trauma, cesarean section), 15-25% for unprovoked PE, and 30-40% for PE associated with persistent risk factor (active cancer until cancer-free, antiphospholipid syndrome, severe thrombophilia, recurrent unprovoked VTE). Individual risk stratification considers patient-specific factors: D-dimer level after stopping anticoagulation, residual venous obstruction, sex (male higher recurrence), provoking factor type, and severity (saddle, hemodynamic compromise, RV dysfunction).
Bleeding risk assessment uses tools like HAS-BLED (originally for atrial fibrillation but applied to VTE), VTE-BLEED, and RIETE (Registro Informatizado Enfermedad TromboEmbólica). Major bleeding rates on anticoagulation range 1-3% per year, with intracranial hemorrhage 0.2-0.5% per year. Patient factors increasing bleeding risk: age >75, prior bleeding, active cancer, renal impairment, hepatic dysfunction, anemia, antiplatelet co-therapy, frequent falls, alcoholism, uncontrolled hypertension. Net clinical benefit (recurrence prevention minus bleeding harm) generally favors continued anticoagulation in most patients with unprovoked PE if bleeding risk is not high.
Anticoagulant choice and dosing: direct oral anticoagulants (DOACs) are first-line for most patients per ACCP and ESC guidelines—apixaban 10 mg twice daily for 7 days then 5 mg twice daily (or 2.5 mg twice daily for extended treatment after 6 months), rivaroxaban 15 mg twice daily for 21 days then 20 mg daily (or 10 mg daily for extended treatment), dabigatran 150 mg twice daily after parenteral anticoagulation for 5-10 days, edoxaban 60 mg daily after parenteral anticoagulation; warfarin (target INR 2-3) remains preferred for mechanical heart valves, antiphospholipid syndrome (especially high-risk profile—triple positive, lupus anticoagulant), severe renal impairment (creatinine clearance <15-30 depending on agent), pregnancy (warfarin in second trimester after lupus anticoagulant), or contraindications/intolerance to DOACs. Low-molecular-weight heparin (enoxaparin, dalteparin) for cancer-associated thrombosis was historic standard; DOACs (apixaban, rivaroxaban, edoxaban) now non-inferior to LMWH in major trials and increasingly first-line, with caution in GI/genitourinary cancers (higher bleeding with DOACs in these). Duration decisions: provoked by major transient—3 months; cancer-associated—at least 6 months and continue while cancer active; unprovoked first PE—at least 3 months, then consider extended/indefinite with shared decision-making (individual recurrence and bleeding risk, patient preference); recurrent unprovoked—indefinite. Reduced-intensity extended therapy (apixaban 2.5 mg twice daily, rivaroxaban 10 mg daily) reduces bleeding while maintaining efficacy compared with full-dose. Periodic reassessment of risk-benefit annually. Specialty considerations: chronic thromboembolic pulmonary hypertension (CTEPH—lifetime anticoagulation, evaluate for pulmonary thromboendarterectomy or balloon pulmonary angioplasty), cancer treatment changes, surgery requiring temporary discontinuation (bridging usually unnecessary with DOACs).