From the Guidelines
Anticoagulation therapy, specifically low-dose aspirin, is recommended for patients with polycythemia vera (PV) to reduce the risk of thrombotic events, and should be used in conjunction with cytoreductive therapy to maintain hematocrit below 45%. The use of anticoagulation in PV is supported by studies such as the European Collaboration on Low-dose Aspirin in Polycythaemia Vera (ECLAP) study, which showed that low-dose aspirin significantly reduced the risk of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and major venous thromboembolism 1.
Key Considerations
- The optimal target hematocrit level for reducing vascular events is below 45%, as shown in the CYTO-PV study 1.
- Low-dose aspirin (81-100 mg daily) is the first-line anticoagulant for most PV patients, as it decreases the risk of arterial and venous thrombosis without significantly increasing bleeding risk.
- For patients with a history of thrombosis or additional risk factors (age >60, prior thrombotic events), more intensive anticoagulation may be needed, such as direct oral anticoagulants (DOACs) like apixaban or rivaroxaban, or warfarin with a target INR of 2-3.
- Cytoreductive therapy, such as hydroxyurea or phlebotomy, should be used to maintain hematocrit below 45% and reduce the risk of thrombotic events.
Monitoring and Adjustments
- Regular monitoring of blood counts is essential to adjust therapy based on thrombotic and bleeding risk.
- Anticoagulation should be temporarily suspended during periods of thrombocytopenia (platelets <50,000/μL) or active bleeding.
- The use of cytoreductive drugs, such as hydroxyurea, should be individualized based on patient-specific variables, including age and other risk factors 1.
Treatment Approach
- A comprehensive treatment approach for PV should include management of cardiovascular risk factors, aspirin for vascular symptoms, phlebotomy to maintain hematocrit below 45%, and cytoreductive therapy with hydroxyurea or interferons based on age and other patient-specific variables 1.
From the Research
Polycythemia and Anticoagulation
- Polycythemia vera (PV) is a myeloproliferative neoplasm characterized by an increased red blood cell mass and increased risk of thrombosis 2.
- Thromboembolic events and cardiovascular disease are the most prevalent complications in patients with PV, and are the major cause of morbidity and mortality in this population 3.
- The goal of therapy is to reduce the risk of thrombosis by controlling hematocrit to <45%, a target associated with reduced rates of cardiovascular death and major thrombosis 3.
Anticoagulation Therapy
- Low-dose aspirin is often used to reduce thrombotic risk in patients with PV, and is associated with a statistically non-significant reduction in the risk of fatal thrombotic events and all-cause mortality, without an increased risk of major bleeding 4.
- Oral anticoagulants (OA) may be used as secondary prophylaxis of thrombosis in patients with PV, but meticulous control of anticoagulant therapy is critical to prevent recurrent thromboembolic events 5.
- Nonvitamin K antagonist oral anticoagulants (NOACs) may be effective and safe as secondary prevention of venous thromboembolism (VTE) in patients with myeloproliferative neoplasms, including PV 6.
Risk Factors and Treatment
- Important risk factors for thrombosis in patients with PV include age (≥60 years old) and a history of thrombosis, as well as elevated hematocrit and leukocytosis 3.
- Patients with PV who are at higher risk of thrombosis may benefit from cytoreductive therapy with hydroxyurea or interferon to lower thrombosis risk and decrease symptoms 2.
- Ruxolitinib is a Janus kinase inhibitor that can alleviate pruritus and decrease splenomegaly in patients who are intolerant of or resistant to hydroxyurea 2.