The American Society of Hematology (ASH) in 2020 has provided evidence-based recommendations for the management of DVT/PE. Covered here are the recommendations for primary treatment and secondary prevention, various risk components and additional management challenges of venous thromboembolism.

Primary treatment

Primary therapy corresponds to the minimum period of time an individual must undergo systemic anticoagulation for the management of early venous thromboembolism (VTE) until discontinuing anticoagulation or transitioning to a long-term anticoagulation protocol to avoid recurrence of VTE (secondary prevention).

The ASH recommendation panel recommends choosing a reduced period of anticoagulation for primary care (3 to 6 months) over a longer course of anticoagulation for primary treatment (6 to 12 months) for primary treatment of patients with DVT and/or PE, whether triggered by a temporary risk factor or by a chronic risk factor, or unprovoked.

Transient risk factors (risk factors that resolve after they have provoked VTE)

Major transient risk factors (occur within 3 months of VTE diagnosis):  

• Cesarean section  
• Surgery with general anaesthesia for ≥30 minutes  
• Confined to bed in hospital for ≥3 days with an acute illness

Minor transient risk factors (occur within 2 months of VTE diagnosis):  

• Confined to bed out of hospital for ≥3 days with an acute illness
• Pregnancy and puerperium   
• Leg injury associated with decreased mobility for ≥3 days
• Surgery with general anaesthesia for <30 minutes
• Oestrogen therapy (e.g. oral contraceptives, hormone replacement therapy)
• Admission to hospital for <3 days with an acute illness

Chronic (persistent) risk factors (risk factors that persist after the development of VTE)

• Chronic infections  
• Autoimmune disorders (eg, antiphospholipid syndrome, rheumatoid arthritis)
• Inflammatory bowel disease  
• Active cancer (e.g. ongoing chemotherapy; recurrent or progressive disease)  
• Post completion of primary care, many patients with DVT and/or PE induced by transient risk factors will discontinue anticoagulant therapy; in comparison, several patients with chronic risk factors-induced DVT and/or PE, and also patients with unprovoked DVT and/or PE, can proceed with anticoagulant therapy indefinitely following completion of primary treatment for secondary prevention
• For chosen patients with a persistent risk factor that is supposed to change over time (e.g. increased mobility with rehabilitation), a prolonged period of anticoagulation for the main care process (e.g. 6 to 12 months) may be warranted

Secondary prevention

In patients with unprovoked DVT and/or PE, the ASH guidance panel proposes against regular use of prognostic ratings, D-dimer monitoring or ultrasound to diagnose residual venous thrombosis to control the length of anticoagulation. The ASH recommendation panel recommends:

1. Prolonged antithrombotic therapy over discontinuation of anticoagulation following completion of primary care for patients with DVT and/or PE caused by a chronic risk factor.
2. Prolonged antithrombotic treatment over the termination of anticoagulation following completion of primary therapy for patients with unprovoked DVT and/or PE except patients having a high risk of bleeding problems.
3. Choosing anticoagulation over aspirin for individuals with DVT and/or PE that have finished primary care and may proceed to undergo secondary prevention.
4. Use of VKA therapy as secondary prevention keeping an international normalised ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with DVT and/or PE that have undergone primary care.

The ASH recommendation panel recommends using a normal dose of DOAC or a lower dose of DOAC for patients with DVT and/or PE who have finished primary care and will proceed with DOAC for secondary prevention. DOAC - rivaroxaban, 10 mg daily, or apixaban, 2.5 mg twice daily.

Treatment of recurrent events

The ASH guidance panel recommends:

1. Using low-molecular - weight heparin (LMWH) over DOAC therapy for patients with breakthrough DVT and/or PE during therapeutic VKA therapy. In order to identify possible causal factors, patients who present with a new VTE case during therapeutic VKA therapy should be further studied. This advice should not extend to patients who, in the case of inadequate INR management, experience breakthrough VTE where a DOAC might be a appropriate alternative.
2. Prolonged antithrombotic therapy to anticoagulation following completion of primary care for patients who acquire DVT and/or PE caused by a temporary risk factor and have a background of prior unprovoked VTE or VTE caused by a chronic risk factor.
3. Avoiding anticoagulation after completion of primary care over prolonged antithrombotic therapy for patients who develop DVT and/or PE induced by a temporary risk factor and have a history of a previous VTE also induced by a transient risk factor.
4. Prolonged antithrombotic therapy for patients with chronic unprovoked DVT and/or PE to ceasing anticoagulation after completion of primary care.

Additional management issues

• The ASH recommendation panel advises halting aspirin over maintaining it for the length of anticoagulation treatment for patients with DVT and/or PE with stable cardiovascular disease (CVD) who are starting anticoagulation who were previously taking aspirin for cardiovascular risk improvement.
• The ASH advisory panel recommends that compression stockings are not routinely used by patients with DVT with or without an elevated chance of PTS.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Monish S Raut is a Consultant in Cardiothoracic Vascular Anaesthesiology. His area of expertise is perioperative management and echocardiography with numerous publications in various national and international indexed journals.