Best practices for managing lower-extremity DVT
R. Brad Cook, M.D.
Vascular surgeon, Providence Heart and Vascular Institute
Pacific Vascular Specialists
Published June 2013
Last year the American College of Chest Physicians published its latest guidelines for treating and preventing thrombosis, a body of work 20 years in the making and more than 800 pages long.
Fortunately, abbreviated references are available, and they’re a valuable resource for patient care. They use the ACCP’s grading system, which classifies treatment recommendations based on the balance of benefits and harm (1 = strong, 2 = weak) and the quality of evidence supporting each recommendation (A = high, B = moderate, C = low). A strong recommendation with high-quality evidence, for example, would be designated as 1A; a weak recommendation with low-quality evidence would be graded 2C.
Although the ACCP’s guidelines address all aspects of managing deep vein thrombosis, this article highlights recommendations only for managing lower-extremity DVT in common clinical scenarios.
Treating proximal or iliofemoral DVT
For any patient diagnosed with an acute DVT involving the iliac or femoral veins, the guidelines recommend starting a vitamin K antagonist such as Coumadin at the same time as the parenteral anticoagulation. The patient should continue parenteral anticoagulation for at least five days until the international normalized ratio, or INR, is at the goal range of 2 to 3 or higher for at least 24 hours (grade 1B).
Low-molecular-weight heparin or fondaparinux is recommended over intravenous unfractionated heparin (grade 2C for all comparisons). Once-daily administration is preferred over twice daily.
Initial treatment may take place at home under certain conditions (grade 1B) – if the patient has well-maintained living conditions, strong support from family or friends, phone access and the ability to return to the hospital quickly if needed.
Early mobility is preferred over bed rest (grade 2C). Compression stockings of at least 20 to 30 mmHg will help lower the risk of post-thrombotic syndrome.
Treating distal (calf vein or tibial) DVT
The decision to proceed with anticoagulation versus serial imaging for patients with isolated distal (i.e. infrapopliteal) DVT always has been complex. The ACCP suggests basing the therapy on the severity of the patient’s symptoms and risk factors for thrombus extension.
For patients who have an isolated distal DVT with no severe symptoms or risk factors for extension, the guidelines suggest serial imaging of the deep veins for two weeks before considering an anticoagulant (grade 2C).
Initial coagulation is recommended, however, for patients at risk for thrombus extension or who have severe symptoms attributed to the clot. Anticoagulation management should be the same as for patients with a proximal DVT.
If a patient is being followed by serial imaging, anticoagulation should be started if the follow-up ultrasound shows any thrombus extension, regardless of whether it remains confined to the distal veins (grade 2C) or if it propagates into the proximal veins (grade 1B).
How long to continue anticoagulant therapy?
For patients with a proximal DVT caused by surgery or a transient risk factor, three months of anticoagulation therapy is recommended over a longer (grade 1B) or shorter (grade 1B) period of time. Three months also is the suggested duration for treating an isolated distal DVT. After that, the benefit of extended therapy should be weighed against the bleeding risk.
For patients with a second or unprovoked DVT, however, anticoagulation treatment should last longer than three months. In those cases, the length of therapy depends on the risks of bleeding and recurrent thrombosis.
The role of catheter-directed thrombolysis
Evidence supporting the use of catheter-directed thrombolysis to treat extensive acute proximal DVT is growing, but published studies are not sufficient to offer a strong recommendation for or against the option.
The guidelines recommend anticoagulant therapy alone over catheter-directed thrombolysis (grade 2C). Patients most likely to benefit from these interventions have:
- An extensive, acute iliofemoral DVT
- Symptoms lasting fewer than 14 days
- Good functional status
- Life expectancy of greater than one year
- A low risk of bleeding
In these patients, studies have shown improved mortality and fewer incidents of post-thrombotic syndrome, recurrent DVT and pulmonary embolism. Research has shown an increase in nonfatal bleeding, however. More studies are needed to reach a definitive conclusion.