Management of VTE: 10 New Recommendations
Dr. Tafreshi is professor and director of cardiology pharmacy practice residency at Midwestern University College of Pharmacy-Glendale (MWU-CPG), Glendale, Ariz. At the time of submission of this article, Dr. Patterson was a senior pharmacy student at MWU-CPG.
Although a thrombus may formin any part of the venous circulation,the majority of thrombiform in the lower extremities.1-3 The formationof such thrombi is known asvenous thromboembolism (VTE). Once athrombus is formed, it may lyse spontaneously,obstruct venous circulation, orembolize.1-3 When the venous circulationin lower extremities is obstructed by athrombus, the condition is known asdeep vein thrombosis (DVT). A thrombusthat leaves the peripheral veins andlodges in the pulmonary artery or 1 of itsbranches is known as a pulmonaryembolism (PE).1-3
Three primary components (Virchow?striad) play a role in the development of athrombus: venous stasis, vascular injury,and hypercoagulability.1-3 Venous stasisresults from damage to venous valves,vessel obstruction, prolonged periods ofimmobility, or increased blood viscosity.Vascular injury may result from majororthopedic surgery, trauma, or indwellingvenous catheters. Hypercoagulablestates include malignancy, activated proteinC resistance, or deficiency of proteinC, protein S, or antithrombin.
A long-term complication of DVT ispostthrombotic syndrome. This conditionis caused by damage to venous valves bya thrombus. It may produce lower-extremityswelling, pain, tenderness, skindiscoloration, and ulceration.
Symptoms of PE may include dyspnea,tachypnea, chest pain, tachycardia, palpitations,hemoptysis, cough, and diaphoresis.Severe cases will present withcardiovascular collapse characterized bycyanosis, shock, and oliguria. Symptomsof DVT may include unilateral leg swelling,pain, tenderness, erythema, and warmth.All these symptoms are considered to benonspecific for PE and DVT.
Radiographic contrast studies are themost accurate and reliable method forthe diagnosis of VTE. Ultrasonographymay be preferred for the initial diagnosisof VTE because it is a noninvasive test. PEmay be diagnosed by using either a ventilation-perfusion (V/Q) scan or spiralcomputed tomography. Chest x-rays alsomay assist in the diagnosis of PE. Chest x-raysmay be normal or may show awedge-shaped consolidation in the middleand lower lobes, which may be suggestiveof a pulmonary infarction.Electrocardiograms may be abnormal in85% of patients with acute PE. Some ofthe most frequent abnormalities mayinclude sinus tachycardia, new-onset atrialfibrillation, and ST segment changes.
There are several risk factors for thedevelopment of VTE (Table 14).
A prediction rubric known as the Wellsprediction rules can be used to predictthe probability of DVT and PE. The resultmay help determine which diagnostictests may be needed, based on clinicalpresentation (Tables 2 and 3).5,6
Recently, the American College ofPhysicians and the American Academyof Family Physicians published detailedrecommendations for the diagnosisand management of VTE.7,8 The followingare selected excerpts from the recommendationsdescribed in theseguidelines.Diagnosis of VTE7
Recommendation 1Validated clinical prediction rulesshould be used to estimate pretestprobability of VTE, both DVT and PE,and as the basis of interpretation ofsubsequent tests.
Recommendation 2In appropriately selected patientswith low pretest probability of DVTor PE, obtaining a high-sensitivity D-dimerassay is a reasonable option.If negative, it indicates a low likelihoodof VTE.
Recommendation 3Ultrasound is recommended forpatients with intermediate-to-highpretest probability of DVT in thelower extremities.
Recommendation 4Patients with intermediate or highpretest probability of PE require diagnosticimaging studies.Management of VTE8
Recommendation 1Low-molecular-weight heparin (LMWH)rather than unfractionated heparinshould be used whenever possible for theinitial inpatient treatment of DVT. Eitherunfractionated heparin or LMWH isappropriate for the initial treatment of PE.
Recommendation 2Outpatient treatment of DVT, and possiblyPE, with LMWH is safe and cost-effectivefor carefully selected patients. Itshould be considered if the required supportservices are in place.
Recommendation 3Compression stockings should beused routinely to prevent post-thromboticsyndrome, beginning within 1 month ofdiagnosis of proximal DVT and continuingfor a minimum of 1 year after diagnosis.
Recommendation 4There is insufficient evidence to makespecific recommendations for types ofanticoagulation management of VTE inpregnant women.
Recommendation 5Anticoagulation should be maintainedfor 3 to 6 months for VTE secondary totransient risk factors and for more than12 months for recurrent VTE. Althoughthe appropriate duration of anticoagulationfor idiopathic or recurrent VTE is notknown definitely, evidence exists of substantialbenefit from extended-durationtherapy.
Recommendation 6LMWH is safe and efficacious for thelong-term treatment of VTE in selectedpatients (and may be preferable forpatients with cancer).References
1. Barreiro TJ. In: Domino, FJ, ed. The 5-Minute Clinical Consult. Philadelphia, Pa: Lippincott Williams & Wilkins; 2007.
2. Ferri FF. Ferri?s Clinical Advisor. 9th ed. Philadelphia, Pa: Mosby; 2007.
3. Haines ST, Zeolla M, Witt DM. In: Dipiro JT, ed. Pharmacotherapy. 6th ed. New York, NY: McGraw-Hill; 2005.
4. Geerts WH, Pineo GF, Heit JA, et al. Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004;126(3 suppl):338S-400S.
5. Wells PS, Anderson DR, Bormanis J, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 2002;350:1795-1798.
6. Chagnon I, Bounameaux H, Aujesky D, et al. Comparison of two clinical prediction rules and implicit assessment among patients with suspected pulmonary embolism. Am J Med. 2002;113:269-275.
7. Qaseem A, Snow V, Barry P, et al. Current diagnosis of venous thromboembolism in primary care: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med. 2007;5:57-62.
8. Snow V, Qaseem A, Barry P, et al. Management of venous thromboembolism: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians. Ann Intern Med. 2007;146:204-210.