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Thrombus
The American Society of Hematology (ASH) has released a new set of guidelines for the prevention, diagnosis, and management of venous thromboembolism (VTE).
The new guidelines contain more than 150 individual recommendations, including sections devoted to managing VTE during pregnancy and in pediatric patients.
Guideline highlights cited by some of the writing panel include a high reliance on low-molecular-weight heparin (LMWH) as the preferred treatment for many patients, reliance on the D-dimer test to rule out VTE in patients with a low pretest probability of disease, and reliance on the 4Ts score to identify patients with heparin-induced thrombocytopenia.
An updated set of VTE guidelines were needed because clinicians now have a “greater understanding of risk factors” for VTE as well as having “more options available for treating VTE, including new medications,” Adam C. Cuker, MD, of the University of Pennsylvania in Philadelphia and co-chair of the guideline-writing group, said during a webcast to unveil the new guidelines.
The guidelines, released on November 27, took more than 3 years to develop, an effort that began in 2015.
Prevention
For preventing VTE in hospitalized medical patients, the guidelines recommend initial assessment of the patient’s risk for both VTE and bleeding.
Patients with a high bleeding risk who need VTE prevention should preferentially receive mechanical prophylaxis, either compression stockings or pneumatic sleeves.
But in patients with a high VTE risk and an “acceptable” bleeding risk, prophylaxis with an anticoagulant is preferred over mechanical measures, said Mary Cushman, MD, of the University of Vermont in Burlington and member of the guideline writing group.
For prevention of VTE in medical inpatients, LMWH is preferred over unfractionated heparin because of its once-daily dosing and fewer complications, Dr. Cushman said.
The panel also endorsed LMWH over a direct-acting oral anticoagulant (DOAC), both during hospitalization and following discharge.
The guidelines for prevention in medical patients explicitly “recommended against” using a DOAC “over other treatments” both for hospitalized medical patients and after discharge. The guidelines further recommend against extended prophylaxis after discharge with any other anticoagulant.
Another important take-away from the prevention section is a statement that combining both mechanical and medical prophylaxis is not needed for medical inpatients.
And once patients are discharged, they have no need for compression stockings or aspirin on a long plane trip if their risk for thrombosis is not elevated.
People with a “substantially increased” thrombosis risk “may benefit” from compression stockings or treatment with LMWH, Dr. Cushman said.
Diagnosis
For diagnosis, Wendy Lim, MD, of McMaster University in Hamilton, Ontario, Canada, highlighted the need for first categorizing patients as having a low or high probability for VTE, a judgment that can aid the accuracy of the diagnosis and that helps avoid unnecessary testing.
For patients with low pretest probability, the guidelines recommend the D-dimer test as the best first step. Further testing isn’t needed when the D-dimer is negative, Dr. Lim noted.
The guidelines also recommend using ventilation-perfusion scintigraphy (V/Q scan) for imaging a pulmonary embolism over a CT scan, which uses more radiation. But V/Q scans are not ideal for assessing older patients or patients with lung disease, Dr. Lim cautioned.
Management
Management of VTE should occur, when feasible, through a specialized anticoagulation management service center, which can provide care that is best suited to the complexities of anticoagulation therapy.
But it’s a level of care that many U.S. patients don’t currently receive and, hence, is an area ripe for growth, said Daniel M. Witt, PharmD, of the University of Utah in Salt Lake City.
The guidelines recommend against bridging therapy with LMWH for most patients who need to stop warfarin when undergoing an invasive procedure.
The guidelines also call for “thoughtful” use of anticoagulant reversal agents, and they advise that patients who survive a major bleed while on anticoagulation should often resume the anticoagulant once they are stabilized.
For patients who develop heparin-induced thrombocytopenia, the 4Ts score is the best way to make a more accurate diagnosis and boost the prospects for recovery, according to Dr. Cuker, lead author of a paper on the subject published in Blood.
The guidelines cite several agents now available to treat this common complication, which affects about 1% of the 12 million Americans treated each year with heparin, argatroban, bivalirudin, danaparoid, fondaparinux, apixaban, dabigatran, edoxaban, and rivaroxaban.
ASH has a VTE website with links to detailed information for each of the guideline subcategories: prophylaxis for medical patients, diagnosis, anticoagulation therapy, heparin-induced thrombocytopenia, VTE in pregnancy, and VTE in children.
The website indicates that additional guidelines will soon be released on managing VTE in patients with cancer, in patients with thrombophilia, and for prophylaxis in surgical patients, as well as further information on treatment. A spokesperson for ASH said these additional documents will post sometime in 2019.
At the time of the release, the guidelines panel published the following six articles in the journal Blood Advances that detail the guidelines and their documentation relating to VTE and:
Drs. Cushman, Lim, and Witt reported having no relevant disclosures. Dr. Cuker reported receiving research support from T2 Biosystems.