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HM12 SESSION ANALYSIS: Unanswered Questions in Antithrombotic Therapy


 

Daniel Brotman, MD, FACP, FHM, of Johns Hopkins Hospital in Baltimore, addressed questions all hospitalists wonder about:

1. Is warfarin still the best anticoagulant in afib? 2. Should DVT prevention extend beyond hospitalization? 3. What is the best evidence for LMWH bridging in valve patients? 4. When should anticoagulation be started in stroke patients with afib?

Warfarin, Dr. Brotman explained, has many disadvantages, and new oral anticoagulants (dabigatran, apixaban, rivaoxaban) offer many advantages with lower side-effect profiles. All of the new agents appear to have either better efficacy or trend toward better efficacy, none require monitoring, and all have lower rate of ICH.

Prices are higher for new agents, but are competitive with other drugs currently on market for other diseases. Use dabigatran with caution in patients with renal failure, and realize that there is no antidote for any of these drugs. Dabigatran is acidic and causes GI upset, thus a higher rate of GI bleeding. Stop any of these 5 days prior to planned proceduers; longer if patients are at high risk of bleeding.

Evidence from RCTs in hospitalized surgical patients suggest that VTE prophylaxis should be continued in patients undergoing hip surgery and surgery for abdominal or pelvic malignancy. Patients admitted for acute medical illness do not benefit from VTE prophylaxis beyond acute hospitlaization, even if immobilized, unless they have solid tumors with additional risk factors (hormone use, prior VTE, etc.) and are at low risk for bleeding. Chronically immobilized patients do not benefit from VTE prophylaxis beyond the acute hospitalization.

Bridging-aortic valves have an equivalent CHAD2 score of about 2, so there really is no need to bridge pre-op. Mitral valves have a CHADS2 score of about 4-5, so they always need to be bridged. No head-to-head trials of bridging with LMWH exist, but it's still worth considering if no contraindications because it is much more cost-effective than inpatient admission for IV UFH.

Oral anticoag can be started within 1-2 weeks of stroke onset. The larger the stroke, the greater the risk of hemorrhagic transformation with early anticoagulation, so the smaller the stroke, the safer to start early. VTE prophylaxis important regardless.

Key Takeaways:

  • We'll be using the new oral anticoagulants in place of warfarin in the coming years, although there is no safe anticoagulant. Be cautious and aware of the side effect profiles of each.
  • Don't sweat VTE prophylaxis in chronically immobilized patients unless they are acutely hospitalized.
  • VTE prophylaxis is critical in stroke patients, but the larger the stroke in afib patients, the longer the wait to start oral anticoagulation.

Dr. Foxley is medical director of Inpatient Management, Inc., at the The Nebraska Medical Center Hospitals in Omaha

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