February 15th, 2011
Dabigatran for Patients with AFib: Putting the Updated Recs into Practice
CardioExchange welcomes Samuel Zachary Goldhaber, MD, Director of the Venous Thromboembolism Research Group and Medical Co-Director of the Anticoagulation Management Service at Brigham and Women’s Hospital in Boston. He answers practical questions from the CardioExchange editors about newly updated recommendations on the use of dabigatran in patients with atrial fibrillation, issued by the American College of Cardiology Foundation, the American Heart Association, and the Heart Rhythm Society.
Before pursuing elective cardioversion, should a patient be maintained on dabigatran for 3 weeks, or has the optimal duration changed? If the cardioversion succeeds, should the treatment last an additional 3 weeks after the procedure?
The guidelines remain the same for anticoagulation with planned elective cardioversion: 3 weeks of therapeutic anticoagulation before the procedure and at least 4 weeks of therapeutic anticoagulation after sinus rhythm has been achieved (Chest 2008; 133:546S). Dabigatran becomes therapeutic within 2 hours of administration.
For a patient with new-onset atrial fibrillation, does intravenous heparin have any role as a bridge to dabigatran?
When an asymptomatic patient presents with new-onset atrial fibrillation in the office setting, oral anticoagulation with dabigatran can be started without intravenous heparin. If the patient with new-onset atrial fibrillation is symptomatic, cardioversion may need to be performed imminently (if no thrombus is visualized on transesophageal echocardiography). In the symptomatic patient, there are two options:
- Begin therapy with intravenous heparin. (Cardioversion has not been extensively studied using dabigatran alone in patients with new-onset atrial fibrillation.)
- Begin therapy with dabigatran but without using intravenous heparin. (In the largest cardioversion experience to date, the stroke rate was low in dabigatran recipients, especially if they had been “cleared” first by transesophageal echocardiography; Circulation 2011; 123:131.)
How should a patient be transitioned on and off dabigatran from other antithrombotic agents (e.g., warfarin, enoxaparin, dalteparin, heparin)?
For patients switching from warfarin to dabigatran, give the first dose of dabigatran after the INR has declined to less than 2.0. In practice, this usually means withholding one or two doses of warfarin. For patients receiving parenteral subcutaneous anticoagulation, give the first dose of dabigatran just before the next scheduled injection of parenteral anticoagulation. For patients receiving intravenous heparin, give the first dose of dabigatran about 2 hours after discontinuing intravenous heparin.
If the patient experiences a bleeding complication while on dabigatran, is an antidote available?
There is no specific antidote for dabigatran-related bleeding. General supportive care and “tincture of time” usually work. In extreme circumstances, when confronted with a major, life-threatening hemorrhage, consider using recombinant factor VIIa or emergency hemodialysis.
If a patient has recurrent thromboembolic events while on dabigatran, what test should be performed to monitor the drug’s efficacy? Should a change in treatment be considered?
There is no clinically available test (such as INR, aPTT, or anti-factor Xa level) to monitor dabigatran’s efficacy. If a patient suffers a recurrent thromboembolic event, take a careful history to determine whether one or more doses of dabigatran were omitted. Dabigatran has a short half-life. If medication adherence was perfect, consider switching to another anticoagulation regimen.
For more of our coverage on dabigatran, check out the Dabigatran Resource Round-Up.