I hope we are right.
Dabigatran (Pradaxa) use in my community has taken off. It’s not just AF-doctors, it’s all doctors, internists and cardiologists alike. Honestly, it’s a little scary.
That’s why I read with great interest anytime other practicing doctors speak about how they use the 4-month-old blood-thinner. Remember, this is not a just a new pill; it’s an entire paradigm shift.
Today, on Cardio-Exchange (an online community of cardiovascular professionals from the NEJM), Dr Samuel Goldhaber, Director of the Venous Thromboembolism Research Group and Medical Co-Director of the Anticoagulation Management Service at Brigham and Women’s Hospital, answered five practical questions about the use of dabigatran.
How should we use dabigatran around the time of cardioversion—a common procedure to terminate AF?
Dr Goldhaber confirmed the established practice that AF patients considered for cardioversion should have their blood thin for three weeks before, and 4 weeks after the shock. That’s the same protocol that we use with warfarin. The reason we do this is to prevent blood clots that might have occurred in the fibrillating atria from dislodging after the shock restores regular atrial squeezing.
Does IV or subcutaneous blood thinners, like heparin or enoxaparin (Lovenox), have any role as a bridge to dabigatran in newly-discovered AF patients?
The answer is no. Unlike warfarin, which takes about three days to thin the blood, Dabigatran begins working in only 60 minutes. This is one of its greatest advantages: patients that require immediate blood-thinning no longer require a shot. Now we can simply have them swallow a pill. Thinning the blood without needles is HUGE!
How should we transition patents off their current blood thinners—usually warfarin—to dabigatran?
When patients stop taking warfarin, the blood begins to thicken in a day or two. Dabigatran thins the blood immediately. Put together, it made sense to me to start dabigatran 24-48 hours after the last warfarin dose. Dr Goldhaber said that’s how he does it as well. Good.
In the event of bleeding, is there an antidote for dabigatran?
No. Dabigatran does not have an antidote. That sounds bad, but the good news is that when dabigatran is stopped the blood thickens in a matter of hours. After four months of dabigatran use, I have yet to see, or hear of a bleed with dabigatran.
What should doctors do if a patient on dabigatran has repeated symptoms that suggest the presence of blood-clots–like stroke?
The absence of a test to measure dabigatran’s effect is one of its most relevant differences with warfarin. With warfarin, measuring the INR allows confirmation that the blood is thin—that the patient is taking the medicine. With dabigatran, the thinness of blood is unknowable. That’s why when patients on dabigatran have a stroke, Dr Goldhaber suggests that we “take a careful history to determine whether one or more doses of dabigatran were omitted.” Only the patient knows whether they are taking the medicine. This personal responsibility thing is also a paradigm shift. One that I find very intriguing.
Thanks to Cardio-Exchange, and Dr Goldhaber for providing such practical information.