Yesterday marked the two-month anniversary of the availability of the novel blood-thinner dabigatran (Pradaxa). It was approved for the use of preventing stroke in patients with non-valvular AF, but it has quickly taken on the inaccurate moniker of “the warfarin-substitute.”
Here’s the thinking: If stroke prevention in AF is accomplished by thinning the blood, and dabigatran is a blood thinner proven superior to warfarin, then it follows that it could be used for any warfarin indication. Things like clot prevention for mechanical heart valves, clots in the deep veins of the leg or lung, and inherited clotting disorders of the blood (ie…Factor V Leiden.), just to name four of the many other uses of warfarin.
We will see about the efficacy of dabigatran in these “other (warfarin) uses” in the future. But for now, there are simpler and more clinically relevant questions that need answers.
One is: Can dabigatran replace warfarin before and after cardioversion?
Many patients with AF require the procedure, cardioversion—shocking the heart back to regular rhythm. To date, thinning the blood with warfarin before and after the shock is mandated. And, unlike dabigatran, the level of blood-thinning with warfarin can be easily quantified—by measuring the INR level. (An INR of greater than 2.0 is an adequate blood-thinning effect.)
In the largest cardioversion study to date and the first to evaluate dabigatran in the setting of cardioversion, the RE-LY investigators found that when they looked back at the 1270 patients who underwent cardioversion in the 18,000 patient-strong RE-LY trial, “the frequencies of stroke and major bleeding within 30 days of cardioversion on the 2 doses of dabigatran were low and comparable to those on warfarin.” Additionally they showed that the incidence of clots in the left atrial appendage (as defined by transesophageal echo or TEE ) were also low.
And they concluded: “dabigatran is a reasonable alternative to warfarin in patients requiring cardioversion.”
That’s good, because their findings make sense: if dabigatran was superior to warfarin in preventing strokes in AF, it ought to be effective in preventing strokes before and after shocking the heart out of AF.
The next question that AF doctors will have is whether dabigatran can be safely used before and after AF ablation?
My prediction is that the answer is yes.