Monday, November 7, 2011

New Drugs to Prevent Strokes Associated w/Atrial Fibrillation

Besides the loss of energy & sense of well being resulting from atrial fibrillation, one of the major issues is thromboembolism, specifically to the brain, where it's then known as a stroke.  Over the years, study after study has demonstrated the benefit of taking warfarin, a blood "thinner", to prevent said strokes (via vitamin K-dependent coagulation factors, eg II, VII, IX, X & proteins C & S).

But just like Goldilocks, you need to get it just right, not too thin, but certainly, not too thick, either.  If your blood gets too thin, your risk for serious bleeding increases rather significantly, in which case your risk for a thromboembolic stroke (think clogged pipe) changes to a hemorrhagic one (think burst pipe).  On the other hand, if you forget to take your warfarin or eat certain foods (dark leafy greens) or take certain supplements (vitamin K) that impede its efficacy, then your blood thickens and returns to its normal status of clotting such that you are no longer protected from said clots & strokes.

As you can see, it's not an easy tightrope to walk consistently.  Worse, you have to take time out at least once a month to get your blood checked (for PT/INR) to be sure you're on the right dose (and we then need to (re)adjust your warfarin dose according to your INR in order to help you reach your goal).  What a pain (for both of us)!  Not to mention the additional cost of lab testing . . .

Well, last year, the FDA approved the use of Pradaxa (dabigatran), an oral anticoagulant (direct thrombin inhibitor), to reduce the risk for stroke in patients with atrial fibrillation.  The upside?  No need for periodic lab testing as there's only one dose!  The downside?  It's expensive!  Worse, if you do bleed, there's no way to stop it and purposefully thicken your blood (at least we can do this if you're bleeding from too much warfarin).

This past week, the FDA approved the use of Xarelto (rivaroxaban), another oral anticoagulant that works through a different pathway (factor Xa inhibitor) to prevent strokes in patients with atrial fibrillation.  The upside?  Again, no need for periodic lab testing as there's only one dose!  The downside?  It's expensive!  And just like with Pradaxa, there's no way to stop the bleeding if you're so unlucky.

From no choice to an abundance of choices!  But which drug do you choose?  For most of us, that question will really be answered by our insurance company who will most likely base the decision upon overall cost, assuming similar efficacy.  In the meantime, consider calculating your risk for stroke due to atrial fibrillation and then compare it your risk of bleeding out from warfarin.  The former should exceed the latter if you're going to take some anticoagulant for the rest of your life.  Then chat w/your family doc and discuss whether there's any benefit for you to consider one of these two newer options.

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