The human heart pushes blood out through the body to all the organs by beating rhythmically. When that rhythm falters, as it does in the condition termed atrial fibrillation, blood is still pumped but less effectively.
Why Is A-Fib So Risky?
These rapid and weak contractions of the upper chambers of the heart can allow some of the blood that would normally have been pumped away to hang around in the heart, possibly long enough to form a clot. If such a clot is then pumped out into circulation, it can lodge in the brain, causing a stroke.
The exact size of the clot and the location where it lodges may determine how much damage is caused. The speed of receiving care, including anti-clotting medication, can also have an impact on stroke damage.
Preventing Blood Clots:
That is why most people with a-fib, or atrial fibrillation, are prescribed a medication to prevent clotting. The first and for many years the only one that was used was warfarin (Coumadin). Although warfarin is a very useful drug, it can be difficult to manage because it interacts with foods and other medicines that can alter its effectiveness. Usually people on warfarin need to have their INR (international normalized ratio, a measure of coagulation) measured on a regular basis, and the dose may need to be adjusted.
The appeal of the newer medications is that they don’t have dosage adjustments and there are no routine measurements of how well they are working. Dabigatran (Pradaxa), rivaroxaban (Xarelto) and apixaban (Eliquis) are all prescribed for this purpose. Although they don’t interact with foods as warfarin does, they are all quite pricey and do not have easily made dose adjustments. Until quite recently, none could be reversed with another drug. That is in contrast to warfarin, which can be reversed with vitamin K in an emergency.
Q. My last visit to the cardiologist indicated that I have atrial fibrillation again in spite of the Multaq that I am taking. The doctor said to keep taking one aspirin at night, stop taking Multaq and take Pradaxa twice a day. According to him, it’s better than Coumadin.
He was adamant that Pradaxa has an antidote, though I’d always heard that there is not one. What is the story on this?
A. Until this fall, there was no antidote to dabigatran (Pradaxa). In October, the FDA approved Praxbind to reverse the anticoagulant effect of Pradaxa in emergencies.
The most serious side effect of Pradaxa is uncontrollable bleeding, so doctors will no doubt find it helpful to have a compound that can reverse the effects of Pradaxa within minutes (New England Journal of Medicine, Aug. 6, 2015).