The Role of Blood Thinners in Atrial Fibrillation

Patient Expert

When the cardiologist broke the news that I was experiencing atrial fibrillation, and after the initial surprise and dismay, the first concern I had -- and apparently the first concern most of us who are diagnosed with this common heart arrhythmia have -- was about blood thinners.

Oh no, I thought. I have to take Coumadin.

I had no idea what that was going to entail, but I knew it wasn't good.   As it turned out, I was right. I had to take this medication at the same time every day and be sure to follow some dietary guidelines such as watching my consumption of spinach and dark greens Apparently these thin your blood with Vitamin K.

(It isn't so much eating these foods, as keeping your consumption of them at the same amounts so there are not any sudden changes in your intake.)

I had to be aware of the possibility that I could bleed more easily and thought about my normal activities in a different way. I was not a rock climber or a skier  nor was a really athletic (walking was my favorite sport, with a little golf)  so these were not big losses for me, but a nosebleed could turn into a problem, and so could a cut, so I had to become more aware.

The most intrusive and the most important part of taking Coumadin (or its generic equivalent, Warfarin) were the regular lab visits to check something called the International Normal Ratio (INR).   Your blood numbers need to fall between 2 and 3. It's a very narrow range, and it's taken very seriously. If you drop below 2, your blood is too "thick" (your blood is not actually thick or thin - we will discuss this later in this article), and if you rise above 3 your blood is too "thin."   Either situation is not good for someone in atrial fibrillation and needs to be addressed.

When I began getting regular blood tests, I learned that if I stayed between 2-3 I could skip a week or even two weeks of checking in. The longer I had my perfect 2.3 for example, the longer I could stay away from the lab.   This was always a treat, because the lab that did my testing was a 35 minute drive in each direction, plus the wait to get in could be about a half hour.

I was on Warfarin for three months before my cardiologist performed a cardioversion and my heart converted immediately to NSR (Normal Sinus Rhythm) and stayed there. I did not require anti-arrhythmic medications, which can cause unpleasant side effects for some.   I was lucky, because only 20-25% of afib sufferers are able to get a lasting conversion from a cardioversion. But that didn't get me off of Warfarin. It would be three years, until  after my open heart mitral valve repair surgery, when my surgeon finally gave the all clear for me.

Why, patients ask, must my blood be managed?   What happens to my blood during atrial fibrillation?   John Doherty, MD , Professor of Medicine at Thomas Jefferson University School of Medicine in Philadelphia and member of the American College of Cardiology's Anticoagulation Initiative calls what happens in afib the "clotting cascade."   It is, he says, a "series of events by which different compounds are generated and result in blood coagulation (clotting)." The irregular rhythm allows blood to pool in the heart, which results in my chance for clotting.

Coagulation or clotting, of course, can lead to dangerous or fatal strokes, which are many times more likely to occur in a patient with atrial fibrillation.

In the last few years, three new drugs have joined the old mainstay Coumadin/Warfarin to target that "cascade" and help prevent strokes in afib patients.

Pradaxa (dabigatran) was approved by the FDA in October 2010 for prevention of stroke and blood clots in afib patients.

Xarelto (rivaroxaban) came online in November 2011 for stroke prevention from afib after initial approval to lower risk of blood clots after hip and knee replacements.

And Eliquis (apixaban) joined the lineup in December 2012 to lower risk of stroke and dangerous blood clots.

In my following of articles on atrial fibrillation and blood thinners, we'll further explore the drugs available for regular treatment, how they work and other   ways to work with the effects of atrial fibrillation. We'll also take a look at the   anticoagulative drugs used in emergency situations for many, such as Heparin and Lovenox, both of which I have had in hospital situations.