THE HEART OF THE MATTER
a special program of the National Emergency Medicine Association (NEMA) 

Week: 523.1 Guest: Wayne Clark, M.D. Topic: Warfarin...Stroke Prevention Drug- One Part Host: Steve Girard Producer: Ed Graham

NEMA: We're with Dr. Wayne Clark, the Director of the Oregon Stroke Center in Portland...talking about preventing strokes...and Doctor, you've told me there are basically three ways of preventing strokes in patients who are either predisposed to a stroke or who have had one already, depending upon what type you're trying to prevent....right?

CLARK: For many types of strokes, aspirin is the mainstay of therapy. Just one aspirin a day greatly reduces the risk of having another stroke. However, for other types of stroke, it may turn out that surgery, if there's blockage in the artery in your neck, it may turn out that its surgery that should be done to try to clean that out. And then, finally, in strokes that are from the heart, if its a blood clot that breaks loose in the heart and then goes downstream, for that type of stroke, a strong blood thinner, and Warfarin is that strong blood thinner, is the therapy that's indicated to prevent a stroke in those kind of cases.

NEMA: Explain to me how a heart originated blood clot forms, and how Warfarin helps...

CLARK: When the heart's not working properly, the blood pools in there, sort of like a bend in a river that gets stagnant...the blood is not flowing as well as it should, and a small clot begins to form, a few red cells get stuck together. This enlarges, almost like a snowball rolling down a hill, as the clot gets bigger and bigger, until it can get to be a very large clot, and a piece of that can break loose, and go downstream to the brain. Now, Warfarin is such that it keeps the clot from getting any bigger...it inhibits the body's ability to form a blood clot.

NEMA: Who's at risk of a heart originated clot?...and are they given Warfarin short term...or continuously...?

CLARK: The people who are in an irregular heartbeat, its called atrial fibrillation, people who may have already had a heart attack and therefore, part of their heart's not working, or some people who have a problem with a valve in their heart. Those three types of risk factors are the folks that would be indicated to receive Warfarin. Warfarin, or Cuminin, which is its other name, should be given every day...its not the kind of medicine that you take just once in awhile, when you feel like it, it has to be given every day so it gets the blood at just the right level of thinness, cause if its too low, its not going to be effective, and clots might form...if its too high, its dangerous in that it can cause bleeding, because the blood gets so thin. So you have to have it closely monitored to keep it just at the right level.

NEMA: I understand Warfarin...which is rat poison, in large doses ..has been around since the 40's... has the way its administered changed of late...?

CLARK: Just in the last five years, who should receive it in terms of people who are in the irregular heart rate, atrial fibrillation, that's a very common disease and many patients are in this irregular heart rate. We've gone back and forth in the last few years, one study came out that said...well, no..you don't really need to be on Warfarin, another one came out and said the risks were really pretty high....and it wasn't until a final, large study was done that we really have an understanding now that just about everybody should be on Warfarin if they're in that irregular heart rate.

NEMA: Those at risk for heart originated blood clots can take Warfarin as a way of preventing a stroke... except people who are at high risk of falling and breaking a bone, and people who may have an ulcer ...because of the chance of excessive bleeding because of blood thinning effects of the drug. I'm Steve Girard.