Do You Need Coumadin: Your CHADS2 Score
December 30, 2008 8:21 AM CT
Whether or not you should be on Coumadin or warfarin is a continuing controversy among those with atrial fibrillation. How do you know your risk of stroke and whether or not you should be taking Coumadin? Your doctor will assess your CHADS2 score to determine whether or not you should be on Coumadin.
In this special video segment, Dr. Manish Shah, Electrophysiologist at Washington Hospital Center in Washington, DC, answered our questions about the CHADS2 system.
View the video: Do You Need Coumadin: Your CHADS2 Score
Also watch Part 2 of our Coumadin Series: Coumadin Replacements in Trial – Dabigatran and Rivaroxaban
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About Dr. Shah: Dr. Manish H. Shah is Associate Director of Cardiac Arrhythmia Research at the Washington Hospital Center in Washington, D.C., and Assistant Professor of Medicine at Georgetown University School of Medicine. Dr. Shah comes to Washington Hospital Center from the Johns Hopkins Hospital in Baltimore where he completed a five-year fellowship in Clinical Cardiology and Clinical Cardiac Electrophysiology. He served as Hopkins’ Chief EP fellow for 2007-2008. Prior to his training in Baltimore, Dr. Shah completed an internship and residency at the Harvard Medical School Brigham and Women’s Hospital in Boston.
Dr. Shah: As you know, when you have atrial fibrillation, as a physician the one thing that we are worried the most about is your risk of stroke. There is a large body of evidence that shows that those patients who have atrial fibrillation as well as certain other risk factors are at higher risk for having a stroke.
One of the commonly used criteria is something we call the CHADS2 Score, which is shown here. The CHADS2 score is just a mnemonic to help us remember the additional risk factors.
Those risk factors would include having heart failure, age greater than 75 years, high blood pressure, high blood sugar or Type II diabetes mellitus, and a prior history of stroke or a TIA.
We know that when you have more of these risk factors in addition to atrial fibrillation your yearly risk of stroke increases. That is best seen in this table where we can see that if you have a CHADS score of zero, your yearly risk of having a stroke is somewhere around two per cent and then with each additional point your risk increases.
As physicians, we try to figure out which medications are appropriate for your particular level of risk.
If you have zero risk factors for having a stroke with atrial fibrillation then it is possible that aspirin therapy alone will be adequate. However, in general, if you have two or more risk factors the national guidelines would say that we should use Coumadin, a blood thinner, to reduce your risk of stroke. The benefit of Coumadin is roughly a two-thirds risk reduction in your yearly stroke risk.
Interviewer: So the CHADS2 risk criteria, what does that mean?
Dr. Shah: CHADS2 is just a mnemonic, and it is a way for physicians to assess your level of risk. There is a point base system so that if you have high blood pressure, diabetes, prior history of stroke, you get a point for each of those. Stroke, you actually get two points. We use that point system to assess what your yearly risk of having a stroke is.
When we look at this table, typically we can see that if your CHADS score is less than one, we typically recommend aspirin therapy only. However, when your CHADS score is greater than two we generally recommend Coumadin. If you are at two it is really up to the physician discretion as to whether or not we put you on aspirin therapy or Coumadin.
Now, many patients who are taking Coumadin for atrial fibrillation to reduce their risk of stroke don’t like taking it. The reason why they don’t like taking it is because there is what’s called a “narrow therapeutic window.” That just basically means that we have to constantly monitor your blood thinness level. That measurement is called an INR and we measure that typically once every two weeks, or once every month when a patient is on a stable dose of Coumadin.
The other problem with Coumadin is that patients do not like to take it because it often takes several days for the blood level to become thin enough. Often it is five to six days of starting with a loading dose of Coumadin before your blood is adequately thinned.
The other problem with Coumadin that patients do not like is that the dose can vary from patient to patient. So, I have some patients that are on 2.5 mg of Coumadin a day and others that are on 15 mg of Coumadin a day. It is almost a trial and error that we have to use to get the right dose of Coumadin to get the right level of blood thinness, that 2.0 to 3.0 INR range.