My most likely major problem. My score on the scale they use is "3."
Preventing Stroke In Atrial FibrillationWhen Is Anticoagulation Needed?By Richard N. Fogoros, M.D., About.com Guide
Updated November 21, 2011
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The most dreaded complication of atrial fibrillation is stroke. In atrial fibrillation, the atria of the heart do not beat effectively, which allows the blood to "pool" within these chambers. ( Read here about the cardiac chambers.) As a result, an atrial thrombus (blood clot) can form. Eventually, the atrial thrombus can embolize -- that is, it can break loose and travel through the arteries. All too often, this embolus will lodge in the brain, and the result is a stroke.
So if you have atrial fibrillation, your doctor should do a formal estimate of your risk of stroke, and if that risk is high enough, you should be placed on treatment to prevent blood clots from forming, and thus, to prevent a stroke.
Estimating Your Risk Of Stroke with Atrial Fibrillation Estimating your risk of stroke if you have atrial fibrillation requires taking into account your age, sex, and certain medical conditions you might have. First, if you have significant valvular heart disease in addition to atrial fibrillation, you will need therapy to prevent blood clots, since your risk of stroke is substantially elevated.
If you don't have heart valve disease, your doctor will probably use your CHADS2 score to estimate your risk of stroke. In people with atrial fibrillation, the higher the CHADS2 score, the higher the risk of stroke. The CHADS2 score is calculated as follows:
The total number of points you accumulate for these five risk factors is your CHADS2 score. There is evidence that the CHADS2 score might underestimate the risk of stroke in people a little younger than 75, and in women. So some experts will add a point if you are 65 or above (instead of 75 or above), and also will add a point if you are a woman. But most stick to the original CHADS2 scoring method, as described above.
Here is how how the CHADS2 score reflects the risk of stroke: For every 100 patients with atrial fibrillation whose CHADS score is 0, about 2 per year will have a stroke. For every 100 patients with atrial fibrillation whose CHADS score is 6, about 18 per year will have a stroke. As the CHADS2 score increases from 0 to 6, the yearly risk gradually rises from 2% and 18%. (By way of comparison, for every 100 people over the age of 65 with no atrial fibrillation, about 1 per year will have a stroke.)
In the past, doctors assumed that if they were successful in applying " rhythm control therapy" for atrial fibrillation (that is, treatment aimed at stopping atrial fibrillation and maintaining a normal heart rhythm), the risk of stroke would drop. However, clinical evidence so far has failed to show that rhythm control therapy reduces the risk of stroke. So even if you and your doctor opt for rhythm control therapy, you should still be treated to prevent stroke if your CHADS2 score is high enough. (How the CHADS2 score is used to guide therapy is described below.)
Once your risk of stroke has been estimated, your doctor can make a treatment recommendation for reducing that risk, as follows.
Treatment For Stroke Prevention In Atrial Fibrillation There are two general types of treatment to reduce the risk of stroke in atrial fibrillation -- anticoagulation therapy (with drugs like Coumadin, which inhibit the blood's clotting factors), or aspirin therapy (which reduces the "stickiness" of blood platelets). In atrial fibrillation, anticoagulation therapy is more effective than aspirin, but carries a higher risk of bleeding complications. Treatment with Coumadin reduces the risk of stroke in atrial fibrillation by about 66%, while treatment with aspirin reduces the risk by only around 25%. In terms of side effects, the risk that Coumadin will cause a major bleeding complication varies quite a bit, depending on the patient's medical condition and the care with which Coumadin dose is regulated, but generally that risk is less than 1 - 2% per year. The risk with aspirin is somewhat less than that.
Based upon these relative benefits and risks of treatment, most experts agree that treatment to prevent stroke should be used in patients whose annual risk of stroke is estimated to be higher than 2%, that is, for CHADS2 scores higher than 0.
For a CHADS2 score of 0, neither anticoagulation treatment nor aspirin therapy is generally recommended.
For a CHADS2 score of 1, most experts now recommend anticoagulation treatment, but some believe that aspirin therapy may be an acceptable choice. So if your CHADS2 score is 1, you and your doctor will need to discuss the pros and cons of both of these treatment options.
For a CHADS2 score of 2 or higher, anticoagulation therapy with Coumadin or a similar drug is strongly recommended.
The Newer Anticoagulation Drugs Until recently, Coumadin was the only oral anticoagulant drug available for chronic use. Using Coumadin correctly is difficult for both the doctor and patient -- getting the correct dose (so that the blood is adequately "thin," but not too thin) is often difficult and time-consuming, and requires numerous blood tests. Once the right dose is found, periodic blood tests are still required to use the drug safely, since the optimal dose of Coumadin tends to change over time. In the last few years, several new anticoagulation drugs have been developed, including dabigatran, rivaroxaban, and apixaban. These drugs all have the advantage, compared to Coumadin, of requiring a fixed daily dose, and so the need for frequent blood tests and dosage adjustments is eliminated. And clinical studies have demonstrated these newer drugs to be at least as effective and as safe as Coumadin.
Because finding a safe and effective dose of the newer drugs is neither difficult nor inconvenient, most doctors now prefer to use one of the newer drugs over Coumadin. Currently, dabigatran is used most commonly, because it was the first "Coumadin substitute" approved.
However, there are people in whom Coumadin is still the preferred option. Coumadin remains a good choice if you are taking Coumadin already, and have been completely stabilized on the drug; or if you would rather not take pills twice per day (which is required for dabigatran and apixaban); or if you cannot afford the presently high cost of the newer drugs.
Summary Stroke is the most feared, and unfortunately the most common, major complication of atrial fibrillation. So lowering your risk of stroke is something you and your doctor must take very seriously. Fortunately, if you and your doctor approach the problem systematically -- estimating your risk, and treating accordingly -- your odds of avoiding this dreaded problem will be greatly improved. |
