Anticoagulants for Stroke Prevention in People with Atrial Fibrillation

Atrial fibrillation is the most common type of arrhythmia (irregular heartbeat). Atrial fibrillation occurs when rapid, disorganized electrical impulses cause the two upper chambers of the heart (atria) to fibrillate (quiver) and contract very fast and irregularly. As a consequence of atrial fibrillation, blood pools in the atria and is not pumped completely into the the heart's two lower chambers (ventricles). The pooling of blood in the atrial chambers of the heart significantly increases the risk of formation of blood clots. If a piece of a blood clot breaks off and travels to the brain it can occlude (block) a blood vessel and prevent blood from reaching the affected area of the brain. This condition is known as an ischemic stroke and can cause severe disability including the inability to walk or talk.

In order to reduce the risk of ischemic stroke in people with atrial fibrillation, anticoagulant (blood thinner) medications are often prescribed. The most commonly used blood thinner is warfarin (Coumadin) although aspirin may also sometimes be used. While blood thinners can prevent ischemic stroke in people with atrial fibrillation, paradoxically, they can also cause bleeding into the brain, a condition known as _intracranial hemorrhage.

Unfortunately, doctors don't have a fool-proof method of determining which patients with atrial fibrillation will benefit from blood thinners (prevention of ischemic stroke) and which patients may be harmed by blood thinners (cause an intracranial hemorrhage). Clearly, more research is necessary to more accurately identify those patients who would benefit the most from taking blood thinners as opposed to those who are more likely to be harmed by taking blood thinners.

A study published in 2009 in the Annals of Internal Medicine (Volume 151; pp. 297-305) by a collaborative group of researchers from the Massachusetts General Hospital, the University of California at San Francisco, and Kaiser Permanente of Northern California has contributed significantly to better understanding which patients with atrial fibrillation would benefit most from receiving anticoagulants for stroke prevention. The study population consisted of 13,559 people with atrial fibrillation with a median age of 73 years. Twenty (20) percent of the subjects had no major risk factors for ischemic stroke. The major risk factors for ischemic stroke include older age (75 years or older), previous history of stroke, diabetes, hypertension, and congestive heart failure. This stroke-risk classification system is known as the CHADS2 grading system and is used by doctors as a basis for classifying patients with atrial fibrillation into stroke risk categories (low, intermediate, or high). The researchers followed the clinical course of these 13,559 patients for a median of 6 years. At the time of enrollment into the study, 53% of the subjects were receiving warfarin (Coumadin) as prophylaxis for stroke prevention.

During the follow-up period, the researchers identified a total of 1,092 thromboembolic events (occlusion of a blood vessel by a blood clot) among the study subjects, the overwhelming majority of which (1,017 cases or 93%) were ischemic strokes. Of the patients who experienced a thromboembolic event, 37% were receiving warfarin and 63% were not receiving warfarin. The researchers also identified 299 patients among the study cohort who experienced an intracranial hemorrhage, of which 193 patients (65%) were receiving warfarin.

The major findings of the study can be summarized as follows:

• The greatest benefit of anticoagulation therapy for the prevention of ischemic stroke was observed among patients with a history of ischemic stroke and those in the highest stroke risk category as determined by the CHADS2 stroke-risk grading system.
• In general, the net benefit of receiving warfarin anticoagulation therapy increased with advancing age. Patients with atrial fibrillation in the oldest age group (85 years of age or older) derived more benefit from warfarin prophylaxis than patients in the 75 to 84 year age group, although the benefits of warfarin prophylaxis was apparent in this age group as well.
• This finding strongly suggests that elderly people with atrial fibrillation who are not taking warfarin are at increased risk for ischemic stroke, however, adding warfarin for prevention of ischemic stroke in elderly people does not significantly increase the risk of intracranial hemorrhage.
• Younger people with atrial fibrillation (64 years or younger) who are considered at low risk for developing an ischemic stoke as measured by the CHADS2 stroke-risk grading system, appear to derive little benefit from warfarin prophylaxis and, indeed, adding warfarin may do more harm (intracranial hemorrhage) than good (prevention of ischemic stroke).

In summary, this study has contributed significantly to more clearly identifying which patients with atrial fibrillation will derive the most benefit from warfarin anticoagulation therapy and which patients may be harmed by this treatment. If you have atrial fibrillation, talk to your doctor about the risks and benefits of taking blood thinner medications. In general, older peope and those at highest risk for ischemic stroke as determined the CHADS2 stroke-risk grading system will gain the most from anticoagulation therapy. Blood thinners, however, may not be advantageous, however, and may cause more harm than good in younger patients with atrial fibrillation who are considered to be at low risk for developing an ischemic stroke.

The Medifocus Guidebook on Atrial Fibrillation

If you or someone you love is suffering with Atrial Fibrillation, it's natural to want to know about the causes, symptoms, treatment options, and possible outcomes. By learning as much as possible about your condition, you can become a more effective advocate for yourself, take a more active role in your health, and make informed decisions about your treatment.

That's why you may be interested to learn more about the Medifocus Guidebook on Atrial Fibrillation, the most comprehensive, up-to-date, and trustworthy resource about Atrial Fibrillation available anywhere. Whether you are newly diagnosed or have suffered with the condition for years, this "one-of-a-kind" Guidebook will quickly provide you with the knowledge you need to take more control of your health and make informed decisions about your treatment.

The Guidebook starts out by quickly answering your most fundamental questions about Atrial Fibrillation, including:

• What causes the condition and what are the risk factors?
• What are the predominant signs and symptoms?
• What tests are needed to establish the diagnosis of Atrial Fibrillation?
• What are the standard treatments?
• What are your treatment options if the standard treatments don't work for you?
• What is the most likely expected outcome after treatment has been completed?
• How will the condition affect your lifestyle and your quality of life?
• What are the most important questions to ask your doctor about Atrial Fibrillation?

Providing you with fundamental information about Atrial Fibrillation is a good starting point...BUT the Guidebook doesn't stop just there. At Medifocus we recognize that people suffering with Atrial Fibrillation want more than just basic-level information about the condition. They also want to know about the leading experts in the field, the medical institutions that are conducting breakthrough research, the lessons learned from recently completed clinical trials, and the organizations and support groups that can help them to better cope with the condition.

That's why the Medifocus Guidebook on Atrial Fibrillation is the only resource available that ALSO includes:

• A unique index of leading experts in Atrial Fibrillation in both the U.S. and around the world.
• The hospitals and medical institutions that are conducting breakthrough research on Atrial Fibrillation.
• Recently published medical journal articles about Atrial Fibrillation with hyperlinks to the summaries (abstracts) of the articles, focusing on new treatments under investigation, lessons learned from recent clinical trials, and the latest research advances.
• A comprehensive directory of organizations, support groups, and alternative medicine resources with complete contact information.
• Practical advice and recommendations to help you find doctors with expertise in managing Atrial Fibrillation.

Disclaimer: the authors of this Web site are not medical doctors and are not affiliated with any medical school or organization. The information on this site is not intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health professional prior to starting any new treatment or with any questions you may have regarding a medical condition. Nothing contained in this service is intended to be for medical diagnosis or treatment.

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(This page last updated 1/03/11)