Anticoagulants for atrial fibrillation

Examples

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Brand Name	Chemical Name
Jantoven	warfarin

How It Works

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Anticoagulant medications help prevent the formation of blood clots by increasing the time it takes a blood clot to form. This also prevents an existing clot from getting larger.

Why It Is Used

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Anticoagulants are recommended for all people with atrial fibrillation who are 75 years of age or older and can take anticoagulant medications safely. Anticoagulant medications, such as warfarin, are recommended for anyone who has any high risk factor or more than one moderate risk factor for stroke, regardless of age.

High risk factors for stroke include:

• Previous transient ischemic attack or stroke or other blood clot problems.
• High blood pressure.
• Heart failure or poor left ventricular systolic function.
• Age older than 75.
• Rheumatic mitral valve disease.
• Artificial heart valves.

Moderate risk factors for stroke include:

• Age from 65 to 75.
• Diabetes.
• Coronary artery disease with normal heart function.

Anticoagulants reduce the risk of stroke in anyone with atrial fibrillation. Even after your heart rhythm is under control, you may still take warfarin. Some people go in and out of atrial fibrillation without even knowing it. Taking warfarin can lower your chances of having another blood clot or a stroke.

The use of anticoagulants is recommended for at least 3 weeks before and 1 to 3 months after cardioversion.

Should I take anticoagulants to prevent stroke?

How Well It Works

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Anticoagulants have been shown to reduce the risk of stroke in people who have atrial fibrillation.¹

Side Effects

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Anticoagulants may cause:

• Easy bruising.
• Bleeding anywhere in the body.
• Skin rash.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

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If you are taking anticoagulants, notify your doctor immediately if you have:

• Unusual bruising or red or purple spots on the skin.
• Unusual bleeding from the nose or gums or if you are spitting up blood.
• Blood in your urine.
• Red stools or stools that look like black tar.
• Blood or material that looks like coffee grounds in vomit.
• Abnormally long menstrual periods.

Safety tips when taking anticoagulants may be helpful, such as taking your medications at the same time each day and watching for signs of bleeding.

What to do if you miss a dose of anticoagulant:

• If you remember it in the same day, take the missed dose. Then go back to your regular schedule.
• If it is the next day, or almost time to take the next dose, do not take the missed dose. Do not double the dose to make up for the missed one. At your next regularly scheduled time, take your normal anticoagulant dose.
• If you miss your dose for 2 or more days, call your doctor.

Do not double the dose in any one day to make up for a missed dose. Call your doctor if you are not sure what to do if you missed a dose.

Atrial fibrillation caused by rheumatic heart disease usually requires a higher dosage of anticoagulant.

You will need to have your blood tested periodically to check your prothrombin time (clotting time) while taking anticoagulant medications. Your clotting time is usually reported in INR (which stands for international normalized ratio). Most people should have an INR between 2 and 3 to have the best protection against stroke. Anticoagulant therapy requires regular monitoring because high levels of anticoagulants increase the risk of bleeding, while levels that are too low increase the risk of stroke and heart attack.

Women have a higher incidence of bleeding while taking anticoagulants than men and may require more frequent monitoring.²

Women with atrial fibrillation who are pregnant or plan to become pregnant should talk with their doctor about the potential benefits and risks of taking anticoagulants. In particular, women should not begin taking warfarin (such as Coumadin) during pregnancy and should not become pregnant while taking it, because it can cause birth defects. Check with your doctor immediately if you are taking this medication and think you may be pregnant. Use of some anticoagulants, such as heparin, may complicate pregnancy and childbirth and can increase the risk of developing osteoporosis or thrombocytopenia if taken over the long term. Other anticoagulant medications are available for pregnant women.

Anticoagulants interact with other medications and some foods. Don't suddenly change your intake of vitamin K–rich foods, such as broccoli, cabbage, asparagus, lettuce, and spinach.

Alcohol can change the way an anticoagulant works. Do not drink alcohol while taking anticoagulant medications. Also, talk to your doctor or pharmacist about possible interactions that anticoagulants may have with your current medications.

To avoid bleeding, take special care when you shave and when you brush and floss your teeth:

• Use only a soft toothbrush, and floss very gently.
• Use an electric razor instead of a blade to shave.

Do not participate in contact sports or other potentially hazardous activities while taking anticoagulant medications. Immediately report to your doctor any falls, blows to the body or head, or other injuries.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.

References

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Citations

1. Albers GW, et al. (2001). Antithrombotic therapy in atrial fibrillation. Chest, 119(Suppl 1): 194S–206S.

2. Humphries KH, et al. (2001). New-onset atrial fibrillation: Sex differences in presentation, treatment, and outcome. Circulation, 103(19): 2365–2370.

Credits

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Author	Robin Parks, MS
Editor	Kathleen M. Ariss, MS
Associate Editor	Pat Truman
Primary Medical Reviewer	Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer	Laurence Epstein, MD - Cardiac Electrophysiologist
Last Updated	January 18, 2007