Atrial fibrillation, or AFib, is a type of irregular heart rhythm that causes your heart to pump less effectively than it should. You’ll get treatment to try to bring back a normal rhythm. Another important part of AFib treatment is anticoagulation. This helps prevent a stroke by lowering your blood’s ability to clot.
Experts say your chances of having a stroke more than double when you have AFib. With the condition, your heartbeats don’t always pump all of the blood out of the upper chambers of your heart, called the atria. Blood can pool there, allowing it to clot. If a clot then gets pumped out into your bloodstream, it can block blood flow inside your brain and cause a stroke or injuries to other organs.
Medicines called anticoagulants can protect you from blood clots, but they aren’t recommended for everyone with AFib. Your doctor will consider whether your stroke risk is higher because of other things including your age, sex, other health conditions, and whether you’ve had a stroke before. They’ll also consider how likely you are to have serious side effects from this kind of medication, like uncontrolled bleeding.
What Are Anticoagulation Treatments for Ongoing Stroke Prevention in Adults With Atrial Fibrillation (Afib)?
Medications used for anticoagulation are also known as blood thinners. While they don’t actually thin your blood, they do make it clot more slowly.
Blood clots are made up mainly of blood cells called platelets, red blood cells, and a sticky, stringy protein called fibrin that helps hold everything together.
Substances called clotting factors control the process. Most are made in your liver, and they’re identified by Roman numerals. Clotting factors circulate in your bloodstream and activate when something triggers them—like a cut that needs to be healed. Then they work together to signal your body to make fibrin.
Anticoagulants lower the activity of clotting factors. When you take them for AFib stroke prevention, they make it harder for a dangerous blood clot to form. But they also make it harder for bleeding to stop.
Which Anticoagulants Are Used to Treat AFib?
Several different classes of drugs can be used to prevent blood clots when you have AFib. They block the clotting process in slightly different ways. They are:
Direct oral anticoagulants (DOACs) – thrombin (factor IIA) inhibitors
Direct oral anticoagulants (DOACs) – factor Xa inhibitors
Vitamin K inhibitors
Low-molecular-weight heparin
What Are Direct Oral Anticoagulants (DOACs)?
DOACs seek out and attach to certain clotting factors, which stops them from taking part in the clot-forming process. With dabigatran, it’s factor IIa, or thrombin. With apixaban, edoxaban, and rivaroxaban, it’s factor Xa.
This is the newest drug class approved for stroke prevention in AFib and the type of drug prescribed most often.
What Is Warfarin?
Warfarin is a vitamin K antagonist. Your liver needs vitamin K to make certain clotting factors. Warfarin lowers the amount of vitamin K in your body that’s available for this purpose.
A downside of taking warfarin is that the dose you need to keep a balance between too much and too little clotting can change often. You have to test your blood clotting time often — every few days at first and monthly later — and adjust your dose as needed. Many things can affect how well the drug works. You need to eat consistent amounts of foods high in vitamin K, like leafy greens, and be careful with alcohol and NSAID pain relievers.
Warfarin was the go-to anticoagulant for decades and is still recommended over other drugs if you have an artificial heart valve or severe valve damage caused by rheumatic fever called mitral stenosis.
What Are Heparins?
Heparin was the first type of anticoagulant medication. It boosts the action of a protein that naturally blocks clotting factors. It isn’t used for day-to-day management of AFib stroke risk except in very specific situations.
If you’re prescribed a heparin drug, it will most likely be before, during, or after an AFib treatment procedure called cardioversion or for a short time after you start taking warfarin and are waiting for it to take full effect. Because it doesn’t cross the placenta, heparin may be recommended if you’re pregnant and are at high risk of a stroke.
There are two forms of heparin. Unfractionated heparin is delivered through a needle placed into a vein in your arm. Low-molecular-weight heparin is made by breaking down heparin into smaller particles. It comes as a shot you give yourself under your skin.
When Are Anticoagulants Prescribed for AFib?
Your doctor may prescribe an anticoagulant for AFib if:
- Your risk of stroke is higher because you’re 65 or older, you’re female, you’ve had a stroke or heart attack before, or you have a condition such as high blood pressure, diabetes, congestive heart failure, or blood vessel disease.
- You have a mechanical heart valve or mitral stenosis.
- You’re having a cardioversion procedure to reset your heart rhythm, which can dislodge a clot from your atria.
How Do You Take Anticoagulants?
Most anticoagulants prescribed for AFib are pills you take either once or twice a day. With DOACs, the dose depends on how healthy your kidneys are. With warfarin, your doctor will prescribe a starting dose based on things like your age, weight, and other medicines you take. But you’ll adjust that to keep your clotting time in a safe range. Heparin is typically given as an injection or through an IV in the hospital.
You may take anticoagulants long term — even for life — as long as your risk of having a stroke outweighs your risk of uncontrolled bleeding. Be careful to take your medication on schedule and don’t miss a dose.
How Effective Are Anticoagulants in Preventing Stroke?
All of the FDA-approved anticoagulants work well to lower your risk of stroke when you have AFib. DOACs are prescribed most often based on clinical trials that showed them to be at least as effective as warfarin, but safer overall.
Are Anticoagulants Safe?
Most people take anticoagulants safely. But they can cause life-threatening side effects.
All anticoagulants make serious bleeding more likely by lowering your blood’s ability to clot. Warfarin products come with a boxed warning about the risk of fatal bleeding, which is the strongest warning the FDA requires on medication labels.
There are drugs that can reverse the effects of anticoagulants in an emergency. You should get help right away if you get a sudden intense headache, you vomit blood, or if you have bleeding you can’t stop. Call your doctor if you have an accident or hit your head, and also let them know if you:
- Bruise easily
- Often feel dizzy
- Have bloody or black stools
- Notice discolored urine
- Have unusually heavy periods
Because of the bleeding risk, you may need to stop taking an anticoagulant before you have surgery or certain other medical or dental procedures. It’s important to follow your doctor's instructions exactly about when to stop and when to start back up.
DOACs have a boxed warning against stopping the drug suddenly. If you do, you raise your chances of having a blood clot. You’re also at risk for bleeding around your brain and spinal cord if you have a procedure like a spinal tap or epidural anesthesia.
It’s rare, but taking warfarin can also lead to clots in tiny blood vessels that can cause skin damage.
What Are the Common Side Effects of Anticoagulants?
Bleeding is the most common side effect of anticoagulants. While it can be serious, it’s usually minor — things like bleeding gums when you brush your teeth or a shaving nick that takes several minutes to stop bleeding. Other side effects include gastrointestinal issues like indigestion and stomach pain.
Who Should Not Take Anticoagulants?
Anticoagulants aren’t right for everyone with AFib. People who have a bleeding or blood clotting problem shouldn’t take them.
You also shouldn’t take DOACs when you’re pregnant because not enough research has been done to show whether they’re safe. If you’re at high risk of a stroke — for example, because you have mitral stenosis — you may get warfarin or heparin.
How Much Do Anticoagulants Cost?
The amount you’ll pay for anticoagulants depends on which medication you’re prescribed and what type of insurance you have. Without insurance or discounts, brand-name DOACs can cost more than $500 a month. Warfarin is much less expensive. Some pharmacies offer it for less than $10 a month.
Some drugmakers offer programs to help cover your out-of-pocket costs or even provide your medication free if you qualify. Learn more by following these links:
- Eliquis 360 Support
- Bristol Myers Squibb Patient Assistance Foundation
- Xarelto withMe
- Johnson & Johnson Patient Assistance Program
Clinical Trials of Anticoagulants
Doctors are always working to improve AFib treatment. Clinical trials are an important part of that process. These are scientific studies that test the safety and effectiveness of medications and other treatments in people.
With anticoagulants, the goal of research is to find the most effective ways to prevent blood clots and stroke while raising your risk of uncontrolled bleeding as little as possible. A possible new target for anticoagulation is clotting factor XI. A biologic drug that blocks its action, abelacimab, is in clinical trials.
Other studies are looking at:
- Whether you can safely stop taking anticoagulants after a successful cardiac ablation procedure
- Whether you can safely stop taking anticoagulants after an AFib treatment procedure called a left atrial appendage closure
- Whether DOACs are safe if you’ve had brain bleeding
- How to more accurately predict your risk for a stroke
If you’re interested in taking part in a clinical trial, the first step is to talk to your doctor. They know your condition best and can tell you what type of study would be helpful and safe for you to join. They may also be able to connect you with a clinical trial happening in your area.
Are Anticoagulants Right for Me?
Your doctor will tell you whether they recommend an anticoagulant as part of your AFib treatment to lower your chances of having a stroke. But it’s important to discuss with them the risks and benefits of this type of treatment and of the different medication options. Here are five things to keep in mind.