Atrial Fibrillation and Stroke Prevention

What’s the connection between atrial fibrillation and stroke prevention?

Atrial fibrillation increases the risk for stroke. So stroke prevention is an important part of treatment for atrial fibrillation.

Atrial fibrillation is a type of abnormal heart rhythm. The heart has 4 chambers: 2 upper atria and 2 lower ventricles. Atrial fibrillation causes the atria to quiver or “fibrillate” instead of contracting normally. The disorganized signal spreads to the ventricles, and it causes the ventricles to contract irregularly. The contraction of the atria and the ventricles is no longer coordinated. So the amount of blood pumped out to the body will vary with each heartbeat. The ventricles may not be able to pump enough blood to the body.

The blood in the atria can start to pool instead of moving forward normally into the ventricles. This increases the risk of forming blood clots. These clots can then travel through blood vessels to the brain and cause a stroke. This is why atrial fibrillation greatly increases the risk for stroke. Many people with atrial fibrillation need medicine that makes it less likely for clots to form. As a result, this reduces their risk for stroke.

What are the side effects of medicines for stroke prevention for atrial fibrillation?

Taking medicine to thin the blood helps prevent stroke, but it also increases your risk of bleeding. You may have signs of excess bleeding if your blood isn’t clotting enough. You may have these symptoms:

• Unusual bruising
• Bleeding from the gums
• Blood in the urine or stool
• Vomiting blood
• Nosebleeds

An unusually severe headache might also be a sign of bleeding in the brain.

Follow up closely with your doctor. Take your medicine exactly as prescribed to keep your bleeding risk as low as possible.

How does your doctor decide whether you need medicines for stroke prevention for atrial fibrillation?

Doctors use a risk based scoring system to decide whether you need anticoagulant medicines to help prevent stroke. The scoring system takes into account other risk factors for stroke and assigns each a point value. These risk factors include:

• History of heart failure( 1 point)
• History of high blood pressure (1 point)
• Age 65 to 74 years old (1 point)
• Age 75 or older (2 points)
• Diabetes (1 point)
• Previous stroke or transient ischemic attack (2 points)
• History of vascular disease (1 point)
• Female gender (1 point)

For every one of these factors, the risk of having a stroke increases. If your score is 2 or greater, you are considered to be at higher risk for stroke and blood thinners are recommended. If you have none or only one of these factors, your doctor may want you to take an aspirin every day, or do nothing.

How are strokes prevented in people with atrial fibrillation?

Your doctor will work closely with you to find the right medicines for you to help prevent stroke. Your doctor will consider both your health history and your preferences.

Your doctor may prescribe blood thinners to help prevent clots. Some of these medicines include:

• Antiplatelet medicines, like aspirin or clopidogrel
• Anticoagulation medicines, like warfarin, dabigatran, rivaroxaban, apixaban, or edoxaban

These types of medicines help to prevent blood clots in different ways:

• Antiplatelet medicines affect platelets, fragments of red blood cells involved in clotting
• Anticoagulation medicines work on other parts of the blood-clotting pathway

If you have risk factors for stroke, you will likely need anticoagulation medicines. These medicines require careful monitoring. Your healthcare provider will discuss this with you in detail. You want the blood to clot a little less than it would normally, to help prevent stroke. But you don’t want to stop clotting too much, which can cause extra bleeding.

With warfarin, your healthcare providers use blood tests to make sure the blood is clotting the right amount. They can measure clotting with a PT test (prothrombin time test). This test is usually read as a person’s international normalized ratio (INR). If your INR is too high, your healthcare provider may lower the amount of the medication. If your INR is too low, your healthcare provider may increase the amount of the medicine.

It is very important to take this medicine exactly as your doctor tells you. Other newer anticoagulant medicines do not call for monitoring the INR. But other less frequent blood tests are advised including kidney function tests.

A device called a left atrial appendage occluder is now available in some circumstances, to prevent stroke without having to use lifelong blood thinner. This device occludes the left atrial appendage where most blood clots form. This device is not appropriate for everyone. It is generally considered in those who are at high risk for stroke as well as high risk for bleeding.

What are the complications of medicines for stroke prevention for atrial fibrillation?

There are risks of using medicines that help prevent blood clotting and stroke. These medicines also increase the risk of bleeding. This bleeding can occur anywhere in the body. It can be very dangerous if it happens in the digestive tract. Bleeding inside the brain is also very dangerous. This can actually cause a stroke, something the medicine was supposed to help prevent. People who take anticoagulation medicines like warfarin, dabigatran, rivaroxaban, edoxaban, or apixaban are at greater risk of bleeding than people taking medicines like aspirin.

Another risk is that a person might not be taking enough warfarin. This can lead to another blood clot and stroke.

Your healthcare team will work hard to make sure you are getting the right amount of medicine for you by balancing these risks. He or she will only prescribe medicines if the benefits of stroke prevention are greater than the risks of extra bleeding.

You can reduce the risk for problems from anticoagulation medicines by following your doctor’s orders carefully. Have all your follow-up blood work done as prescribed. This helps make sure that the effects of the medicines won’t be too strong or too weak.

How to manage stroke prevention for atrial fibrillation

Your doctor may give you additional instructions about managing your atrial fibrillation. Make sure all your doctors, dentists, and pharmacists know if you are taking medicines to prevent clots. Ask your doctor before taking any new medicines, even if they are over the counter. These may interact with your anticoagulation medicines. Talk with your doctor about your diet. Certain foods like leafy green vegetables can change your INR. You don’t have to avoid these, but you need to keep the amount of them that you eat about the same from day to day.

Your doctor might make other recommendations about how to lower your risk for stroke. These might include:

• Reducing cholesterol through lifestyle or medicines
• Avoiding smoking
• Being physically active and avoiding obesity
• Avoiding excess alcohol use
• Eating a heart healthy diet

When should I call my healthcare provider?

See a doctor right away if you have any of the following signs:

• Unusual or severe headache
• Confusion, weakness, or numbness
• Bleeding that will not stop
• Coughing or vomiting blood
• Bright red blood in the stool
• Fall or injury to the head

Plan to see your doctor soon if your symptoms are slowly getting worse. Also see your doctor if you have any new mild symptoms or side effects.