Atrial fibrillation (AFib) is the most common abnormal heart rhythm. The heart has 2 upper chambers called atria and 2 lower chambers called ventricles. AFib causes the atria to quiver (fibrillate) instead of pumping normally. Blood can then pool in the heart instead of moving in and out as usual. This can cause blood clots to form in the heart. A clot can break free, travel to the brain, and cause a stroke. A stroke can quickly damage the brain.

Your health care provider may prescribe a medicine to help prevent blood clots if you have AFib. This type of medicine is called a blood thinner. Blood thinners include:

• Antiplatelet medicines, such as aspirin or clopidogrel
• Anticoagulant medicines, such as warfarin, or medicines called direct-acting oral anticoagulants (DOACs). These include dabigatran, rivaroxaban, apixaban, betrixaban, and edoxaban.

Blood thinners raise your risk of bleeding. If you take certain blood thinners, you may need to take extra steps to stay healthy. Depending on the blood thinner, you may need regular blood tests to check the levels of medicine in your blood. You'll need to be careful not to injure yourself. And you may need to watch your diet for foods that affect blood clotting. Tell your health care provider if you are pregnant or plan to get pregnant. Many blood thinners can cause birth defects or bleeding that may harm your unborn child.

If your blood is too thin, you may have symptoms of excess bleeding. Call your provider right away if you have any of these symptoms:

• Coughing or vomiting blood or other things that look like coffee grounds.
• Nosebleeds frequently that do not stop quickly.
• Unusual bruising or blood blisters.
• Feel sick, weak, faint, or dizzy.
• Blood in the urine or stool.
• Black stools.
• Bleeding more during your periods or between periods.
• Bleeding gums that do not stop quickly.
• Headache.
• Stomachache.

Take the medicine exactly as directed by your provider. Take it at the same time each day. If you miss a dose, call your provider right away to find out how much to take. Never take a double dose. If you take too much, it can cause too much bleeding. It can cause bleeding you can see on the outside of your body. It can also cause bleeding on the inside of your body that you may not be aware of.

If you take DOACs, you don't need regular blood testing. But you may need to have your kidneys checked regularly. Your provider will discuss this with you.

If you take warfarin, you will need to have your blood closely kept track of and tested on a regular schedule. This is to make sure you don't have too much or too little of the medicine in your blood. Too much can cause extra bleeding. Too little may not prevent blood clots from harming you.

You may need to visit a hospital or clinic every week, or as advised, to have your blood tested. A provider may come to your home and test your blood or you may be able to test your blood at home yourself with a small machine. Talk with your provider to find out what's best for you. After the blood test, your provider may tell you to change your dose of medicine.

Warfarin levels can change with your diet. For example, many foods contain vitamin K. Vitamin K helps your blood clot. You don't need to stop eating foods that have vitamin K. But you do need to keep the amount of them you eat as steady as possible from day to day. Foods high in vitamin K are asparagus, avocado, broccoli, cabbage, kale, spinach, and some other leafy green vegetables. Soybean, canola, and olive oils are also high in vitamin K.

Other foods and drinks can affect the way blood thinners work in your body. These include:

• Grapefruit and grapefruit juice.
• Cranberries and cranberry juice.
• Fish oil supplements.
• Calcium supplements.
• Garlic, ginger, licorice, and turmeric.
• Herbs used in herbal teas or supplements.
• Alcohol.

If any of these items are part of your regular diet, talk with your health care providers about any changes that may be recommended.

Because blood thinners make you bleed more, you'll need to protect yourself from breaks in the skin. Follow these guidelines:

• Don't go barefoot. Always wear shoes.
• Don't trim corns or calluses yourself.
• Use an electric razor instead of a manual one.
• Use a soft-bristled toothbrush and waxed dental floss.

You'll also need to not do any activities that may cause injury. If you fall or are injured, you could be bleeding inside your body and not know it. Get emergency medical care right away if you fall, hit your head, or have any other kind of injury.

While on your medicine:

• Tell all of your health care providers that you take a blood thinner for AFib. This includes your dental care providers and your pharmacist.
• Ask your provider before taking any new medicines, vitamins, or other supplements. Any of these can cause problems when you take a blood thinner.
• Wear a medical alert bracelet or carry an ID card in your wallet if you will be taking blood thinners for months or longer.
• Keep all appointments for your blood tests.

Most blood clots that form in the heart occur in a pouch of the left atrium called the appendage. This pouch can often be large and have multiple lobes. Blood often pools and forms clots here. Left atrial appendage closure is a nonsurgical procedure in which a plug is placed at the opening of the left atrial appendage. This closes it off from the rest of the heart. Once the plug has sealed, no blood can enter or leave the pouch. This reduces blood clot formation and stroke risk. It often does not need you to use blood thinners for the long-term except for aspirin. Ask your health care provider if you qualify for this type of procedure.

Your provider might give you other advice about how to lower your risk for stroke. Tips include:

• Lower your cholesterol with lifestyle changes or medicine.
• Don't smoke.
• Get physical activity.
• Lose weight if needed.
• Eat a heart-healthy diet.
• Don't drink too much alcohol.

Call 911 right away if you have symptoms of a stroke.

Remember: If you have any of the symptoms below, or if someone you are with has these symptoms, call 911 as soon as possible.

Never drive yourself or the victim. The ambulance can alert the hospital and start treatment.

B.E. F.A.S.T. is an easy way to remember signs of a stroke. When you see these signs, you will know that you need to call 911 fast.

B.E. F.A.S.T. stands for:

• B is for balance. Sudden loss of balance or coordination or trouble walking.
• E is for eyes. Vision changes in 1 or both eyes.
• F is for face drooping. One side of the face is drooping or numb. When the person smiles, the smile is uneven.
• A is for arm weakness. One arm is weak or numb. When the person lifts both arms at the same time, 1 arm may drift downward.
• S is for speech difficulty. You may notice slurred speech or difficulty speaking. The person can't repeat a simple sentence correctly when asked.
• T is for time to dial 911. If someone shows any of these symptoms, even if they go away, call 911 right away. Make note of the time the symptoms first appeared.

Also call 911 right away if:

• You have sudden confusion.
• You have an unusual or severe headache.
• You have chest pain.
• You have trouble breathing or shortness of breath.
• You have uncontrolled bleeding.

Contact your health care provider or get medical care right away if:

• You feel sick, weak, faint, or dizzy.
• There's a change in the usual regularity of your heartbeat.
• You are fatigued.
• You have a fever of 100.4°F or 38°C or higher, or as advised by your provider.
• You have new or worse symptoms of AFib.