How to prevent a stroke?


If you’re one of the 2.7 million Americans who have atrial fibrillation, you have an increased risk of a stroke. You can greatly reduce the risk of a stroke by 50% to 60% by taking a blood thinner (anticoagulant).

A stroke occurs when blood flow to the brain is blocked by a clot, depriving brain cells of oxygen. In people with atrial fibrillation, blood flow is sluggish in the top chambers of the heart, and blood clots can form there. When a piece of a clot breaks off, it can travel to the brain and cause a stroke. That’s where blood thinners come in. Blood thinners, or anticoagulants, decrease the chances of blood clots forming in the heart, reducing the risk of stroke.

But as many as half of the people with atrial fibrillation who could benefit from a blood thinner don’t take them. There are two main reasons for this: Anticoagulants don’t affect how patients feel, and they can cause bleeding.

“Most drugs are used to improve how patients feel or function, but anticoagulants aren’t used this way. They are preventive drugs, used to prevent strokes in people who generally feel well,” says Ellis F. Unger, M.D., the Director of FDA’s Office of Drug Evaluation I in the Office of New Drugs.

“When treatment is successful, patients dramatically reduce their risk of experiencing a stroke, but the drugs don’t improve the symptoms of atrial fibrillation,” Unger adds. “So patients don’t feel any noticeable benefit while taking them. But they are well aware of the downside of the drugs — their inconvenience, bleeding side effects, and cost. But when patients avoid anticoagulants for these reasons, they put themselves at risk of irreversible brain damage and disability. The benefit of a decreased risk of stroke clearly outweighs the risks and inconveniences of these drugs.”

New Blood Thinners Available

FDA has approved four blood thinners in recent years — dabigatran (Pradaxa), rivaroxaban (Xarelto), apixiban (Eliquis), and edoxaban (Savaysa). Along with warfarin, a drug approved 60 years ago, these drugs are used to prevent stroke in patients with atrial fibrillation.

There are some important differences among these drugs. Warfarin interacts with certain drugs and foods that make it less effective or more likely to cause bleeding, and so its effects must be monitored with periodic blood tests. The new drugs have fewer interactions and don’t require blood monitoring.

Although all anticoagulants reduce the risk of a stroke caused by clots from the heart, they increase the risk of a stroke caused by bleeding into the brain (a hemorrhagic stroke). The newer drugs cause fewer bleeding strokes than warfarin, and the overall rates of strokes (caused by blood clots or bleeding) are lower with some of the newer drugs.

Another difference is how fast the drugs start and stop working. “When starting warfarin, it takes a few days before the drug takes effect,” Unger says. “And when stopping warfarin, it takes a few days for its effects to wear off.”

He adds: “The new drugs start working rapidly, and their effects wear off fairly rapidly. For most patients, this is an advantage.”

He cautions: “Rarely, however, when patients have life-threatening bleeding or need urgent surgery, it can be important to stop the effects of these drugs immediately.”

For the rare patient with life-threatening bleeding, reversal agents can be used to counter the effects of anticoagulants. For example, Vitamin K is the reversal agent for warfarin. FDA recently approved the first reversal agent — Praxbind (idrucizumab) — for Pradaxa. Praxbind can be used in emergency situations when bleeding caused by Pradaxa’s anticoagulant effects can’t be controlled.

Drugs Help Prevent Strokes

Strokes are often devastating to patients and their families.

“A stroke can ruin a life — or end one. Having a stroke can affect your ability to speak, eat, walk, work, care for yourself, and interact with others,” Unger says. Why don’t more people take blood thinners? “Both warfarin and the new drugs can cause bleeding, and we think fear of bleeding is the main reason many patients do not use them,” he says.

But most bleeding is not serious. It can be as minor as what occurs when you brush your teeth or shave. More serious bleeding, such as internal bleeding, can occur, but it’s rarely life-threatening, he says.

“Bleeding is scary, but it is usually treatable and unlikely to cause permanent damage,” he adds. “And it’s much less dangerous overall than a stroke.”

What You Can Do

If you have atrial fibrillation, talk to your health care provider to make sure you’re being treated properly to prevent stroke. Some factors increase the likelihood that you will have a stroke. They include being 65 or older, having a history of previous stroke, diabetes, high blood pressure, and heart failure. The risks are also higher in women, patients with diminished kidney function, and people with a prior heart attack.

Some patients believe that because their atrial fibrillation is “mild” there is no need for them to take a blood thinner. They may have this impression because their atrial fibrillation causes few symptoms, or because it comes and goes. In fact, their risk of stroke has more to do with other factors and might be quite high, Unger says. So even if you have mild atrial fibrillation or atrial fibrillation that comes and goes, you should have a frank talk with your health care provider about treatment options.

What the Future Holds

FDA continues to work with manufacturers that are studying drugs to reverse the effects of some of the new anticoagulants, Unger says. “We hope these drugs will reduce the consequences of bleeding in some patients, and increase acceptance of anticoagulants in the medical community so that fewer patients with atrial fibrillation go untreated,” he adds.

When the new anticoagulants were being studied, the emphasis was on showing that they worked well compared to warfarin, without the need for blood monitoring. Since then, there has been more interest in individualized treatment. For example, this might include using the new drugs with occasional blood monitoring to further reduce the risks of stroke and bleeding.

“Too little use or underuse of anticoagulants in people with atrial fibrillation is a critical, preventable, public health problem. For most patients with atrial fibrillation, taking an anticoagulant as prescribed is the most beneficial thing you can do to reduce your chance of having a life-changing stroke,” he says.

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New Blood Thinning Medication Is Coming to a Doctor Near You

Physicians have prescribed the blood thinner warfarin (Coumadin) since the 1950s to reduce the risk of stroke in people with atrial fibrillation, a form of arrhythmia or irregular heartbeat. For decades warfarin was the only treatment available, but in the past few years the US Food and Drug Administration (FDA) has approved four new blood thinners. Called novel oral anticoagulants or NOACs, they include dabigatran (Pradaxa), rivaroxaban (Xarelto), edoxaban (Savaysa), and apixaban (Eliquis). At the same time, advances in surgical procedures to reduce the risk of blood clots have allowed some people with atrial fibrillation to stop taking blood thinners altogether.


We asked four stroke experts to compare NOACs with warfarin to help people with atrial fibrillation determine the most appropriate treatment.

Understanding Atrial Fibrillation

Atrial fibrillation is the most common form of heart arrhythmia, affecting 1 percent of the general population and 10 percent of people aged 75 and older, according to data from the Framingham Heart Study, a large and long-running population study.

Normally, the atria, the two upper chambers of the heart, contract regularly and squeeze blood into the ventricles, the two lower chambers of the heart, explains Mitchell S.V. Elkind, MD, a professor of neurology and epidemiology at Columbia University in New York City and a Fellow of the American Academy of Neurology (FAAN) and the American Heart Association. In people with atrial fibrillation, the surface of the atria wriggles like a bag of worms and can’t push all the blood into the ventricles.

Clots Can Be Catastrophic

When this happens, the blood left behind pools in the atrium until the next heartbeat, and that pooled blood is susceptible to clotting. If a clot forms and is pumped to the brain, it can block a blood vessel and cause an acute ischemic stroke. Other factors can lead to a stroke-causing blood clot, but in people with atrial fibrillation, these clots tend to be larger and more devastating, the experts say.

Blood thinners make the blood less likely to coagulate and form clots within the heart, and they have a solid track record of reducing stroke in people with atrial fibrillation, says Dr. Elkind. “Studies looking at large populations show reductions in stroke risk that, on a relative scale, can be as much as 50 or 60 percent. the millions of people with atrial fibrillation, that’s a lot of strokes being prevented.”

The Pros and Cons of Warfarin

In use since the 1950s, warfarin has been studied for decades and has been shown in large-scale trials to reduce the risk of stroke by more than half. Given its safety, affordability, and longevity, it is still the blood thinner of choice for millions around the world.

But the drug has its drawbacks. “The dosing has to be adjusted on a regular basis and the blood levels are very sensitive to diet and other medications,” says James C. Grotta, MD, FAAN, director of stroke research at the Clinical Innovation and Research Institute at Memorial Hermann Texas Medical Center in Houston and director of the hospital’s Mobile Stroke Unit Consortium. “A blood level that is adequate one week may not be adequate the next week, even if you don’t change the dose.”

If the level is too low, blood clots can form in the heart. If it’s too high, the risk of bleeding increases. To monitor these fluctuations, people taking warfarin must have their blood drawn and tested regularly, as often as several times a week to once a month. They also have to watch their diets because certain foods, especially leafy greens such as kale and spinach, contain a lot of vitamin K, which acts as an antidote to warfarin. Sudden changes in physical activity can also affect how the body metabolizes warfarin, so if people become more sedentary or more active, their blood must be monitored to make sure it contains adequate levels of the drug.

For some people, this is a minor inconvenience. Once they get used to the drug and the dietary restrictions and are stable on the medication, they may need to get blood drawn once a month and can remain on the same or a relatively similar dose for years without problems. For others it’s not so easy. “I’ve seen people on crazy warfarin regimens: 10 mg Monday, 5 mg Tuesday, Thursday, and Saturday,” says Sarah Song, MD, MPH, an assistant professor of neurology at the Rush University Medical Center in Chicago and a member of the Neurology Now editorial advisory board. “For some patients it can be really difficult, and the diets can be restrictive, too.”

The Pros and Cons of NOACs

The new blood thinners don’t require the same level of monitoring, dietary restrictions, blood draws, or dose adjustments, and they are at least as effective at reducing the risk of stroke in people with atrial fibrillation, says Antonio Culebras, MD, FAAN, a professor of neurology at SUNY Upstate Medical University in Syracuse, NY. Another advantage? They are less likely to cause bleeding in the brain. These conveniences and advantages are why these blood thinners account for the majority of all new prescriptions, according to a study published online last year in the American Journal of Medicine (AJM).

Still, the newer anticoagulants have some disadvantages. They cannot be used in people with kidney disease or with defective or mechanical heart valves, and they can interact negatively with some medications. And they are much more expensive than warfarin. The AJM study estimated that a six-month supply of any of the NOACs costs on average $900 more than the same amount of warfarin.

Another disadvantage is the risk of bleeding. If a person on warfarin starts bleeding, a doctor can administer a reversal agent that will stop its anticoagulating effects. Currently, no reversal agent exists for NOACs; doctors and patients have to wait until their effects wear off. Luckily, the drugs have a relatively short half-life (the amount of time it takes for half of the drug to leave the system and no longer be effective) of between six and 12 hours. And all four NOACs have potential reversal agents that are currently being tested in advanced clinical trials, some of which may be approved by the FDA within the next year or two, Dr. Culebras says.

Concerns About Bleeding

Anticoagulants keep blood from clotting and causing ischemic strokes. But they also keep blood from clotting quickly when someone begins to bleed—and therein lies the rub. As people age, they are more likely to develop atrial fibrillation and be on blood thinners. But they are also more likely to fall and bleed. That’s enough to prevent some doctors from prescribing blood thinners to the very elderly or frail or those with increased risk of falling.

But Dr. Culebras believes doctors should reconsider. He and two of the other experts cite a landmark study published in the Archives of Internal Medicine in 1999 in which researchers used a statistical model to compare the benefits of anticoagulation with the dangers of bleeding in patients at risk of falling. The study concluded that a patient would have to fall 265 times a year in order for the dangers of falling to outweigh the benefits of blood thinners.

Instead of forgoing blood thinners altogether, Dr. Culebras says doctors should try to address the causes of falling. For example, they can recommend walking aids like canes or walkers or prescribe gait therapy, in which a person is taught how to walk more safely.

Dr. Grotta agrees. “With any medication or procedure there are risks, but the risk of not doing anything with atrial fibrillation is extremely high,” he says.

For Dr. Song, who works in an emergency department, warfarin has yet another advantage. If a person on warfarin arrives with stroke-like symptoms, not only can Dr. Song administer a reversal agent, she can also run blood tests to determine the precise level of metabolized warfarin in the blood. This is particularly important because many people arrive in the ER unable to speak and can’t tell the doctor if they took their medication that day. Armed with this vital information and having determined that the patient is having an ischemic stroke, Dr. Song can then administer intravenous tissue plasminogen activator (tPA), a medication that breaks up the clot, which must be given within four hours of a stroke.

For now, there is no way to determine the levels of NOACs in a patient’s blood, or even if the patient has taken his or her medication that day. So if a patient with stroke-like symptoms has a history of taking a NOAC, doctors may not feel comfortable administering tPA because there isn’t enough evidence to show it will be beneficial and safe. In that case, Dr. Song says, doctors may initiate intra-arterial therapy, which involves inserting a catheter into a blood vessel in the groin, sliding it up to the blockage in the brain, and pulling the clot out using a retrieval device.

Weighing the Odds

Our four experts use a scoring system to assess the risk of stroke in their patients. (See “Calculating Stroke Risk” below.) They also use a scoring system to determine the risk of bleeding based on the following factors: high blood pressure, abnormal kidney or liver function, a history of stroke or bleeding, an unstable rate of blood clotting, age (older than 65), and whether patients take drugs that interfere with clotting, such as aspirin, and/or consume more than eight drinks per week.

If the risk of stroke is greater than the risk of bleeding, physicians normally recommend that people with atrial fibrillation consider taking a blood thinner. But “it is ultimately the patient’s decision,” says Dr. Elkind. “The physician’s role is to give the patient the information to make that decision.”

Stop the Clot

New research suggests surgery may be a viable way to prevent blood clots caused by atrial fibrillation.

The discovery that 95 percent of clots caused by atrial fibrillation form in the left atrial appendage, a small pouch in the wall of the left atrium of the heart, has opened up a variety of surgical treatment options. Today, doctors are experimenting with ways to stop those clots from forming, either by removing the pouch, closing it off, or plugging it with a special device.

One procedure—inserting a small mesh-like plug, called the Watchman, into the left atrial appendage—was approved by the FDA last March. The mesh allows blood to flow through but prevents clots from entering the heart. And because it has been available in Europe since 2005, enough data exist to make it a viable alternative for some patients. Numerous studies reviewed in the European Journal of Cardiovascular Medicine in 2014 show the device is at least as effective as warfarin for preventing strokes.


There are caveats, however. Patients must continue on warfarin for between 45 days and a year after the procedure, so it is not suitable for people who cannot tolerate blood thinners (for example, people with a history of brain bleeds or who must take other medications that interact with blood thinners). And even minimally invasive procedures like this carry risks of complications such as infection or pain, although experts note that improvements in the implanting process and the increasing skill of the doctors carrying out the procedure has reduced the risk of complications. Also, there are not yet enough surgeons trained in the procedure to make it available throughout the country.

These interventions are not yet mainstream, but our experts believe they will become important alternatives to blood thinners. Undergoing a single procedure has obvious advantages over taking a blood thinner every day for the rest of your life, and in theory, surgical options carry no risk of spontaneous bleeding. But these procedures are still in the early stages of development, and while the data have been encouraging, there are still no long-term data about effectiveness and safety.

Got Atrial Fibrillation?

Three questions to ask your doctor.

What is my risk of having a stroke within the next year?

If you have atrial fibrillation, your doctor should be able to determine your risk based on the CHA2DS2-VASc scoring system. (See “Calculating Stroke Risk” below.) Zero means you are at low risk, one means you are at moderate risk and may want to start taking a blood thinner or aspirin as a preventive measure, and two and above means your risk is higher and you should consider blood thinners.

Should I take blood thinners? If so, which one?

If you are at a moderate or high risk of stroke, your doctor should talk you through your options. Together, you should discuss the various clinical and convenience factors and choose the blood thinner that best suits your needs. Remember, some of the newer blood thinners can be very expensive—a factor your doctor should take into account.

Am I a good candidate for a surgical procedure?

Your doctor should discuss the risks and benefits of surgery to remove or block off the left atrial appendage. Not all patients are eligible for these procedures, and while the Watchman device has been approved by the FDA (see “Stop the Clot”), similar devices are still in trial phases and not enough long-term data are available to compare them with blood thinners in terms of safety and efficacy.

Different Types of Strokes

Stroke is the second leading cause of death worldwide, according to the World Health Organization, and is one of the most common causes of disability and reduced quality of life in the elderly.

ISCHEMIC STROKE occurs when a blood vessel in or leading to the brain is blocked, most commonly by a blood clot. Eighty-seven percent of strokes are ischemic, according to the US Centers for Disease Control and Prevention.

HEMORRHAGIC STROKE occurs when a blood vessel bursts and bleeds into the brain, flooding the spaces between cells.

CRYPTOGENIC STROKE is a stroke with no known cause. Undetected atrial fibrillation is believed to be the cause of 30 to 40 percent of these types of strokes, according to an updated guideline by the American Academy of Neurology. Experts recommend monitoring for the condition after a stroke or mini-stroke to determine if it was an underlying cause.

Calculating Stroke Risk

The CHA2DS2-VASc score helps doctors calculate a patient’s risk of having a stroke within the next year. Every risk factor adds one or two points to the patient’s score. The likelihood of having a stroke within the next year is calculated by adding up the points.

Medication after TIA and stroke fact sheet

What you need to know

  • After a transient ischaemic attack (TIA) or stroke, your risk of having another one is higher.
  • Almost everyone will need to take medication to reduce this risk.
  • Never stop taking your medication or change your dose without talking to your doctor.

Blood pressure medication

High blood pressure is the biggest risk factor for stroke. Keeping your blood pressure in the normal range is very important. Normal blood pressure is around 120/80, so if your blood pressure is regularly over 140/80, you have high blood pressure.

If your blood pressure is too high, your arteries can thicken over time. They become weaker, less flexible or more prone to clots, and this can cause a stroke.

Medicines that lower your blood pressure are called anti-hypertensives. Almost everyone who has had a TIA or stroke should take anti-hypertensives, even if their blood pressure is normal. Your doctor will work with you to find out the best medication for you.

Cholesterol-lowering medication

High cholesterol can lead to fatty build-up in the artery walls that narrows or blocks the artery to the brain, causing a stroke. Statins are the most common type of medication used to control cholesterol levels.

Statins are effective in reducing the risk of ischaemic stroke (strokes causes by a blocked blood vessel) regardless of cholesterol level. Higher dose statins are the most effective, so statins are usually prescribed at high doses, even for people with normal cholesterol levels.

Blood-thinning medication

Blood clots can travel through the bloodstream and block an artery in the brain, causing a stroke. Blood-thinning medication lowers the risk of blood clots forming. If you have had a TIA or an ischaemic stroke you will almost always need to take blood-thinners.

There are two types of blood thinners:

Antiplatelet medication. Antiplatelet medicines stop tiny blood cells called platelets from sticking together and forming a blood clot. They are also called platelet aggregation inhibitors. They include aspirin, a combination of aspirin and dipyridamole, and clopidogrel.

Anticoagulant medicine. Anticoagulants stop your blood forming clots in a different way. Anticoagulants include direct-acting oral anticoagulants such as dabigatran, apixaban and rivaroxaban. Warfarin is also an anticoagulant. If you take warfarin, you may need regular blood tests to check the amount of warfarin in your blood. There will also be some dietary restrictions.

If you have atrial fibrillation (irregular heart beat) or certain heart conditions such as a prosthetic heart valve, you should take anticoagulant medication. Take your medication regularly and don’t miss a dose. Your stroke risk goes up very quickly if you miss doses.

Blood thinners can make you bleed more easily. Tell your doctor you are taking blood thinners before you have medical treatments or surgery.

Managing your medications

  • Take your medications at the same time every day.
  • Keep your medications in a place you always visit at the time you need to take them.
  • Use a dosette box that shows the day of the week and time of day. You can also ask your pharmacist to pack all your medicines into a blister or webster pack.
  • If you have a smartphone, there are apps that remind you to take your medications and when you are due for a refill or a new script. These apps make it easy to show the doctors a list of your medicines if you go into hospital.


Take enough medication for your entire trip and keep a few days’ supply with you in your hand luggage. Take a list of your medicines and the dose in case you need to see a doctor while travelling.

Side effects and interactions

If your doctor prescribes a medicine, keep taking it until they tell you to stop. It can be dangerous to suddenly stop taking medicines or change the dose. If you are worried or have questions about your medications speak to your doctor or pharmacist.

Sometimes medicines do not work as they are supposed to. Tell your doctor or pharmacist about everything you are taking, including over-the-counter medicines, natural remedies and vitamins. Your doctor may be able to make changes to reduce or eliminate any side effects or interactions. Your doctor can also organise a medication management review if needed.

More help

The health professionals at StrokeLine provide information, advice, support and referral. StrokeLine’s practical and confidential advice will help you manage your health better and live well.
Call 1800 STROKE (1800 787 653)
Email [email protected]

Join Australia’s online stroke community with videos, fact sheets, resources and support for stroke survivors, their family and friends.

Medicines Line provides information on how medicines work, how to take them, side effects and interactions, and storage
of medicines.
1300 633 424

How can you live a longer, healthier life? These eight key factors can help you lower your risk of heart attack and stroke if you’ve never had one. They’re part of an overall healthy lifestyle for adults. And they can help you build a powerful prevention plan with your health care team (doctors, nurses, pharmacists, registered dietitians, and other professionals).

1. Know your risk.

If you’re between 40 and 75 years old and have never had a heart attack or stroke, use our Check. Change. Control. CalculatorTM to estimate your risk of having a cardiovascular event in the next 10 years. Certain factors can increase your risk, such as smoking, kidney disease or a family history of early heart disease. Knowing your risk factors can help you and your health care team decide on the best treatment plan for you. Many risk factors can be improved with lifestyle changes.

2. Eat a healthy diet.

Center your eating plan around vegetables, fruits, whole grains, legumes, nuts, plant-based proteins, lean animal proteins and fish. Make smart choices like limiting refined carbohydrates, processed meats and sweetened drinks. Use the nutrition facts label on packaged foods to cut back on sodium, added sugars and saturated fats, and avoid trans fat.

3. Be physically active.

Move more – it’s one of the best ways to stay healthy, prevent disease and age well. Adults should get at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous activity each week. If you’re already active, you can increase your intensity for even more benefits. If you’re not active now, get started by simply sitting less and moving more.

4. Watch your weight.

Stay at a healthy weight for you. Lose weight if you’re overweight or obese. Start by eating fewer calories and moving more. You can check your body mass index (BMI). If you need help, talk to your health care team about a weight loss plan.

5. Live tobacco-free.

If you don’t smoke, vape or use tobacco products, don’t ever start. There’s no such thing as a safe tobacco product. If quitting smoking or tobacco is a challenge for you, ask your team for help to kick the habit using proven methods. Don’t just swap one tobacco source for another. And try to avoid secondhand smoke, too!

6. Manage conditions.

If you have high blood pressure (hypertension), high cholesterol, high blood sugar, diabetes or other conditions that put you at greater risk, it’s very important to work with your health care team and make lifestyle changes. Many conditions can be prevented or managed by eating better, getting active, losing weight and quitting tobacco.

7. Take your medicine.

If you have a health condition, your doctor may prescribe statins or other medications to help control cholesterol, blood sugar and blood pressure. Take all medications as directed. But don’t take aspirin as a preventive measure unless your doctor tells you to. If you’ve never had a heart attack or stroke, a daily aspirin may not help you at all and could cause problems including risk of bleeding. If you’ve had a heart attack or stroke, your doctor may want you to take a low dose of aspirin to reduce your risk of having another.

8. Be a team player.

Your health care team can help you reduce your risk of heart disease or stroke to live a longer, healthier life. Work together on your prevention plan. Ask questions, and be open about any challenges you may face in trying to make healthy changes. Stress, sleep, mental health, family situations, tobacco use, food access, social support and other issues all can affect your health and well-being.

Live well today for a healthier tomorrow.

The bottom line? Healthy living is the best way to delay or avoid many heart and brain diseases. This means being active and fit, eating healthy, avoiding tobacco and managing conditions that can put you at greater risk. Take charge of your health. Join Healthy for Good for tips, tools and inspiration to make changes and create healthy habits you can sustain throughout your life.

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