Atrial Fibrillation: Stroke Prevention Guidelines & Treatment Options
Atrial Fibrillation and Stroke Prevention: The Basics
Non-valvular atrial fibrillation, or NVAF, is a heart rhythm disorder that causes a rapid and irregular heartbeat (arrhythmia) not due to an abnormal heart valve. NVAF is a type of atrial fibrillation (AF).
During AFib, electrical activity in the heart is disorganized and the heart's blood flow is disrupted. When the blood cannot flow properly, it may pool in the heart chambers and cause a blood clot. These clots can dislodge from the heart and travel towards the brain, blocking a blood vessel and causing a stroke. Because of this, a patient with chronic AF usually takes a blood thinning medication to help prevent a stroke.
However, an alarming study from 2017 noted that 37% of 700 patients with AFib stopped taking their warfarin, a blood thinner, within one year after starting. In addition, 54% of those that had a procedure to normalize their heart rate such as ablation or cardioversion also stopped their blood thinner. Researchers state side effects or inconvenient testing may have played a role. What other options exist?
AFib Sounds Serious: Is It Common?
The CDC estimates that roughly 2.7 to 6.1 million people have atrial fibrillation (AFib), and that number is growing. AFib affects whites more often than blacks, and men more often than women. Roughly 2% of people younger than age 65 have AFib, while about 9% of people aged 65 years or older have AFib.
According to the American Academy of Neurology, roughly 1 in 20 people with untreated AFib will likely have an ischemic stroke in the next year. Treatment for stroke prevention in AFib includes medications to control the heart rhythm and rate, anticoagulants (blood thinners) to help prevent stroke, possible surgery and lifestyle changes.
What Factors Put Me at A Higher Risk for Getting AFib?
During atrial fibrillation (AFib), the two upper (atrial) chambers of the heart beat irregularly and out of sync with the two lower (ventricle) chambers of the heart. Controlling the rate or rhythm of the heart, plus lowering the risk for stroke due to blood clots, are the main goals.
There are many risk factors that may increase your chances of having non-valvular AFib including: advanced age, heart disease, heart damage or a heart attack, high blood pressure, stress, high thyroid hormone levels (hyperthyroidism), excessive alcohol intake, stimulating drugs like caffeine, congestive heart failure, obstructive sleep apnea, or acute infections.
More About AFib Symptoms
There are two types of heart rhythm irregularities in AFib: paroxysmal AFib, which comes and goes and can stop on its own, and chronic AFib, which continues and does not stop.
Some people with atrial fibrillation have no symptoms and only get a diagnosis after a physical exam and testing by their doctor, or after a stroke or mini-stroke. For patients that have Afib symptoms, they may complain that their heart flutters, quivers, palpates or beats against the chest wall. They may feel dizzy, weak and nauseated. They may also have shortness of breath or fainting spells. Chest pain or tightness, confusion or fatigue may be present.
Why Does AFib Lead to a Higher Risk for a Stroke?
A major complication of atrial fibrillation (AFib) is the occurrence of a stroke. Due to irregular heartbeats, blood may not pump out of the heart properly and a clot may form in one of the chambers. A piece of this clot (embolus) may break away and travel to vessels leading to the brain, kidneys, eyes, or peripherally in the arms or legs. The clot can block blood and oxygen flow to the brain.
Roughly 9 out of 10 strokes caused by AF are an ischemic stroke. Taking a blood thinner can reduce the risk of having a stroke by 50 to 70 percent.
Use the acronym F.A.S.T. to recognize a stroke in others:
- Face dropping
- Arms drifting down
- Slurred Speech
- Time to call 911.
How is AFib Diagnosed?
Your doctor will ask about your family history of heart disease and review your specific risk factors for AFib. Your heart rhythm, heart rate and pulse will be checked.
The diagnosis of atrial fibrillation is usually confirmed with an electrocardiogram (EKG), a test that records the heart's electrical activity. However, atrial fibrillation may not always be constant, so a standard EKG may be normal and it may be difficult to detect abnormalities in an office visit. In these cases, a portable EKG, called a Holter monitor, may be worn at home, for 24 hours. Monitors are also available that can be used for longer than 24 hours, if needed.
AFib Treatment: The Basics
Untreated atrial fibrillation (AFib) can double the risk of a heart-related death and can quadruple the risk for stroke; however, many patients are unaware that AFib is even a serious condition. In AFib, the goals are to lower the risk for a stroke and monitor or pursue a normal heart rhythm.
Working in conjunction with their physician, patients may receive treatments that will correct the heart rhythm, undergo surgery, and/or take medications such as:
- blood thinners
- calcium channel blockers (verapamil, diltiazem)
The use of pacemakers or radiofrequency ablation are nondrug alternatives.
Warfarin for Stroke Prevention in AFib: Benefits and Risks
The benefit of anticoagulation outweighs any risk of bleeding into the brain for most patients. Warfarin (Coumadin, generics), a vitamin K antagonist, has been the primary blood thinner in use for decades but carries a small increased risk of bleeding into the brain. In addition, warfarin is hindered by many drug interactions and diet restrictions, like green, leafy vegetables, due to vitamin K content. Increasing vitamin K levels in the body can promote clotting and reduce the effectiveness of warfarin. Patients who take warfarin will require regular blood tests (INR) to maintain a therapeutic dose.
The novel oral anticoagulants Eliquis (apixaban), Pradaxa (dabigatran), Savaysa (edoxaban), or Xarelto (rivaroxaban) may be an alternative for patients currently taking warfarin. Your doctor will determine this.
Other Treatments for Stroke Prevention in AFib
Use of any blood thinner should be balanced with the risk of bleeding. The use of the novel agents Pradaxa, Xarelto, Savaysa, or Eliquis is contraindicated in patients with prosthetic heart valves due to a higher risk for bleeding or stroke. Instead, warfarin is the accepted standard of treatment for AFib stroke prevention in patients with prosthetic heart valves.
In patients with non-valvular AF who are at risk for stroke, using an oral anticoagulant therapy, such as warfarin or one of the novel agents, is likely more effective than using aspirin plus clopidogrel (Plavix), but the bleeding risk may be slightly higher.
Stroke Prevention in Non-Valvular AFib
According to the American Academy of Neurology evidence-based guidelines for stroke prevention in non-valvular atrial fibrillation, blood thinners are now recommended for all patients with AFib, especially with a history of stroke or mini-stroke. The elderly, those with mild dementia, or those at moderate risk of falls can now be included in treatment groups.
The novel blood thinners, including Pradaxa, Xarelto, Savaysa, and Eliquis are available - they work as good or better than warfarin, are less likely to cause bleeding in the brain, and don’t require regular blood tests or dietary restrictions like warfarin.
How Do Risk Factors Affect Treatment Choice in AFib?
Guidelines suggest that for patients at higher risk of intracranial (brain) bleeding with warfarin, dabigatran (Pradaxa), rivaroxaban (Xarelto) or apixaban (Eliquis) should be considered for stroke prevention. Edoxaban (Savaysa) was approved after release of the guidelines but may be another option.
In patients with a higher risk for a stomach bleed, Eliquis may be the treatment of first choice (Level C evidence). If a patient is well-controlled on warfarin, a change to a newer oral anticoagulant is not absolutely required.
According to the guidelines, if warfarin is not an option, consider apixaban as the first drug of choice (Level B evidence), then either dabigatran or rivaroxaban (Level C). Aspirin plus clopidogrel is an option when oral anticoagulants are not available, but bleeding risk may be greater.
Novel Oral Anticoagulants: Pradaxa (dabigatran)
Pradaxa is used to prevent stroke or systemic embolism in patients with non-valvular atrial fibrillation, and does not require regular blood testing for therapeutic effectiveness like warfarin. Studies have shown that the rates of stroke or systemic embolism were lower with dabigatran than with warfarin, rates of intracranial (brain) bleeding occurred less frequently, but GI bleeding may be greater.
Pradaxa is also approved for treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), as well as prevention of DVT and PE following hip replacement surgery.
Take Note: Pradaxa Dosing and Storage
Pradaxa must be taken by mouth once or twice a day depending upon use. Doses may need to be lowered in patients with kidney impairment and for certain drug interactions, for example, dronedarone or ketoconazole. Be sure to review the labeled dosing recommendations for concomitant use of P-gp inhibitors and in patients with reduced kidney function.
An important note: Pradaxa should be stored in the original container; do not put the capsules in pill boxes. Once the Pradaxa bottle is opened, the capsules are stable for only 4 months.
Stomach upset (dyspepsia) is a common side effect with Pradaxa. Patients should not stop taking any blood thinner (anticoagulant) medicine without first talking to their doctor. Discontinuing anticoagulation medicine puts a patient at an increased risk of having a stroke.
Novel Oral Anticoagulants: Xarelto (rivaroxaban)
Rivaroxaban (Xarelto) by Janssen is a blood thinner that inhibits clotting factor Xa. Like Pradaxa, Xarelto is approved to prevent stroke or embolism in patients with non-valvular AF. Xarelto has shown lower rates of intracranial and fatal bleeding when compared to warfarin in clinical trials. Xarelto is given once or twice a day depending upon use and does not require blood testing, but dose adjustments are required in patients with kidney impairment.
Xarelto is also approved for prevention or treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), as well as prevention of DVT following hip or knee replacement surgery. The Xarelto NDA for use in acute coronary syndrome was not approved as trials pointed to major bleeding concerns.
Novel Oral Anticoagulants: Eliquis (apixaban)
Bristol-Myers Squibb's apixaban (Eliquis) is another factor Xa inhibitor approved for stroke prevention in non-valvular AFib. Like Pradaxa and Xarelto, Eliquis caused less intracranial bleeding in studies than warfarin and is likely more effective than warfarin in preventing embolism. Eliquis has also been shown to cause less overall bleeding than warfarin and lower mortality.
Eliquis is taken twice a day and lower doses may be needed if the patient has at least 2 of these characteristics: kidney impairment, lower body weight, or age older than 80 years.
Eliquis has important drug interactions, as well, so always have your pharmacist run a drug interaction screen when medications are started or even stopped.
Novel Oral Anticoagulants: Savaysa (edoxaban)
Savaysa (edoxaban) is an oral, once-daily factor Xa inhibitor anticoagulant approved in January 2015 for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (AF). Savaysa is also used to treat deep vein thrombosis (DVT) and pulmonary embolism (PE) following 5 to 10 days of initial therapy with an anticoagulant (blood thinner) given by injection.
In AFib clinical trials, Savaysa was found to be similar to warfarin for reduced stroke risk and demonstrated significantly less major bleeding compared to warfarin. However, bleeding - including life-threatening bleeding - is still the most serious risk with Savaysa. No antidote is available to reverse the anticoagulant effect of Savaysa.
Antidotes for Newer Oral Anticoagulants
A concern with many of the newer oral anticoagulants is that there is limited availability of antidotes for bleeding.
However, Praxbind (idarucizumab), a reversal agent for Pradaxa was approved in October 2015. Praxbind is a humanized monoclonal antibody fragment (Fab) indicated as a specific reversal agent for the anticoagulant effect of dabigatran. The antidote blocks Pradaxa and prevents its action on thrombin to allow blood clotting.
In studies, the antidote acted to return clotting to normal times immediately with no apparent side effects. With warfarin, (a vitamin K antagonist), vitamin K can be given as an antidote to help stop bleeding.
Patients with Prosthetic Heart Valves
The new oral anticoagulants should not be used in patients with prosthetic heart valves. In clinical trials, users of the new oral anticoagulant drugs like Pradaxa were more likely to experience strokes, heart attacks, and blood clots forming on the mechanical heart valves than were users of the anticoagulant warfarin. There was also more bleeding after valve surgery in the Pradaxa users than in the warfarin users.
Patients with atrial fibrillation should NOT stop taking anticoagulants without first talking to their healthcare professional. Abruptly stopping anticoagulants such as warfarin, Pradaxa, Xarelto, Savaysa or Eliquis can increase the risk of stroke, leading to permanent disability or death.
Cost Concerns with Novel Anticoagulants
Warfarin (brand name: Coumadin) has been used for decades as a blood thinner to control stroke risk in patients with AF. Although additional costs are associated with warfarin blood testing, the drug is very inexpensive itself - costing less than $10 per month for the generic tablets. The newer anticoagulants, while they do not require blood tests, are expensive, costing roughly $400 to $450 per month; your insurance may pay for a portion of this cost, and online coupons may help lower the cash price.
Cost-savings may be available through the manufacturer, too. Some people well-controlled on warfarin may not need to switch to a newer agent. Always discuss the best regimens with your doctor; cost is an important factor.
Finished: Atrial Fibrillation - Stroke Prevention Guidelines & Treatment Options
- American Academy of Neurology. Summary of Evidence-Based Guidelines for Clinicians. Prevention of Stroke in Nonvalvular Atrial Fibrillation. Accessed May 8, 2017 https://www.aan.com/Guidelines/Home/GetGuidelineContent/635
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- Granger CB et al. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med. 2011;365:981-92.
- Patel MR et al. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med. 2011;365:883-91.
- Boehringer Ingelheim Inc. Press Release. Setting the Record Straight: The Facts about Pradaxa (dabigatran etexilate mesylate). Accessed May 8, 2017 at http://us.boehringer-ingelheim.com/news_events/press_releases/press_release_archive/2014/02-13-2014-setting-the-record-straight-facts-pradaxa-dabigatran-etexilate-mesylate.html
- Connolly SJ et al; RE-LY Steering Committee and Investigators. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med. 2009;361:1139-51.
- The Centers for Disease Control and Prevention (CDC). Division for Heart Disease and Stroke Prevention. Atrial Fibrillation Fact Sheet. Accessed May 8, 2017 at http://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_atrial_fibrillation.htm.
- CardioSmart. American College of Cardiology. Atrial Fibrillation Guidelines. Accessed May 8, 2017 at https://www.cardiosmart.org/Heart-Conditions/Guidelines/Atrial-Fibrillation-Guidelines-2014