One of the most frightening aspects of atrial fibrillation — the most common kind of arrhythmia or irregular heartbeat — is the risk of a life-threatening stroke.
During atrial fibrillation, the heart’s two small upper chambers or atria beat chaotically, increasing the risk of blood clots. If a clot breaks free and travels to the brain, you can suffer a stroke which can be fatal. People with atrial fibrillation are five times more likely to have a stroke than those who don’t have the condition. In fact, one in four strokes in people over the age of 80 is a direct result of atrial fibrillation. That makes stroke prevention a key part of atrial fibrillation treatment.
Stephen Kopecky, MD, professor of medicine at the Mayo Clinic and president of the American Society for Preventive Cardiology, said that when working with patients who have atrial fibrillation, the biggest hurdle is deciding whether to prescribe an anticoagulant — a medication to prevent blood clots from forming. Because the average age of an atrial fibrillation patient is 76 years old, the risk of stroke has to be weighed against the risk of bleeding. After that, he said, the decisions get easier.
Preventive Treatment: Anticoagulant Pros and Cons
Anticoagulants, commonly called blood thinners, are medications that slow the clotting of blood, so they help prevent blood clots from forming and traveling to the brain to reduce stroke risk.
If your doctor is concerned about your stroke risk, the first line of preventive treatment is medication. Since the 1950s, warfarin (Coumadin) has been the most widely used anticoagulant. In the last few years, newer anticoagulants such as apixaban (Eliquis), dabigatran (Pradaxa), and rivaroxaban (Xarelto) have gained U.S. Food and Drug Administration (FDA) approval.
Aspirin reduces the risk of stroke by 20 percent; anticoagulants reduce that risk by 80 percent.
Because most people with atrial fibrillation are older, various factors need to be considered. Dr. Kopecky said the risks for stroke are higher in those who have diabetes, high blood pressure, or have experienced heart failure, making an anticoagulant an important part of overall treatment.
Kopecky said fragile patients who fall are at increased risk of problems from internal and external bleeding or who can’t remember to take medication as prescribed probably shouldn’t be taking an anticoagulant. For them, he said, it’s probably wise to simply recommend an aspirin every day. Aspirin reduces the risk of stroke by 20 percent. Anticoagulants reduce that risk by 80 percent.
For atrial fibrillation patients who have equal risks of bleeding and stroke, doctor and patient should together make an informed decision based on factors such as lifestyle, diet, physical activity, access to clinics and doctors, work, and travel. “Every patient is an individual,” said Andrew K. Krumerman, MD, a cardiologist at Montefiore Medical Center in New York and associate professor of clinical medicine at Albert Einstein College of Medicine, “and the decision about what medication to take should not be dictated by what you read in the media or what you hear from pharmaceutical companies, but by a long conversation between patient and doctor.”
Atrial Fibrillation Anticoagulants: Warfarin
Warfarin is a powerful drug that reduces the chemical reaction of vitamin K in the liver that causes — and lengthens the time it takes for — blood to clot. Its effectiveness depends on the amount of vitamin K in the body.
Vitamin K is found in many leafy, green vegetables such as spinach, Brussels sprouts, and kale. Warfarin interacts with those vegetables and with various medications, supplements, and over-the-counter drugs, making it vital that people on it be monitored at least once a month. Too much warfarin increases the risk of bleeding, and too little increases the risk of stroke. No new foods or medicines should be added or eliminated without consulting a doctor, and you’ll want to seriously limit the amount of alcohol you drink.
Patrick J. Tchou, MD, a cardiologist, associate section head of electrophysiology and cardiac pacing in the Robert and Suzanne Tomsich Department of Cardiovascular Medicine, and co-director of the Ventricular Arrhythmia Center at the Cleveland Clinic, said he still considers warfarin to be the gold standard for comparison with other anticoagulants. But the drawbacks, he noted, are that doses have to be individually adjusted, and a patient has to carefully watch levels of vitamin K. If you’re able and willing to regularly go for blood level measurement checks and keep in touch with your doctor about any diet or lifestyle changes, warfarin may be a good choice.
Warfarin is inexpensive when covered by insurance. Unlike some of the newer anticoagulants, an antidote exists for emergency situations such as during surgery when the drug must be immediately counteracted.
In addition to risks of internal bleeding, side effects can include headaches, confusion, weakness, fever, numbness, nausea, and diarrhea — contact your doctor immediately because you may need a dose change.
Atrial Fibrillation Anticoagulants: New Options
Newer anticoagulants have now been proven to be as effective as warfarin, said Kopecky. According to a report in the September 2011 issue of the New England Journal of Medicine, several important studies showed they’re equal or superior at preventing blood clots than warfarin.
The drugs Pradaxa (dabigatran) and Eliquis (apixaban) are taken in fixed doses twice a day, get into the blood in a matter of hours, and don’t require close monitoring or dietary considerations. Xarelto (rivaroxaban) is taken in a fixed dose once a day for prevention of stroke in atrial fibrillation. However, these are not advised for anyone with heart valve disease or serious kidney or liver problems and, unlike warfarin, they’re expensive, costing about $3,000 a year. Side effects are similar to those of warfarin.
“As we get to know these drugs better,” said Kopecky, “we’re migrating toward them more.” He said he likes to recommend them for patients younger than 65, who are active and have no other health issues. “The only considerations when deciding which medication to put a patient on now,” he said, “are individual safety issues and cost.”