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
The FDA has approved four blood thinners in recent years — dabigatran (brand name: Pradaxa), rivaroxaban (Xarelto), apixiban (Eliquis), and edoxaban (Savaysa). Along with warfarin (Coumadin), 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.
This article appeared on FDA's Consumer Updates page, which features the latest on all FDA-regulated products.