A newer type of blood-thinning medications, non-vitamin K oral anticoagulants (NOACs), is now recommended as the preferred alternative to warfarin for reducing the risk of stroke associated with atrial fibrillation (AFib), according to a focused update to the 2014 American Heart Association/American College of Cardiology/Heart Rhythm Society Guideline for the Management of Patients With Atrial Fibrillation.

3D Model of the heart by Dr. Matthew Bramlet. Credit: NIH

AFib is a type of irregular heartbeat in the atria, or upper chambers of the heart. Because the heart beat is irregular, blood can pool and then clot inside the atria, particularly in the left atrial appendage, a pouch that is part of the anatomy of the upper left chamber of the heart. If the clots formed within the left atrium migrate within the blood and reach the brain, a stroke caused by a blocked artery can occur even in people with no obvious symptoms of AFib.

Blood-thinning medications called anticoagulants have long been recommended to reduce the risk of stroke in patients with AFib who have an increased risk of thromboembolism (blockage of a blood vessel by a clot travelling in the bloodstream) and/or stroke caused by narrowed or blocked arteries

To reduce stroke risk in appropriate AFib patients, a newer class of anticoagulants known as NOACs is now the preferred recommended drug class over the traditional medication warfarin, unless patients have moderate to severe mitral stenosis (narrowing of the mitral valve) or have an artificial heart valve. NOACs include dabigatran, rivaroxaban, apixaban and edoxaban.

“Patients with AFib are at increased risk of stroke, which can be devastating. A goal of treating AFib patients is to make blood less likely to form clots, which reduces the risk of stroke. New scientific studies show that NOACs may be safer for patients because there is less risk of bleeding, and they may also be more effective at preventing blood clots than warfarin,” said Craig T. January, M.D., Ph.D., co-chair of the focused update published simultaneously in the American Heart Association journal Circulation, Journal of the American College of Cardiology and the Heart Rhythm Society journal, HeartRhythm.

Guidelines rank recommendations as strong, weak, or harmful on the basis of the quality and quantity of the scientific research that supports each recommendation. Recommendations with the highest level of evidence have more than one randomized controlled trial reporting similar results, whereas the lowest-ranked recommendations are based on the clinical experience of experts. Along with the strong recommendation to use NOACs in favor of warfarin for many patients, the new guidelines recommend:

Weight loss for overweight or obese patients. Studies find that losing weight can reduce the health risks associated with or even reverse AFib. It can also lower blood pressure (high blood pressure is often associated with AFib).
New drugs are available to reverse the effect of NOACs (called reversal agents). These reversal agents, while used infrequently, are helpful when there are signs of severe bleeding caused by a NOAC or when a patient on a NOAC needs an emergency surgical procedure.
“AFib patients should talk to their healthcare provider about any concerns they have about their prescribed medications and whether or not losing weight would benefit their health,” said January, who is professor of cardiovascular medicine at the University of Wisconsin in Madison, Wisconsin.

The new guidelines also suggest that NOACs could even be used in people at lower risk of stroke than previously thought. Although the evidence for this recommendation is not yet definitive, emerging research is beginning to suggest that the benefit of NOACs for reducing stroke risk outweighs the risk of taking them, said January.