Under-treatment of atrial fibrillation persists

A newly published study led by researchers at the Bloomberg School of Public Health examines the trends of treatment for atrial fibrillation (AF) in the form of oral anticoagulants or blood thinners.

Until recently, warfarin was the recommended drug for AF patients who are susceptible to strokes. However, due to several significant drawbacks including potential hemorrhages, new drugs have been developed to circumvent these problems.

Surprisingly, however, despite having a newly-approved, safer pharmaceutical drug for these patients, called dabigatran, under-treatment of atrial fibrillation still occurs.

According to the National Institutes of Health, atrial fibrillation is the most prevalant form of cardiac arrhythmia. While arrhythmia is primarily associated with rapid heart rate, exercise intolerance, shortness of breath and other threatening symptoms, stroke is a large concern for patients with AF.

In AF, the heart demonstrates a lack of atrial contraction, which leaves a large volume of blood in the left atrium. The stagnant blood that remains in the compartment can form clots, leading to the formation of an embolus — a clot that is carried throughout the blood circulation.

At any point, these patients can have a stroke when the clot plugs one of their blood vessels. Thus, developing a drug that would lower the chances of a stroke has been a crucial research focus area in the pharmaceutical field.

Warfarin is a vitamin-K antagonist, which is generally cumbersome to use due to its interactions with food and other drugs. It has been shown that many patients on warfarin still have inadequate anticoagulation.

Dabigatran, on the other hand, is a different type of anticoagulant. It is a direct thrombin inhibitor, lowering the rate at which the thrombin enzyme produces the strands of fibrin, which make up blood clots. Dabigatran has demonstrated effective anticoagulation and a reduced need for constant blood tests to monitor drug side effects.

In the study, published in the September issue of Circulation: Cardiovascular Quality and Outcomes, the researchers found that by 2011, dabigatran had become the anticoagulant of choice in 19 percent of office visits, compared with 81 percent for warfarin when an oral anticoagulant was prescribed.

However, while dabigatran has been swiftly adopted into clinical practice since its FDA approval in 2010, a large portion of patients with AF — 2 out of 5 — did not receive oral anticoagulant therapy. This came as a major surprise to public health experts who expected to see a decrease in the under-treatment of AF.

Instead, dabigatran was commonly used for off-label purposes. In fact, only 63 percent of dabigatran prescriptions that occured during office visits were for AF treatment purposes.

Thoroughly elucidating how anticoagulant therapies like dabigatran are being used in medicine is a crucial step in understanding how to improve care for AF patients.