Newer Blood Thinner Gaining Affirmation

Apixaban may better prevent strokes than warfarin in atrial fibrillation patients

(RxWiki News) Patients with atrial fibrillation, a common heart arrhythmia, have a higher risk of experiencing a stroke or blood clots. Warfarin (Coumadin) has long been the gold standard in treatment. That could be changing.

A new study suggests that newer anticoagulant apixaban (Eliquis) may be more effective in preventing strokes, and also safer because of a lower risk of major bleeding.

"Discuss anticoagulant options with your cardiologist."

The findings suggest current bleeding risk scoring commonly used to choose anticoagulant therapy may not be as relevant when it comes to prescribing apixaban to patients with atrial fibrillation and at least one risk factor for stroke.

The scoring system assigns points for factors such as heart failure, hypertension and older age. Patients with higher scores are considered to have a greater bleeding risk.

Renato Lopes, MD, a Duke University Medical Center cardiologist and the lead author of the study, said the benefits of apixaban are preserved regardless of the risk score or risk category of the patient. He also noted that apixaban tended to cause less intracranial bleeding in patients with the highest bleeding risk.

Dr. Lopes suggested that risk scores may not be necessary in anticoagulant treatment decisions for preventing strokes in individuals with atrial fibrillation.

Warfarin has long been the standard of care, but it requires regular blood tests and may interact with certain foods and other medications.

Warfarin is a vitamin K antagonist that has been shown to prevent blood clots and reduce the risk of strokes, while apixaban is an oral direct factor Xa (part of the body's system to create blood clots) inhibitor.

A previous large scale randomized, double-blind clinical trial called ARISTOTLE also found that apixaban was safer than warfarin, and that the newer drug carries a substantially lower risk of major bleeding or discontinuation.

Researchers also found that apixaban users were 21 percent less likely to have a stroke or systemic embolism compared to those taking warfarin.

During the current study, investigators analyzed data from the ARISTOTLE trial, which involved 18,201 patients followed an average of 1.8 years. The review was concentrated on popular risk assessment scores used to estimate the risk of stroke and bleeding in patients with atrial fibrillation.

Dr. Lopes noted that treating high risk patients can be tricky because most with the greatest risk of stroke also have a high risk of major bleeding. The traditional risk scoring doesn't necessarily consider such factors when determining the best course of treatment.

"Our study shows that irrespective of the risk of stroke or bleeding, apixaban is more effective and safer than warfarin across all patients with atrial fibrillation and at least one additional risk factor for stroke," Dr. Lopes said.

"Thus, the current risk scores used in clinical practice for patients with atrial fibrillation may play less of a role in decision-making because we now have more efficacious and safer drugs."

While apixaban may prove to have a slight edge in preventing stroke, cost-effectiveness studies are still needed to determine whether the added cost is worth the extra benefit. Warfarin is widely available in a generic form, though extra doctor appointments for monitoring are required. Apixaban is available as a brand name only.

A study recently published in Neurology suggested that warfarin therapy costs about $378,500 and adds 3.9 years of quality life expectancy compared to $381,700 for 4.2 additional quality years with apixaban. However, for most patients apixaban would likely result in higher drug copays.

The research was funded by Pfizer and Bristol-Myers Squibb, which developed apixaban in a joint venture. The study was recently published in The Lancet.

Review Date: 
October 3, 2012