Nearly 40 percent of atrial fibrillation (AF) patients with an intermediate to high risk of stroke are not receiving optimal treatment, according to a June 20 study in the Journal of the American College of Cardiology.

These patients are being treated with aspirin alone, when previous research has shown such an approach to be inferior to blood thinners.

"Stroke prevention is critical to the management of AF patients. However, giving aspirin alone to this population may not be the best treatment therapy because it is either minimally effective or not effective at all and still comes with risks, such as intracranial hemorrhage," said lead author Jonathan C. Hsu, MD, cardiologist at UC San Diego Health and assistant clinical professor of medicine at UC San Diego School of Medicine.

Researchers from the University of California San Diego School of Medicine and University of California San Francisco School of Medicine examined 200,000 AF patients with medium to high risk of stroke.

Additionally, one in three patients without significant coronary artery disease were prescribed both aspirin and blood thinners, which increases bleeding risk without any evidence of benefits.

"The combination of drugs does not necessarily reduce cardiovascular events and stroke in an AF patient population and likely increases the risk of bleeding," he said.

The authors attribute concerns for bleeding may lead physicians to avoid prescribing blood thinners to AF patients. The misconception that aspirin is sufficient for such individuals may also be a factory. The researchers said more studies must be done evaluating cardiovascular outcomes for AF patients should be conducted.