Improved treatment of a common abnormal heart rhythm has not led to fewer related strokes, according to a study being presented Sunday at the American College of Cardiology’s Annual Scientific Session.

“Atrial fibrillation continues to be a major challenge to the U.S. healthcare system, causing significant morbidity, mortality as well as healthcare costs,” said Arun Mahankali Sridhar, M.D., M.P.H, lead study author and cardiology fellow at the University of Kansas Medical Center, Kansas City, Kan.

“This study underscores the importance of early recognition and aggressive management of this disease,” said Dhanunjaya Lakkireddy, M.D., senior researcher and professor and director of the Center for Excellence in Atrial Fibrillation at the University of Kansas Medical Center.

The number of ischemic strokes associated with atrial fibrillation increased from about 71,000 in 2003 to 101,000 in 2010, according to researchers. Ischemic strokes are caused by blood clots in vessels in or near the brain. Atrial fibrillation is an abnormal heart rhythm that causes the heart to quiver and can lead to blood clots, stroke and heart failure.

Of more than 3 million strokes evaluated, 22 percent were related to Afib, according to the study abstract. Deaths from strokes related to Afib were higher than non-Afib strokes—10.4 percent versus 4.4 percent. In addition, they were more severe and caused longer hospital stays and higher costs.

Afib-related strokes were more common in older people, women and whites, according to the study abstract. They made up more than 40 percent of strokes in people age 85 and older, 24.2 percent of women’s strokes versus 18.7 percent of men’s, and 25.2 percent of strokes in whites versus 11.4 percent in blacks.

The results surprised researchers, said Sridhar, who expected a drop in Afib-related strokes due to improved awareness of Afib and its link to stroke in the medical community and general public. New antiarrhythmic drugs, advanced anticlotting drugs known as anticoagulants and advanced medical procedures including ablation are more available now than a decade ago.

“The comorbid conditions that increase the risk of AF like hypertension, diabetes, sleep apnea and age are increasing in the western world, which will increase the risk of AF and related stroke,” Lakkireddy said. “We should all strive towards better risk factor modification and early detection and treatment.”

Symptoms of Afib include a rapid and irregular heartbeat, a fluttering or thumping in the chest, dizziness, weakness, shortness of breath and anxiety, according to the American Heart Association. People with Afib may also have chest pain or pressure, but are encouraged to call 9-1-1 immediately if they experience it, because it may indicate a heart attack.

“We still see many patients in whom stroke is the first presentation of the atrial fibrillation – meaning the patient does not know he had atrial fibrillation until he presents with a stroke,” said Sridhar. “So it is important to spread awareness of this disease and teach patients at risk about the symptoms of atrial fibrillation, so it could be caught early.”

He and Lakkireddy encourage healthcare professionals and patients to use World AF Awareness Day, the second Saturday in September, to spread the word.

For patients who know they have Afib, studies show that new anticoagulant medications are effecting in preventing stroke, Sridhar said.

“Compliance is probably the most vital issue as opposed to the choice of anticoagulant agent. AF patients just need to be thoroughly educated on the stroke risk, and as long as they are doing the right thing by being compliant with their medications, and following their doctor’s recommendations, their stroke risks are minimized,” Sridhar said.

This study highlights the importance of promoting further research into mechanisms of AFib-associated stroke and treatment strategies for this challenging disease, said researchers.