"We're seeing more and more patients with atrial fibrillation," Dr. N.A. Mark Estes III of Tufts University School of Medicine said in a statement. "The good news is that we have practical and useful tools to use in assessing patient risk and good evidence on how to treat this condition."

Atrial fibrillation occurs, when the upper chambers of the heart -- the atria -- quiver in an uncoordinated way rather than contract with a steady tempo. Blood pooling in the atria can cause clots that could cause a stroke, Estes says.

A committee of the American College of Cardiology, the American Heart Association and Heart Rhythm Society issued performance measures -- such as prescribing blood thinners such as warfarin -- to help prevent stroke in those with atrial fibrillation.

"There is clear evidence that warfarin reduces the risk of stroke," Estes says.

The measures are published in the Journal of the American College of Cardiology.