New guidelines from the American College of Cardiology state that risk factors for stroke should be the major determinant in deciding whether to start anticoagulation therapy for patients with atrial fibrillation. The guidelines were released jointly with the American Heart Association and the European Society of Cardiology.

The previous guidelines, published in 2001, recommended using several patient characteristics -- age, gender, heart disease risk and concurrent conditions - - to decide whether to start anticoagulation therapy. The new approach recommends that the risk for stroke should be the main factor, said Valentin Fuster, MD, PhD, co-chair of the guidelines writing committee.

"We focused on stroke risk because atrial fibrillation is associated with increased long- term risk for stroke," Fuster said. "About 15 percent to 20 percent of strokes occur in people with atrial fibrillation, and those strokes are especially large and disabling. Incorporating existing recommendations on anti-clotting therapy from the stroke primary prevention guidelines will streamline patient care and make recommendations clearer for physicians."

In the United States and Europe, hospital admissions for atrial fibrillation have increased by 66 percent during the last 20 years.

The revised guidelines recommend daily aspirin therapy (81-325 mg) to guard against blood clots in patients with no stroke risk factors. Aspirin or warfarin is recommended for patients with one "moderate" risk factor (over age 75 years, hypertension, heart failure, impaired left ventricular systolic function, or diabetes). Warfarin is recommended for people with any "high" risk factor (previous stroke, transient ischemic attack, systematic embolism or prosthetic heart valve) or more than one moderate risk factor.

According to co-chair Lars E. Ryden, MD, PhD, professor emeritus at Karolinska Institutet in Stockholm, Sweden, the guidelines help physicians prioritize the objectives of patient care according to the following steps: 1) controlling heart rate, 2) preventing clots, and, if possible, 3) correcting the rhythm disturbance.

Also new in the guidelines, catheter ablation is considered "a reasonable alternative to drug therapy to treat atrial fibrillation in patients with little or no left atrial enlargement, and in whom drug treatments did not stop the rhythm disturbance," Fuster said.

Depending on symptoms, controlling the heart rate may be the reasonable therapy in elderly patients with persistent atrial fibrillation who have hypertension or heart disease, according to the joint statement.

For people under age 70 years, especially those with recurrent atrial fibrillation and no evidence of underlying heart disease, rhythm control may be the preferred approach, starting with drugs and by means of catheter ablation if medication fails to stop the attacks. Both Fuster and Ryden emphasized that "Regardless of the approach, the need for anti-clotting therapy should still be based on stroke risk and not on whether proper heart rhythm is maintained."