New guidelines for managing patients with atrial fibrillation sharpened the definition of who should get antithrombotic prophylaxis and elevated the role for catheter ablation for this increasingly common disorder.
The atrial fibrillation (AF) guidelines, published in August by a committee assembled by the American College of Cardiology, the American Heart Association, and the European Society of Cardiology, “simplifies therapy and expands the indications for anticoagulation,” said Dr. Lars Rydén, a cardiologist and professor emeritus at the Karolinska Institute, Stockholm, and cochair of the guidelines committee.
A revision of guidelines first released in 2001, “the new guidelines focus more on [each patient's] total risk for thromboembolism than the previous guidelines, and bring in a number of factors that increase the risk,” Dr. Rydén said in an interview. “We're telling people to look at a patient's total risk when deciding on anticoagulation. This risk may change over time, and there is a need to reevaluate patients.” The revision also makes the AF guidelines more consistent with other guidelines that deal with antithrombotic treatment.
The new guidelines call for thromboembolism prophylaxis with aspirin, at a dosage of 81–325 mg/day, for all patients with AF who are not receiving warfarin (J. Am. Coll. Cardiol. 2006;48:854–906). The guidelines also identify five types of moderate risk factors that identify patients who could either receive aspirin or are candidates for prophylaxis with warfarin, with a target international normalized ratio (INR) of 2.5 and a range of 2.0–3.0.
Another three clinical findings were defined as high-risk factors that each mandate prophylaxis with warfarin as does having two or more moderate risk factors. (See box.) The INR target is the same.
The guidelines also identified four less-validated or weaker risk factors that don't warrant changing the basic aspirin regimen. These four factors are female gender, an age of 56–74 years, the presence of coronary artery disease, and the presence of thyrotoxicosis.
Universal prophylaxis with aspirin or warfarin marks a significant change in what's been standard practice in the United States, Europe, and elsewhere. “Presently, there is huge undertreatment in clinical practice for decreasing the risk of thromboembolism in patients with AF,” Dr. Rydén said. “Proper management according to the guidelines will prevent a number of strokes and other manifestations of thromboembolism.”
Another noteworthy change from the 2001 guidelines was the larger role given to catheter ablation of arrhythmogenic foci. The new guidelines say ablation is reasonable “when pharmacological therapy is insufficient or associated with side effects.”
Setting catheter ablation as a second-line therapy reflected the rapid acceptance of the technique since it was first reported in the late 1990s.
The 2001 guidelines said that catheter ablation had produced promising results but had not yet been widely applied, and the method was listed as a tertiary option or lower.
“The guidelines underline that [ablation] is an interesting and very promising method, but there is still a need for much more exact information on the absolute benefits, risk/benefit ratio, and long-term complications,” Dr. Rydén said.
Dr. Rydén said that a reasonable trial of pharmacotherapy would involve trying at least two different drugs or drug combinations, and giving each a reasonable interval to work. “At present, ablation is a technique [used] when other treatment modalities are contraindicated, stopped due to side effects, or have unsatisfactory value.”
The new guidelines also provide a comprehensive sequence for dealing with AF patients.
“It is probable that patients with AF are sometimes subjected to many attempts to reestablish sinus rhythm. But many patients would do as well with proper rate control,” Dr. Rydén said.
The guidelines say that at least one attempt to restore sinus rhythm is reasonable, but that further attempts should be based on the severity of arrhythmia-related symptoms balanced against the risk of using antiarrhythmic drugs.
Transesophageal echocardiographic image of a mobile and protruding thrombus (arrow). J. Am. Coll. Cardiol. 2001;37:691–704, ©2001; used by permission from the American College of Cardiology Foundation