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The most common cardiac rhythm disorder, atrial fibrillation (AF) affects an estimated 2.3 million Americans and is becoming more widespread as the population ages.
The American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) published practice guidelines for the condition in 2006. In the years since, several new drugs have received approval for use in patients with the disorder, and additional evidence has become available to support or modify existing treatments. This year the AACF and the AHA published two new updates, entitled Focused Updates on the Management of Patients with Atrial Fibrillation.
Whether AF can be managed in primary care depends on factors including patient age and comorbidity, symptoms and the complexity of the condition.
“As a cardiologist, stroke is the primary thing I worry about in AF. If you can keep the patient from having a stroke, you are two-thirds of the way home, and the primary-care clinician can often do that,” said L. Samuel Wann, MD, director of cardiology at Wisconsin Heart Hospital in Milwaukee, and chair of the group that wrote the updates.
Several of the changes simplify treatment or apply to areas of management that are particularly germane to general practice.
Accelerated ventricular heart rate — at rest and during exercise — is a frequent concern in AF, and one commonly endorsed goal has been “strict rate control,” which entails keeping heart rate <80 bpm at rest and <110 bpm during moderate exercise.
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The ACCF/AHA update sites several large recent trials in it’s conclusion that this approach is no more beneficial than “lenient control” — maintaining a resting heart rate <110 bpm — for patients who have no or minimal symptoms and stable ventricular function. In this population strict control appeared to have no advantage in symptoms, quality of life, or such clinical endpoints as cardiac events, hospitalization or death.
In practical terms this means a simpler less aggressive approach to rate control for most patients. “There is no reason for repeated Holter monitoring or exercise tests or for adding drugs or increasing doses in pursuit of an arbitrary cutoff,” Wann said.
But “lenient control” does not mean “no rate control,” he added. Pronounced tachycardia can have detrimental cardiac effects over the long term, including cardiomyopathy, and patients who remain symptomatic despite lenient control might well be referred to a cardiologist or electrophysiologist for further evaluation and treatment.
Expanded anticoagulation options
Oral anticoagulation to prevent thromboembolism is indicated for AF patients with a history of stroke or transient ischemic attack and should be considered for those otherwise at risk of stroke.
In the 2006 guidelines, this essentially meant warfarin (Coumadin). The first of the 2011 focused updates recommends another regimen —aspirin combined with clopidigrel (Plavix)—as a reasonable alternative for patients in whom anticoagulation with warfarin is considered unsuitable.1
“Warfarin is a tough drug to give, and a sizeable number of patients won’t take it,” Wann warned. “They don’t like going back and forth to have their INR [international normalized ratio] checked. There are also dietary restrictions.” Bruising and bleeding can be problematic as well.
Clinicians should keep in mind that while the aspirin-clopidigrel combination is more effective than aspirin alone in preventing vascular events in AF patients, it is considerably inferior to warfarin.