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New guidelines take an evidence-based medicine approach to atrial fibrillation

Atrial fibrillation (AFIB), affecting 0.4% of the total population, is a supraventricular tachyarrhythmia caused by simultaneous discharge of multiple atrial foci. It is the most common sustained arrhythmia encountered in clinical practice. Because the prevalence of AFIB increases with advancing age, as many as 1% of individuals over age 60 may be affected, and up to 6% of those over 80 years may present with signs or symptoms.

The most common complaint from patients with AFIB is cardiac palpitation, although fatigue, dyspnea, and dizziness are also reported. Some patients, however, despite an irregular heart rhythm, are asymptomatic. And because diverse causes underlie the etiology of AFIB—and numerous diseases affecting cardiac tissues, such as hypertension, congestive heart failure, and valvular heart disease, are often present concomitantly with AFIB—its treatment may be quite complex.

Because AFIB treatment is so complicated and patient-specific, new practice guidelines were recently established by the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology (ESC). Their purpose is to offer assistance in clinical decision making by describing a range of accepted approaches for diagnosing, managing, and preventing AFIB and associated conditions. The guidelines are the first comprehensive practice recommendations on AFIB to be published in several years.

Several algorithms for pharmacologic interventions are included in the guidelines for managing patients with different types of AFIB. The algorithms can be followed to determine not only if treatment is required but what type of medication should be considered. For example, patients with newly discovered AFIB may or may not require antiarrhythmic therapy, depending on whether the irregular rhythm is paroxysmal or persistent. For paroxysmal AFIB, antiarrhythmic therapy may be delayed, but anticoagulation may be indicated. In contrast, persistent AFIB with disabling symptoms may require pharmacologic intervention to treat the arrhythmia, to maintain cardiac rate control, and for anticoagulation. Other algorithms in the new guidelines offer a step-by-step process for determining which antiarrhythmic drugs are best for individuals in the face of other types of heart disease.

"The new guidelines are well done, very complete, and up to date," said Jerry Bauman, Pharm.D., FCCP, FACC, professor and interim head of the department of pharmacy practice at the University of Illinois. One thing that sets them apart from other documents published previously is that "the authors take a firm evidence-based approach" toward clinical recommendations. The suggestions in the new ACC/AHA/ ESC guidelines are based primarily on published data and are ranked according to whether the data were derived from multiple randomized clinical trials, nonrandomized observational studies, or expert opinion.

Bauman also noted the prominent place dofetilide (Tikosyn, Pfizer) received in the guidelines. According to Judy Cheng, Pharm.D., associate professor of pharmacy practice at Arnold & Marie Schwartz College of Pharmacy & Health Sciences at the Long Island University, "Dofetilide is the only new antiarrhythmic" to be added since the last guidelines. "The new guidelines help to establish the type of patient population for which the drug is best suited. Dofetilide is one of the few drugs that can be used in heart failure patients," she said.

While both Bauman and Cheng are pleased with the new AFIB practice guidelines, they believe that the current standards of practice for pharmacologic therapy are already in line with them. However, the guidelines may result in changes in the surgical management of AFIB, particularly with respect to surgical ablation. Atrioventricular nodal ablation and permanent pacemaker implantation may be considered for patients experiencing symptoms due to a rapid ventricular rate during AFIB that is not adequately controlled with antiarrhythmic or negative chronotropic medications.

A full text version of the guidelines is available on the American College of Cardiology Web site located at www.acc.org/clinical/statements.htm and will also be published in the mid-October issue of the European Heart Journal.

Kelly Dowhower Karpa, R.Ph., Ph.D.

The author is a writer in the Philadelphia area.

Kelly Karpa. New guidelines take an evidence-based medicine approach to atrial fibrillation.

Drug Topics

2001;19:32.