Paroxysmal & Refractory Atrial Fibrillation

A. Recurrent Paroxysmal Atrial Fibrillation

It is now well established that patients with recurrent paroxysmal atrial fibrillation are at similar stroke risk as those who are in atrial fibrillation chronically. While these episodes may be apparent to the patient, many are not recognized and may be totally asymptomatic. Thus, ambulatory electrocardiographic monitoring or event recorders are indicated in those in whom paroxysmal atrial fibrillation is suspected. Antiarrhythmic agents are usually not successful in preventing paroxysmal atrial fibrillation episodes. However, immediate self-administered treatment with an antiarrhythmic agent (experience is perhaps greatest with propafenone, 300 mg orally, repeated once after 2-3 hours if necessary) may interrupt symptomatic episodes, and chronic use of a beta-blocker or rate-slowing calcium channel blocker may reduce the severity of symptoms. In any case, chronic anticoagulation is indicated except in those who are under 60-65 years of age and have no additional stroke risk factors.

B. Refractory Atrial Fibrillation

Because of trial results indicating that important adverse clinical outcomes (death, stroke, hemorrhage, heart failure) are no more common with rate control than rhythm control, atrial fibrillation should generally be considered refractory if it causes persistent symptoms or limits activity.

This is much more likely in younger individuals and those who are very active or engage in strenuous exercise. Even in such individuals, two-drug or three-drug combinations of a beta-blocker, rate-slowing calcium blocker, and digoxin usually can prevent excessive ventricular rates, though in some cases they are associated with excessive bradycardia during sedentary periods. If rapid ventricular rates persist, amiodarone may be substituted for or added to these agents.

If no drug works, radiofrequency AV node ablation and permanent pacing ensure rate control and may facilitate a more physiologic rate response to activity. There is growing experience with focal ablation of foci in the pulmonary veins that initiate atrial fibrillation, following which sinus rhythm may be restored or maintained. A surgical approach called the Maze procedure can also be used to eliminate the multiple reentry circuits that cause atrial fibrillation, and implantable atrial defibrillators can be used to convert paroxysmal episodes. The role of these latter procedures is limited, however.

Preferences:

_{Albers GW et al: Antithrombotic therapy in atrial fibrillation. Chest 2001;119:194S.}

Chugh SS et al: Epidemiology and natural history of atrial fibrillation: clinical implications. J Am Coll Cardiol 2001;37:371.

Falk RH: Atrial fibrillation. N Engl J Med 2001;344:1067.