Measures of drug efficacy in treating atrial fibrillation

Atrial fibrillation (AF) tends to recur in at least one half of the patients being treated with an antiarrhythmic agent. However, if the patient being treated is appropriately anticoagulated, and if during recurrence the ventricular response rate is controlled, a recurrence rarely requires emergent treatment. Rather, the AF recurrence can most often simply be considered a clinically important nuisance. Therefore, recurrence of AF during antiarrhythmic drug therapy should not be considered drug failure per se. Instead, the frequency and severity of recurrence constitute the measure of efficacy. Occasional recurrence may be clinically acceptable and preferable to persistent AF or frequent episodes of paroxysmal AF. Because occasional recurrence of AF should not be considered failure of drug therapy, simple outpatient cardioversion of the AF with restoration of sinus rhythm is recommended should recurrence occur and the AF persist. Simple therapies, such as acute cardioversion to restore sinus rhythm, should be considered a part of the expected long-term therapy of the patient with AF. Finally, the drug of choice should be one that is well tolerated, easy to take (preferably only once or twice a day), and has the fewest potential side effects, particularly serious adverse effects.