PHYSICIAN ATTITUDES TOWARD THE USE OF TYPE-IC ANTIARRHYTHMICS AFTER THE CARDIAC-ARRHYTHMIA SUPPRESSION TRIAL (CAST)

In the mid 1980s, 2 compounds considered to be class IC1 antiarrhythmic agents, flecainide and encainide, received approval in the U.S. for treating symptomatic, or life-threatening ventricular arrhythmias, or both. Despite a notable proarrhythmia risk,1-12 their use grew because of high efficacy, low organ toxicity, and otherwise excellent patient tolerance. In August 1989, however, the Cardiac Arrhythmia Suppression Trial (CAST)13,14 high-lighted the proarrhythmic risk of these 2 agents and the Food and Drug Administration (FDA) responded by re-labeling these drugs. They are now approved in the U.S. only for the treatment of lethal ventricular tachyarrhythmias. FDA sanctions and specific package labeling, however, have never guaranteed that a drug will be used according to such sanctions and instructions. Physicians are free to exercise therapeutic judgment, assuming an appropriate rationale and support from the medical literature. Given the favorable efficacy, convenience and side effect profiles of encainide and flecainide apparent before CAST, we hypothesized that their use might continue despite the recent FDA guidelines. To test this belief, we formulated a questionnaire concerning the use of class IC agents after CAST. We assumed this information would interest drug regulators, pharmaceutical manufacturers, investigators and those physicians in practice who prescribe or avoid IC agents without certainty as to peer behavior. © 1990.