Amiodarone for refractory automatic atrial tachycardia: observations on the electrophysiological actions of amiodarone.

A patient with automatic atrial tachycardia refractory to all conventional therapies is described. Amiodarone controlled the tachycardia by causing a progressive decrease in the rate of discharge from the atrial focus. We conclude that 1) amiodarone was effective therapy for automatic atrial tachycardia, avoiding the need for nonmedical therapy; and 2) amiodarone appeared to act by decreasing spontaneous automaticity.