Effect of intravenous flecainide on atrial vulnerability in man.

Sixteen patients were investigated by means of programmed atrial stimulation at 2 different driving rates: 100/min and 120/min. All patients had an increased atrial vulnerability at both driving rates. After the administration of intravenous flecainide (1 mg/kg bodyweight as a bolus, followed by the same amount infused over a period of 20 minutes), the increased vulnerability was abolished in 11 and 9 patients, respectively. In the remaining patients the rate of induced atrial tachyarrhythmia decreased. These findings correlate with a significant prolongation of the effective refractory period of the right atrium and a corresponding significant shortening of its relative refractory period. It is concluded that flecainide may be effective in the treatment of atrial arrhythmias in humans.