Acute sildenafil administration decreases the susceptibility to induced atrial fibrillation in sheep

Sildenafil has been shown to decrease ventricular arrhythmias. We investigated whether sildenafil could similarly decrease atrial fibrillation (AF) burden through direct effects on atrial electrophysiology. In vivo electrophysiological studies were performed in 12 anaesthetised sheep before and after 10 mg intravenous sildenafil. Sildenafil decreased AF vulnerability by decreasing both AF incidence and duration. The antiarrhythmic actions of sildenafil were associated with increases in atrial effective refractory period and atrial wavelength, together with a decrease in alternans magnitude which were expected to limit both AF duration and incidence respectively. The antiarrhythmic effects of acute sildenafil should be confirmed in man.