Atrial Pacing for Termination and Prevention of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with substantial morbidity and mortality. Present treatment strategies are aimed at termination of AF and prevention of AF recurrence using antiarrhythmic drugs or heart rate control drugs. Drugs are not always well tolerated, so atrial pacing as a strategy for prevention of atrial tachyarrhythmias is being explored. The AT501 pacemaker has both "prevention" and "treatment" algorithms for atrial tachyarrhythmias. The investigators wish to determine whether these special features, over the long term, decrease the amount of time the person experiences AF.