I've had a pacemaker since 1994, heart was stopping on it's own. Started going into atrial fibrilation over a year ago when I was dehydrated. Stay hydrated and it doesn't happen, at least not yet. They've got me on Warfarin for that. The warfarin is fun, it weakens my veins and gives me "rhoids" that bleed. My pacemaker was recording heart rates around 200, so the cardiologist put me on Metoprolol Tartrate.