Am in my second month of taking Metoprolol to control atrial fibr...

Am in my second month of taking Metoprolol to control atrial fibrillation. Have been increasingly dealing with disturbingly vivid dream, headaches, slight nausea, abdominal discomfort and overall achiness. What is an alternative med to treat atrial fibrillation? I have glaucoma and a cardiac pacemaker for complete heart block. All suggestions welcomed. I'd like to dump the Metroprolol but appreciate that since starting to take it, I've had no problems with fibrillation (which my pacemaker isn't designed to control).