My 72 Year Old Brother Has Been Taking Coreg For

My 72 year old brother has been taking Coreg for Atrial Fibrillation and it (plus an oblation procedure) kept him in Sinus rhythm for 3 years. He has recently begun experiencing episodes of falling out of Sinus rhythm and his doctor prescribed Valsartan (Generic for Diovan) two days ago. I am reading that Valsartan is normally used for treatment of high blood pressure and/or heart failure. Is it also commonly used to help control irregular heart beat?