The current evidences indicate that ~30% patients with sick sinus syndrome(SSS) would develop persistent atrial fibrillation (AF) after a long term pacing therapy. However, the accurate influence of antiarrhythmic drugs on the AF is still not well defined. The purpose of the study is to assess the therapeutic effects of various antiarrhythmic drugs (Amiodarone, Sotalol and Propafenone) on the long term management of AF in SSS patients with AF, including the reduced AF burden (duration and episodes) and persistent AF free survival rate. All patients will be followed up for 12 months.