Narrow complex tachycardia afib aflutter management

A 60-year-old patient presents with new onset atrial fibrillation and a heart rate of 160 bpm. They have no signs of heart failure and are hemodynamically stable. Which of the following is the most appropriate initial treatment?

1: Immediate synchronized DC cardioversion
2: Rate control with beta-blockers
3: Anticoagulation with warfarin
4: Pharmacologic cardioversion with flecainide