A 52 yr old female presented with breathlessness and palpitations since past 3 days having past history of CHD. CABG was done 15 yrs back. Patient stopped all medication few yrs back. No history of DM and HTN. ECG reveals no p waves.

Pulse rate recorded by pulse oximeter is 140 bpm and spo2 98%. What is the further management apart from starting her on anticoagulants? Which is the preferred antiarrhythmic agent? Is it essential to start her on antiarrhythmic ? If it's essential whether amiodarone can be preferred.