A 68-year-old man presents with palpitations. ECG shows a regular broad-complex tachycardia at 180 bpm. He is alert, BP 104/68 mmHg, with a history of ischaemic heart disease. Most appropriate initial management?
AIV adenosine 6 mg rapid bolus
BIV amiodarone 300 mg over 20โ60 minutes
CImmediate synchronised DC cardioversion