A 62-year-old man with a history of ischemic cardiomyopathy (EF 30%) is brought to the emergency department with sudden onset palpitations, diaphoresis, and near-syncope. On arrival, his blood pressure is 80/50 mm Hg, heart rate 180/min, and he appears diaphoretic and lethargic. ECG demonstrates a wide-complex tachycardia at 180/min consistent with monomorphic ventricular tachycardia. He has a palpable but weak carotid pulse and no signs of cardiac arrest. Which of the following is the most appropriate next step in management?