A 58-year-old man with a history of anterior wall myocardial infarction presents with frequent premature ventricular contractions (PVCs) on continuous cardiac monitoring. The phase marked **A** in the cardiac action potential diagram represents the rapid depolarization phase driven by voltage-gated sodium channel opening. Which of the following antiarrhythmic drugs would be most appropriate for acute suppression of these ventricular ectopics in the immediate post-MI period?