This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'Drug used for atrial fibrillation and atrial flutter is \nSelect and explain. \nA. Verapamil, B. Digitalis, C. Quinidine, D. Diphenylhydantoin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: For AF, digoxin can be used- it decreases ventricular rate in AF Verapamil decreases conduction velocity and increases the refractory period of the AV node and so used in PSVT. REF.Essentials of Pharmacology KD Tripathi 8th ed.', 'role': 'assistant'}]