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
Drug of choice for paroxysmal supraventricular tachycardia is: 
Select and explain. 
A. Verapamil, B. Diltiazem, C. Digoxin, D. Phenytoin
A: Verapamil
Answer: A: Verapamil 
Explanation: Verapamil decreases conduction velocity and increases the refractory period of the AV node, thus useful in PSVT. It is a CCB, Class 4 antiarrhythmic drug Adenosine and magnesium sulfate can also be used for PSVT REF: Essentials of Pharmacology KD Tripathi 8th ed.