<prompt> Which of the following agent is a class c antiarrhythmic drugQuinineAmiodaronePropranololLignocaine  <response>: Refer kDT 7e 529 Class III agents have the potential to prolong the QT interval of the EKG, and may be proarrhythmic more associated with development of polymorphic VT. Class III agents include: bretylium, amiodarone, ibutilide, sotalol, dofetilide, vernakalant and dronedarone 