<prompt> Beta blockers are antiarrhythmic agents of class1111111V  <response>: Refer kDT 6e p 511 The five main classes in the Vaughan Williams classification of antiarrhythmic agents are: Class I agents interfere with the sodium Na channel. Class II agents are anti-sympathetic nervous system agents. ... Class III agents affect potassium K efflux. Class IV agents affect calcium channels and the AV node. 