There are five main classes in the Vaughan Williams classification of antiarrhythmic agents:
Class I agents interfere with the sodium (Na+) channel.
Class II agents are anti-sympathetic nervous system agents. Most agents in this class are beta blockers.
Class III agents affect potassium (K+) efflux.
Class IV agents affect calcium channels and the [AV node].
Class V agents work by other or unknown mechanisms.
