Which medication is a beta-blocker with class III antiarrhythmic properties used for AF?

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Combining beta-adrenergic blocking with class III potassium channel blockade is what makes this drug stand out for atrial fibrillation. The beta-blocking action slows AV nodal conduction and reduces adrenergic triggers that can promote AF, while the class III effect prolongs repolarization, increasing the refractory period and helping maintain sinus rhythm. Amiodarone does have class III activity and some beta-blocking–like effects, but it is not primarily categorized as a beta-blocker; dofetilide is a pure class III blocker with no beta-blocking action; quinidine is class IA, not class III. Therefore, the drug that best fits both beta-blocker and class III antiarrhythmic properties used for AF is the one that uniquely combines both actions.