Class II drugs are β-adrenergic receptor antagonists.
These agents have the ability of decreasing Phase 4 depolarization thus suppresses the automaticity, causing a prolonged AV conduction and decreased cardiac rate and contractility.
Class II drugs are used in the treatment of tachycardia due to promoted activity of sympathetic system.
They are also useful in the treatment of atrial flutter and fibrillation.
They are used in AV nodal re-entrant tachycardia.