Two Antiarrhythmic Class Systems: What It Does vs How Well It Works When people talk about “antiarrhythmic classes,” they often mean two completely different things—and mixing them up can be dangerous. In this quick ACLS review, we break down: ✅ Mechanism-of-action classes (what the drug actually does) Class I: sodium channel inhibitors Class II: beta blockers Class III: potassium channel inhibitors Class IV: calcium channel blockers (push slow) ✅ AHA recommendation classes (how strongly the dru