Antiarrhythmic drug mechanisms and the Vaughan Williams classification
How each Vaughan Williams class changes the cardiac action potential, use dependence and reverse use dependence, why flecainide needs an AV nodal blocker and a normal heart, the CAST lesson, and the 2018 modernised classification.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The Vaughan Williams scheme (1970s) groups drugs by main action: I Na⁺ channel block, II beta-blockade, III K⁺ channel block, IV L-type Ca²⁺ channel block.
- Most drugs act in more than one class. Amiodarone has all four actions; sotalol is II and III.
- Lei et al. (Circulation 2018) modernised the scheme into classes 0 to VII, adding HCN blockers, autonomic modulators, ryanodine receptor block and upstream therapy.
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Sources
- Modernized classification of cardiac antiarrhythmic drugsCirculation (Lei, Wu, Terrar and Huang, 2018;138:1879-96), 2018
- Therapeutic Guidelines: CardiovascularAU/NZTherapeutic Guidelines Ltd
- Australian Medicines HandbookAU/NZAustralian Medicines Handbook Pty Ltd, 2026
- Preliminary report: effect of encainide and flecainide on mortality in a randomized trial of arrhythmia suppression after myocardial infarction (CAST)New England Journal of Medicine (Cardiac Arrhythmia Suppression Trial Investigators, 1989;321:406-12), 1989
- 2024 ESC Guidelines for the management of atrial fibrillationEuropean Society of Cardiology, 2024
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy