class I

1. Class I: Sodium channel blockers
• IA: Prolong repolarization
• Quinidine, procainamide, disopyramide, morcizine
• IB: Shorten repolarization
• Lidocaine, lignocaine, mexiletine, phenytoin
• 1C: Little effect on repolarization
• Encainide, flecainide, propafenone
• 1D: Shorten repolarization
• Ranolazine

4. IA: Quinidine, ajmaline, disopyramide,
procainamide
 Reduce AP conduction velocity and increase ERP.
 Concomitant K + channel block by Class Ia drugs also increases APD.
 Together, these properties reduce reentrant tendency.

6. Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death Guidelines
ESC Clinical Practice Guidelines, 2015
2019 Guidelines on Supraventricular Tachycardia (for the management of patients with)
ESC Clinical Practice Guidelines

7. IB: Lidocaine, mexiletine
• Class IB agents act selectively on diseased or ischemic
tissue, where they are thought to promote conduction
block, thereby interrupting re-entry circuits.
• Shortening of both APD and ERP in normal ventricular
muscle and Purkinje cells, cause prolongation of
ERP and consequently prolongation of
postrepolarization refractoriness in ischemic,
partially depolarized, cells.

8. Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death Guidelines
ESC Clinical Practice Guidelines, 2015

9. Advanced Cardiovascular Life Support 2020

10. EXTENSION OF VAUGHAN WILLIAMS
CLASS I
 Class IC agents have acquired a particularly bad reputation
as a result of the proarrhythmic effects seen in the Cardiac
Arrhythmia SuppressionTrial (CAST) (flecainide) and the
Cardiac Arrest Study Hamburg (CASH) study (propafenone).
 These drugs must be avoided in patients with structural
heart disease.
 Generalized reduction in cardiac excitability with nonspecific
and widespread effects.These include slowed AP
conduction with increasedAPD at high heart rates and
possible reductions in cardiac automaticity.
IC: Propafenone,flecainide

11. Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death Guidelines
ESC Clinical Practice Guidelines, 2015
2019 Guidelines on Supraventricular Tachycardia
(for the management of patients with)
ESC Clinical Practice Guidelines

13. EXTENSION OF VAUGHAN WILLIAMS
CLASS I
ID: Ranolazine

14. Ranolazine
• (MERLIN-TIMI 36) trial, ranolazine significantly lowered non-sustainedVT and
supraventricular tachyarrhythmias in patients with non-ST elevation myocardial
infarction when compared to placebo.
• Early clinical studies have shown that a single dose of 2 g of ranolazine was highly
effective as a “pill-in-the pocket” approach to AF, converting 77% of patients,
without any significant side effects.
• These included patients with structural heart disease, a contraindication for current class
IC agents, and could potentially expand the use of ranolazine.
Scirica, B. M. et al. Effect of ranolazine, an antianginal agent with novel electrophysiological properties, on the incidence of arrhythmias in patients with non-ST-segment-elevation acute coronary syndrome: Results from the metabolic
efficiency with ranolazine for less ischemia in non-ST-elevation acute coronary syndrome-thrombolysis in myocardial infarction 36 (MERLIN-TIMI 36) randomized controlled trial. Circulation 116, 1647–1652 (2007).
Murdock, D. K., Kersten, M., Kaliebe, J. & Larrain, G. The use of oral ranolazine to convert new or paroxysmal atrial fibrillation: A review of experience with implications for possible ‘pill in the pocket’ approach to atrial fibrillation.
Indian Pacing Electrophysiol. J. 9, 260–267 (2009).