Class IC Antiarrhythmics

Flecainide and propafenone are class 1c antiarrhythmics due to their ability to slow conduction.  Flecainide blocks sodium channels and potassium channels, which decreases the rate of phase 0 depolarization in Purkinje fibers.  Flecainide also slowly dissociates from sodium channels.  Propafenone is also a sodium channel blocker with similar effects but also has beta antagonist properties.   Caution with use in heart failure, bradycardia or SA node dysfunction, and post-myocardial infarction.

Class Drugs

• Flecainide

• Propafenone

Class Mechanism of Action

Sodium Channel Blockade

• Slow dissociation from sodium channels

• Suppresses Phase 0 upstroke in Purkinje fibers and in cardiac tissue, which results in slowed conduction

• Strong Effect

---

Class IC Antiarrhythmics Diagram

Class Applications

Treatment/Maintenance of sinus rhythm in patients with atrial fibrillation and atrial flutter

Ventricular arrhythmias

Class Adverse Effects

• Contraindicated in patients with structural heart disease

Heart failure

• Ventricular hypertrophy

• Coronary artery disease

• Blurry vision

• Dizziness

Drug Table

Drug Name	Application	Comments	Image
Flecainide		Mechanism of Action; Also blocks potassium channels; Increases action potential duration	"Flea" "Cane"
Propafenone		Mechanism of Action; Beta-blocking effects; Adverse Effects; Bronchospasm in asthma due to the beta-blocking effects	"Propane tank" "Telephone"