Flecainide is a class IC antiarrhythmic drug that acts by blocking sodium channels and has no effect on the action potential. Flecainide is frequently used to maintain sinus rhythm in patients with paroxysmal or persistent atrial fibrillation.

Significant coronary artery disease is a contraindication to its use as this increases the risk of proarrhythmia and sudden cardiac death. These agents must be used in combination with an AV blocking agent in order to prevent rapid atrial fibrillation or atrial flutter conduction (1:1 conduction) through the AV node resulting in very fast ventricular rates if a breakthrough episode occurs since class IC drugs also act to increase AV nodal conduction. These drugs may be proarrhythmic in the setting of left ventricular hypertrophy (wall thickness > 1.4 cm).

Flecainide can be used with a “pill-in-the-pocket” approach. If documented to be successful and safe while hospitalized, flecainide can be used on an as-needed basis in the outpatient setting. Note that propafenone (another class IC agent) is hepatically cleared (not recommended with liver disease) while flecainide is renally cleared.