Class Ic antiarrhythmic
ATC code: C01BC04 (Flecainide)
Brand names
Tambocor
Flecainide blocks fast Nav1.5 sodium channels during phase 0 of the action potential and slows conduction across atria, ventricles, and the His–Purkinje system. It is used for supraventricular tachyarrhythmias, including the «pill-in-the-pocket» approach to paroxysmal atrial fibrillation in patients without structural heart disease. The 1989 CAST trial showed increased mortality in post-myocardial-infarction patients, so flecainide is contraindicated after MI and in structural heart disease. The drug can unmask a Brugada pattern and becomes proarrhythmic during ischaemia.
First line
Class IC antiarrhythmic for pharmacological cardioversion of atrial fibrillation paroxysms and sinus rhythm maintenance in patients without structural heart disease. SEC uses the "pill-in-the-pocket" strategy for infrequent episodes.
Second line
Treats supraventricular tachycardias including AV nodal reentrant and accessory-pathway-mediated forms. SEC requires exclusion of structural heart disease before starting.
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FDA Category C. Primarily used in pregnancy to treat fetal supraventricular tachycardia through maternal administration. Data in pregnancies without fetal arrhythmia are limited; SEC restricts use to vital indications.
Compatible. Hale L3. Transfers into milk (RID about 5%) with minimal clinical exposure of the infant. Infant ECG monitoring is advised during prolonged maternal therapy.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Flecainide is evaluated for the following indications with varying evidence strength: Atrial fibrillation (evidence tier B), Supraventricular tachycardia (evidence tier B). See the full indication matrix with dosing and citations above on this page.
Common side effects of Flecainide (≥ 1 in 100): Dizziness, Visual disturbances, Nausea, Fatigue, Tremor. See the Safety section for uncommon and serious reactions.
FDA category C. FDA Category C. Primarily used in pregnancy to treat fetal supraventricular tachycardia through maternal administration. Data in pregnancies without fetal arrhythmia are limited; SEC restricts use to vital indications.
Compatible. Hale L3. Transfers into milk (RID about 5%) with minimal clinical exposure of the infant. Infant ECG monitoring is advised during prolonged maternal therapy.
Flecainide is contraindicated in: Hypersensitivity to flecainide; Heart failure NYHA class III–IV; Asymptomatic ventricular ectopy or non-sustained ventricular tachycardia; History of myocardial infarction (CAST trial findings); Cardiogenic shock. Full list in the Safety section.