Flecainide

Classification:

Class IC – Sodium (Na⁺) channel blockers

Propafenone – slows conduction in atrial myocardium and is also a non-selective beta-blocker
Flecainide – slows conduction in atrial myocardium

Diagram of the effect of flecainide as a class IC antiarrhythmic illustrating use-dependent sodium channel blockade, reduced myocardial excitability, and pharmacological cardioversion of atrial fibrillation to sinus rhythm.

Mechanism:

Slows conduction in the myocardium, reduces excitability and automaticity

Inhibits the non-nodal action potential (in the working myocardium)

Use-dependent (effect increases at heart rate > 90/min.)

More pronounced effect than propafenone

Effect on AF:

Maintenance of sinus rhythm – prevents recurrence of atrial fibrillation (AF)
Cardioversion of AF to sinus rhythm – termination of an AF episode and restoration of sinus rhythm

“Pill-in-the-pocket” strategy – single oral dose of flecainide taken at home at the onset of an AF episode.

The goal is restoration of sinus rhythm

Flecainide and atrial fibrillation (AF)
Brand names
Amarhyton, Flekainid, Tambocor, Apocard, Almarytm, Flécaïne, Flecaine, Flecadura, Juneflecad
Indications
Acute cardioversion of AF to sinus rhythm “Pill-in-the-pocket” strategy Maintenance of sinus rhythm
Dosing
Acute cardioversion of AF to sinus rhythm (intravenous) 1–2 mg/kg – approximately 70–150 mg administered intravenously over 10 minutes Acute cardioversion of AF to sinus rhythm (oral) – “pill-in-the-pocket” strategy 200 mg (< 70 kg) – immediate-release formulation, single dose 300 mg (> 70 kg) – immediate-release formulation, single dose Chronic rhythm control – maintenance of sinus rhythm (oral) 50–150 mg twice daily Start with 50 mg twice daily and increase the dose every 4 days by 100 mg per day (maximum 300 mg per day)
Onset of action
< 6 hours (intravenous) < 8 hours (oral)
Effect
Time to conversion to sinus rhythm and success rate < 6 hours – 52–95 % (intravenous) < 3 hours – 50–60 % (oral) 3–8 hours – 75–85 % (oral) Maintenance of sinus rhythm (paroxysmal or persistent AF) at 1 year 50–65 %
Duration of action
6–12 hours (intravenous) 12–24 hours (oral) – immediate-release formulation 24 hours (oral) – prolonged-release formulation
Contraindications
Atrial flutter (flecainide must not be administered for cardioversion) Second- or third-degree AV block Bradycardia (< 50/min.) Hypotension (< 90 mmHg) Severe electrolyte imbalance (Na⁺, K⁺, Mg²⁺) Myocardial infarction (within the last 3 months) Cardiogenic shock Ejection fraction < 40 % Severe structural heart disease Brugada syndrome Sick sinus syndrome (without a pacemaker) Severe hepatic dysfunction Allergy to flecainide

Patient monitoring after initiation of flecainide:

Discontinue if contraindications develop
Discontinue or reduce the dose if adverse effects occur

Patient monitoring after initiation of flecainide
Time since initiation	What to monitor	Reason for treatment discontinuation
1 week	ECG (QRS, PR interval) Blood pressure	QRS > 120 ms or prolongation > 25 % Bradycardia < 50/min Hypotension < 90/60 mmHg Brugada pattern on ECG
1 month	ECG (QRS, PR interval)	QRS > 120 ms or prolongation > 25 % Brugada pattern on ECG
6–12 months	ECG (QRS, PR interval) Laboratory tests Echocardiography Holter ECG as needed	Ejection fraction < 40 % QRS > 120 ms or prolongation > 25 % Brugada pattern on ECG Severe laboratory abnormalities

Adverse effects:

Very common (> 10 %):

Dizziness
Visual disturbances
Ventricular arrhythmias

Common (1–10 %):

AV block (first- and second-degree)
1:1 conducted atrial flutter
Heart failure
Bradycardia
Chest pain
Oedema
Nausea
Depression
Fatigue
Headache
Tremor
Tinnitus
Sweating
Paresthesia
Skin rash

Less common (< 1 %):

Third-degree AV block
Alopecia
Urticaria
Decreased libido
Taste disturbance
Flatulence
Impotence
Urinary retention
Granulocytopenia
Abnormal dreams
Euphoria
Neuropathy
Seizures
Speech disorder
Arthralgia
Myalgia

Propafenone and flecainide both belong to Class IC anti-arrhythmic drugs, but they are distinct molecules.

Therefore, their properties differ partially.

Propafenone vs. flecainide and atrial fibrillation (AF)
Property	Propafenone	Flecainide
Mechanism of action	Na⁺ channel blockade + mild beta-blocking effect	Na⁺ channel blockade, without beta-blocking effect
Effect on AV node	Mild slowing of conduction (via beta-blockade)	Virtually no direct effect
Use in AF	Acute cardioversion, maintenance of sinus rhythm, partial rate control	Acute cardioversion, maintenance of sinus rhythm (combination with BB/NDHP CCB is recommended)
Efficacy at 1 year	~40–60 % maintenance of sinus rhythm	~50–65 % maintenance of sinus rhythm
Effect on heart rate	Reduces (due to beta-blockade)	No significant effect
Use-dependence	Less pronounced; partially attenuated by beta-blocking effect	Pronounced; marked QRS prolongation at higher heart rates
Adverse effects	Nausea, metallic taste, bradycardia, hypotension	Dizziness, visual disturbances