What is the recommended use and dosage of flecainide for treating irregular heartbeat?

Flecainide for Treating Irregular Heartbeat: Recommended Use and Dosage

Flecainide is recommended for treating supraventricular tachyarrhythmias at an initial dose of 50 mg twice daily, with gradual titration up to a maximum of 300 mg/day, and should only be used in patients without structural heart disease. 1, 2

Patient Selection

Flecainide is appropriate for:

• Paroxysmal supraventricular tachycardia (PSVT) 3
• Paroxysmal atrial fibrillation (PAF) 3, 2
• Atrioventricular re-entry tachycardia (AVRT) 3

Absolute Contraindications 1

• Structural heart disease
• Coronary artery disease
• Reduced left ventricular ejection fraction
• Cardiogenic shock
• Sinus or AV conduction disease (without pacemaker)
• Brugada syndrome
• Atrial flutter (unless with AV nodal blocking therapy)
• Severe renal or hepatic dysfunction

Dosing Protocol

Initial Dosing

• Start with 50 mg every 12 hours 1, 2
• For sustained ventricular tachycardia (VT): 100 mg every 12 hours (initiate in-hospital with rhythm monitoring) 2

Dose Titration

• Increase in increments of 50 mg twice daily 2
• Allow at least 4 days between dose increases (due to long half-life of 12-27 hours) 2
• Titrate until efficacy is achieved or maximum dose is reached 2

Maximum Recommended Doses

• PSVT/PAF: 300 mg/day (150 mg twice daily) 2
• Sustained VT: 400 mg/day (rarely exceed 300 mg/day) 2

Special Populations

• Severe renal impairment (CrCl ≤35 mL/min): Initial dose 100 mg once daily or 50 mg twice daily 1, 2
• When co-administered with amiodarone: Reduce flecainide dose by 50% 1
• Pediatric patients <6 months: 50 mg/m² body surface area daily (divided into 2-3 doses) 1, 2
• Pediatric patients >6 months: Initial dose may be increased to 100 mg/m² per day (maximum 200 mg/m² per day) 2

Monitoring Requirements

ECG Monitoring 1

• Baseline ECG before initiation
• Follow-up ECG after 3-5 days of therapy
• ECG at each dose change
• Weekly intervals initially, then every 3-6 months after stabilization
• Discontinue or reduce dose if:
  • QRS duration increases >25% from baseline
  • QRS duration exceeds 200 ms
  • PR interval increases to ≥0.3 seconds

Plasma Level Monitoring 1, 2

• Therapeutic range: 0.2-1.0 mcg/mL
• Close monitoring needed when levels exceed 0.7-1.0 mcg/mL
• Essential for patients with:
  • Severe renal impairment
  • Hepatic disease
  • Heart failure
  • Concurrent amiodarone therapy

Efficacy Data

Flecainide demonstrates significant efficacy in treating supraventricular arrhythmias:

• In PSVT: Complete suppression in 65-86% of patients 3, 4
• In PAF: 61% of patients had no recurrence at 150 mg twice daily 5
• Addition of a beta-blocker increases efficacy to >90% for AVRT 3

Safety Considerations

Common Adverse Effects 1, 6

• Dizziness
• Visual disturbances
• Headaches
• Gastrointestinal complaints

Serious Adverse Effects

• Proarrhythmic events (particularly in structural heart disease) 1, 7
• New or worsened heart failure 6
• QT prolongation and torsades de pointes 1
• Bradycardia 1

Risk Factors for Adverse Effects 1

• Female gender
• Brugada syndrome
• Coronary artery disease/previous myocardial infarction
• Renal impairment
• Elderly patients

"Pill-in-the-Pocket" Approach

For selected patients with infrequent, well-tolerated episodes of PAF, a "pill-in-the-pocket" approach may be used after safety is confirmed in a monitored setting 3.

Conclusion

Flecainide is highly effective for treating supraventricular tachyarrhythmias in patients without structural heart disease. Careful patient selection, appropriate dosing, and regular monitoring are essential to maximize benefits while minimizing risks.