What is the recommended use and dosage of Flecainide (antiarrhythmic medication) for treating arrhythmias?

Flecainide for Treating Arrhythmias: Recommended Use and Dosage

Flecainide is recommended for ongoing management in patients without structural heart disease or ischemic heart disease who have supraventricular tachyarrhythmias (particularly AVNRT and AVRT) and are not candidates for, or prefer not to undergo, catheter ablation, and in whom beta blockers, diltiazem, or verapamil are ineffective or contraindicated. 1

Indications and Efficacy

• Flecainide is indicated primarily for supraventricular tachyarrhythmias including atrial fibrillation, AVNRT (AV nodal reentrant tachycardia), and AVRT (AV reentrant tachycardia) in patients without structural heart disease 1
• In randomized controlled trials, flecainide has shown a 93% probability of effective treatment (defined as <2 attacks of arrhythmia over 12 months) for supraventricular tachycardias 1
• Flecainide has demonstrated superior efficacy compared to verapamil for long-term management, with 30% of patients experiencing complete suppression of all symptomatic episodes on flecainide versus only 13% on verapamil 1
• At doses between 200 and 300 mg/day, flecainide completely suppressed episodes in 65% of patients with paroxysmal atrial fibrillation 2

Dosing Recommendations

For Adults:

• Initial dose: 100 mg twice daily 3, 4
• Titration: May increase by 50 mg twice daily every 4 days as needed 4
• Maximum dose: 200 mg twice daily 3, 4
• For "pill-in-the-pocket" approach (single-dose therapy for acute conversion of recent-onset atrial fibrillation): 200-300 mg as a single oral dose, after safety has been established in the hospital setting 1

For Children:

• Under six months: Initial dose of approximately 50 mg/m² body surface area daily, divided into 2-3 equally spaced doses 3
• Over six months: Initial dose may be increased to 100 mg/m² per day 3
• Maximum dose: 200 mg/m² per day 3
• Pediatric use should be directly supervised by a cardiologist skilled in treating arrhythmias in children 3

For Patients with Renal Impairment:

• Severe renal impairment (creatinine clearance ≤35 mL/min/1.73 m²): Initial dose of 100 mg once daily (or 50 mg twice daily) 3
• Less severe renal disease: Initial dose of 100 mg every 12 hours 3
• Frequent plasma level monitoring is required in these patients to guide dosage adjustments 3

Contraindications and Precautions

• Absolute contraindications: Structural heart disease, coronary artery disease, or reduced left ventricular ejection fraction 1, 5
• Flecainide has been associated with increased mortality in patients with prior myocardial infarction and should be avoided in this population 5, 6
• Concomitant use with amiodarone requires reducing the usual flecainide dose by 50% and close monitoring 3
• ECG monitoring is essential, with dose reduction or discontinuation if QRS widens by >25% from baseline 5
• Therapeutic plasma levels range from 0.2-1.0 mcg/mL; levels >1.0 mcg/mL increase risk of adverse cardiac events 3

Monitoring Requirements

• Baseline ECG prior to initiating treatment 5
• Regular ECG monitoring during therapy, particularly when initiating treatment or adjusting dosage 5
• Plasma level monitoring is strongly recommended in patients with:
  • Severe renal failure 3
  • Severe hepatic disease 3
  • Concurrent amiodarone therapy 3
  • Congestive heart failure 3
  • Moderate renal disease 3
• For children: Obtain plasma trough flecainide levels and ECGs at steady state (after at least 5 doses) after initiation or dose changes 3

Adverse Effects

• Cardiac: Proarrhythmia, conduction abnormalities, negative inotropic effects, new or worsened heart failure 4, 6
• Non-cardiac: Dizziness (most common), blurred vision, difficulty focusing 6
• Discontinuation rates due to adverse effects range from 5-20% in clinical trials 1, 7

Special Considerations

• When used for paroxysmal atrial fibrillation, the "pill-in-the-pocket" approach requires careful patient selection and initial in-hospital evaluation 1, 5
• Flecainide is often combined with beta-blocking agents to enhance efficacy and reduce the risk of one-to-one conduction over the AV node if atrial flutter occurs 1
• When transferring patients from another antiarrhythmic drug to flecainide, allow at least 2-4 plasma half-lives to elapse for the drug being discontinued before starting flecainide at the usual dosage 3

Flecainide remains an important option in the management of supraventricular arrhythmias when used appropriately in carefully selected patients without structural heart disease 6, 8.