What is the recommended treatment and dosage for Flecanide (Flecainide) in patients with arrhythmias, such as paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation (PAF)?

Flecainide for Arrhythmias: Dosage and Treatment Recommendations

Flecainide is recommended for paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation (PAF) at an initial dose of 50 mg twice daily, which can be increased in increments of 50 mg twice daily every four days to a maximum of 300 mg/day, but only in patients without structural heart disease.

Indications and Contraindications

Flecainide is indicated for:

• Prevention of PSVT, including atrioventricular nodal reentrant tachycardia and atrioventricular reentrant tachycardia 1
• Prevention of PAF associated with disabling symptoms 1
• Prevention of documented life-threatening ventricular tachycardia 1

Absolute contraindications:

• Structural heart disease
• Recent myocardial infarction
• Left ventricular dysfunction
• Hemodynamic instability 2
• Severe renal impairment (requires dose adjustment) 3

Dosing Protocol

For PSVT and PAF:

1. Initial dose: 50 mg every 12 hours 1
2. Titration: Increase in increments of 50 mg twice daily every four days until efficacy is achieved 1
3. Maximum dose: 300 mg/day (150 mg twice daily) 1
4. Maintenance: Once adequate control is achieved, dose may be reduced to minimize side effects 1

Special Considerations:

• Steady-state plasma levels may not be achieved until 3-5 days of therapy 1
• Patients with severe renal impairment require dose adjustment 1, 3
• Occasional patients may benefit from dosing at 8-hour intervals rather than 12-hour intervals 1

Efficacy

Flecainide has demonstrated superior efficacy compared to placebo in multiple studies:

• In PSVT, flecainide completely suppressed episodes in 65% of patients 4
• Addition of a beta-blocker increases efficacy to >90% of patients achieving abolition of symptomatic tachycardia 4
• In one randomized trial, only 8 of 34 patients had recurrence during flecainide therapy, compared with 29 of 34 patients on placebo 4
• For AVRT, oral administration of flecainide (200-300 mg/day) prevented induction of sustained tachycardia in 17 of 20 patients 4

Monitoring and Follow-up

• ECG monitoring is recommended during initiation of therapy, especially in patients with history of cardiac disease 1
• QRS widening should not exceed 150% of pretreatment QRS duration 4
• Exercise testing may help detect QRS widening that occurs only at rapid heart rates 4
• Plasma trough levels should be monitored, particularly in patients with renal impairment 1

Safety Profile

Common side effects:

• Central nervous system: Dizziness, visual disturbances, headache 5, 6
• Cardiac: Potential for proarrhythmic effects, especially in patients with structural heart disease 5

Safety data:

• In a multicenter trial of 151 patients, 87% of PSVT and 73% of PAF patients had symptomatic improvement 5
• Cardiac adverse events occurred in 11 patients, including proarrhythmic events (3 patients) and new/worsened heart failure (7 patients) 5
• Side effects are most common in patients with chronic atrial fibrillation and structural heart disease 5

Alternative Treatment Options

When flecainide is contraindicated or ineffective:

1. Propafenone: Similar efficacy profile to flecainide 7
2. Sotalol: In one study, 13 of 16 patients were free of symptomatic recurrences during a median follow-up of 36 months 4
3. Beta-blockers or calcium channel blockers: First-line for long-term management in many patients 2
4. Catheter ablation: Definitive treatment with high success rates, especially for AVNRT and AVRT 2

Single-Dose "Pill-in-the-Pocket" Approach

For selected patients with infrequent but prolonged episodes:

• A single oral dose of flecainide (approximately 3 mg/kg) can be effective for terminating acute episodes 4
• In one study of children and young adults, a single dose (2.9 ± 0.3 mg/kg) terminated PSVT in 22 of 25 patients 8
• This approach should be reserved for patients without structural heart disease who have infrequent, well-tolerated episodes 4

Practical Considerations

• Flecainide should be initiated in-hospital with rhythm monitoring for patients with sustained ventricular tachycardia 1
• For patients with PSVT or PAF, outpatient initiation may be appropriate in selected cases without structural heart disease 1
• Combining flecainide with a beta-blocker is often recommended to enhance efficacy and reduce risk of 1:1 conduction if atrial flutter occurs 4

Remember that catheter ablation is the definitive treatment for many forms of PSVT and should be considered for patients with frequent symptomatic episodes.