What is the recommended treatment and dosage for Propafenona (propafenone) in patients with irregular heartbeat, such as atrial fibrillation and ventricular arrhythmias?

Propafenone Treatment for Irregular Heartbeat

Propafenone is effective for maintaining sinus rhythm in patients with atrial fibrillation, with a recommended starting dose of 225 mg twice daily, which can be titrated up to 425 mg twice daily based on response and tolerance. 1

Dosage Recommendations

• For oral extended-release propafenone (ER capsules):

  • Initial dose: 225 mg every 12 hours 1
  • Dose may be increased at minimum 5-day intervals to 325 mg every 12 hours 1
  • If additional therapeutic effect is needed, dose may be further increased to 425 mg every 12 hours 1
  • Dose should be reduced in patients with hepatic impairment or significant QRS widening 1

• For immediate-release propafenone (tablets):

  • For maintenance therapy in atrial fibrillation: 150-300 mg three times daily 2, 3
  • For acute conversion of recent-onset atrial fibrillation: 450-600 mg as a single oral loading dose 4

Efficacy

• Propafenone significantly prolongs the time to first recurrence of symptomatic atrial fibrillation compared to placebo 1
• Dose-dependent response has been observed, with higher doses (325 mg BID and 425 mg BID) showing greater efficacy than lower doses (225 mg BID) 1
• In controlled trials, propafenone 300 mg twice daily demonstrated a 6-fold reduction in risk of treatment failure compared to placebo for both paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation 5
• Propafenone maintains sinus rhythm in approximately 67% of patients at 6 months after cardioversion compared to 35% with placebo 3

Contraindications and Precautions

• Propafenone should not be used in patients with: 2, 6

  • Ischemic heart disease or coronary artery disease
  • Left ventricular dysfunction or heart failure
  • Significant structural heart disease
  • Brugada syndrome
  • Severe obstructive lung disease
  • Significant sinus or AV conduction disease
  • Cardiogenic shock or hypotension

• Serious cardiovascular side effects may occur, including: 6

  • Ventricular tachycardia and ventricular fibrillation (1-5% incidence)
  • QRS prolongation (increase >25% from baseline indicates proarrhythmic risk)
  • Rapid atrial flutter with 1:1 AV conduction

Monitoring Recommendations

• Regular ECG monitoring is essential during initiation and dose adjustments 6
• QRS duration should be monitored; an increase >25% from baseline indicates potential proarrhythmic risk 2, 6
• Concomitant AV nodal blocking agent (beta-blocker or non-dihydropyridine calcium channel antagonist) should be administered at least 30 minutes before propafenone to prevent rapid conduction of atrial flutter 2

Special Considerations

• Propafenone exhibits dose-dependent pharmacokinetics with wide variation in plasma concentrations between individuals 7
• The drug has weak beta-blocking activity in addition to its sodium channel blocking effects 2, 7
• Propafenone may interact with digoxin, increasing serum digoxin levels 2
• For "pill-in-the-pocket" approach (patient self-administration during episodes), propafenone should only be used after being observed to be safe in a monitored setting 2

Comparative Efficacy

• In the Canadian Trial of Atrial Fibrillation (CTAF), propafenone was less effective than amiodarone but had fewer side effects 2
• Propafenone and sotalol appear equally effective in maintaining sinus rhythm (30% vs. 37% of patients in sinus rhythm at 12 months) 2
• Propafenone was more effective than quinidine in randomized comparisons 2

By following these dosage recommendations and monitoring guidelines, propafenone can be an effective treatment for atrial fibrillation and ventricular arrhythmias in appropriately selected patients without structural heart disease or coronary artery disease.