Propafenone (Rythmol) Treatment Protocol for Irregular Heartbeat
Propafenone is indicated for paroxysmal atrial fibrillation/flutter and paroxysmal supraventricular tachycardia associated with disabling symptoms in patients without structural heart disease, with dosing typically ranging from 450-900 mg daily in divided doses. 1
Indications and Patient Selection
Propafenone is specifically indicated for:
- Paroxysmal atrial fibrillation/flutter with disabling symptoms
- Paroxysmal supraventricular tachycardia with disabling symptoms
- Documented life-threatening ventricular arrhythmias 1
Critical Contraindications
- Structural heart disease, especially ischemic heart disease
- Left ventricular dysfunction or heart failure
- Obstructive lung disease
- Wolff-Parkinson-White syndrome with pre-excited atrial fibrillation 2
Dosing Protocol
For Maintenance Therapy
- Standard daily dose: 450-900 mg divided into 2-3 doses 3
- Typical starting dose: 150 mg three times daily 4
- Sustained-release formulation: 225-425 mg twice daily 3
For Acute Conversion of Recent-Onset AF
- Oral loading dose: 450-600 mg as a single dose
- Conversion typically occurs within 3-4 hours
- Success rate: 72-78% within 8 hours 5
Monitoring Requirements
Before Initiation:
- Echocardiography to rule out structural heart disease
- Baseline ECG to assess PR interval and QRS duration
- Serum electrolytes and renal function 2
During Treatment:
- ECG monitoring for QRS widening (propafenone causes dose-related increases in PR interval and QRS duration)
- Monitor for signs of heart failure or ischemia
- Regular assessment of electrolytes and renal function 1
Efficacy and Comparative Effectiveness
- In the UK PSVT study, propafenone 300 mg twice daily was effective, with 300 mg three times daily showing greater efficacy but more side effects 3
- In placebo-controlled studies, propafenone reduced days in AF from 51% to 27% 3
- In maintenance therapy after cardioversion, 67% of patients remained free from recurrent symptomatic arrhythmia at 6 months compared to 35% with placebo 4
- Propafenone and sotalol showed similar efficacy in maintaining sinus rhythm (30% vs. 37% of patients in sinus rhythm at 12 months) 3
- Amiodarone is more effective than propafenone for maintaining sinus rhythm, as demonstrated in the CTAF study 3
Adverse Effects and Safety Considerations
Major Risks
- Proarrhythmic effects, particularly in patients with structural heart disease
- Negative inotropic effect that may precipitate heart failure
- Conduction abnormalities (PR prolongation, QRS widening)
- Conversion of AF to atrial flutter (3.5-5% of patients) 5
Common Side Effects
- Neurological: dizziness, blurred vision
- Gastrointestinal: nausea, vomiting, constipation
- Cardiac: bradycardia, AV block 6, 7
Special Considerations
Pharmacokinetic Variability:
- Propafenone exhibits extensive first-pass metabolism with nonlinear pharmacokinetics
- Wide interindividual variability in plasma concentrations
- Genetic polymorphism affects metabolism (extensive vs. poor metabolizers) 1
Drug Interactions:
- Beta-blockers: enhanced negative inotropic and chronotropic effects
- Digoxin: increased digoxin levels
- Warfarin: increased anticoagulant effect 1
Atrial Flutter Risk:
- Monitor for conversion of AF to atrial flutter with 1:1 conduction
- Consider concomitant AV nodal blocking agents 1
Clinical Pearls
- Propafenone has beta-blocking activity approximately 1/40th that of propranolol, which contributes to its antiarrhythmic effect but also to potential adverse effects 1
- The drug reaches peak plasma concentrations within 2-4 hours of oral administration 5
- Therapeutic plasma concentrations range from 0.2-1.5 μg/mL for suppression of ventricular ectopic activity 1
- Propafenone should be initiated in a hospital setting when used for life-threatening ventricular arrhythmias 1
Remember that propafenone has not been shown to enhance survival in patients with ventricular or atrial arrhythmias, and treatment decisions should always prioritize morbidity, mortality, and quality of life outcomes.