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Usefulness of propafenone for supraventricular arrhythmias in infants and children
1Department of Pediatric Cardiology, Children's Hospital, Hannover, Germany.
Insights
Propafenone effectively treats supraventricular arrhythmias in children, with ECG changes guiding dosage more than serum levels. Monitor liver enzymes, especially with higher doses.
Area of Science:
- Pediatric Cardiology
- Clinical Pharmacology
Background:
- Supraventricular arrhythmias are common in children.
- Propafenone is an antiarrhythmic medication used in pediatric populations.
- Understanding dose-response relationships and safety profiles is crucial for effective pediatric treatment.
Purpose of the Study:
- To investigate the relationship between propafenone dosage, serum levels, electrocardiographic (ECG) parameters, efficacy, and adverse effects in children.
- To determine optimal strategies for propafenone dosing in pediatric patients with symptomatic supraventricular arrhythmias.
Main Methods:
- A cohort of 47 children with symptomatic supraventricular arrhythmias received oral propafenone.
- Propafenone dosage, serum trough levels (gas chromatography), ECG parameters (PR interval, QRS duration), and adverse events were monitored.
- Follow-up averaged 14.3 months.
Main Results:
- Propafenone was effective in 87.2% of patients (41/47).
- Increased PR interval and QRS duration correlated more strongly with dose increments than serum levels.
- Some patients showed significant QRS prolongation at low doses; 6.1% were suspected poor metabolizers.
- Mild liver enzyme elevation occurred in 5 patients on higher doses; no proarrhythmia was observed on Holter monitoring.
Conclusions:
- Serial ECG monitoring (PR interval, QRS duration) is more valuable than serum propafenone levels for adjusting dosage in children.
- Close monitoring of serum liver enzymes is recommended with higher propafenone doses.
- While generally safe, potential for QRS prolongation and rare adverse events necessitates careful patient management.
Abstract:
The relation between propafenone dose, serum level, electrocardiographic parameters, antiarrhythmic drug efficacy and adverse effects was studied in 47 children with symptomatic supraventricular arrhythmias aged 1 day to 10.3 years (median 2.2 months) with a mean follow-up of 14.3 months. Propafenone trough serum levels were measured using gas chromatography. Oral propafenone (mean dose 353 mg/m2/day) was effective in 41 of the 47 patients (87.2%). Serum levels did not differ between patients responding and not responding to propafenone (0.45 +/- 0.40 vs 0.36 +/- 0.41 mg/liter). PR interval and QRS complex duration increased more significantly with propafenone dose increments (p < 0.001), than with propafenone serum levels (p < 0.05). At successful treatment PR interval and QRS complex were prolonged by a mean of 19.2 and 20.5% compared with pretreatment status. Five patients exhibited unexpected marked QRS complex prolongation (50 to 200%) despite low propafenone dosage (< 300 mg/m2/day) and level ranging from 0.05 to 1.33 mg/liter. Three patients (6.1%) were suspected of being "poor" metabolizers of propafenone. Mild chronic elevation of serum liver enzymes was observed in 5 patients treated with a larger dose (mean 448 mg/m2/day, p < 0.001). No proarrhythmia was noted on serial Holter monitors. One patient with Wolff-Parkinson-White syndrome and a normal heart had cardiac arrest after aspiration. Serial monitoring of PR interval and QRS complex duration was more useful for proper dosage adjustment than propafenone serum levels. Serum liver enzymes should be closely monitored when using higher propafenone doses. Malignant proarrhythmia could not be excluded in the 1 patient with cardiac arrest.