Flecainide as first-line treatment for supraventricular tachycardia in newborns.

Background: Flecainide for the treatment of supraventricular tachycardia (SVT) in newborns is still controversial because of its potentially severe proarrhythmic effects.

Methods And Results: Between January 2004 and December 2006, we used flecainide to treat 20 consecutive newborns (15 males) with paroxysmal SVT without any structural heart disease. Their age at hospitalization was 11.5 +/- 11.1 days. The intravenous administration of flecainide (1 mg/kg) effectively restored sinus rhythm in all the patients. Once stable sinus rhythm had been restored, the drug was administered orally at a dose of 2 mg/kg/day twice daily, which was uptitrated as the patients gained weight. The patients were followed up for up to 24 months with clinical evaluations, baseline ECG and 24-h Holter monitoring every 3 months. There were neither deaths nor any episodes of heart failure or sustained ventricular tachycardia during follow-up. SVT were completely controlled in 17 patients (85%), with an oral dose of 3.35 +/- 1.35 mg/kg/day of flecainide; in the remaining three patients with refractory arrhythmias, propranolol was added for optimal treatment. No significant increase in the duration of QRS (70 +/- 1.09 vs. 63.8 +/- 1.87 ms, P = NS) or any significant QTc prolongation (413 +/- 7.4 vs. 412.6 +/- 8.01 ms, P = NS) was observed. One patient developed an incomplete right bundle branch block promptly reverted by reducing the dose.

Conclusion: This preliminary experience indicates that flecainide is well tolerated and effective as first-line treatment for paroxysmal SVT in newborns without structural heart disease.