Flecainide as first-line treatment for supraventricular tachycardia in newborns

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

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.

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