Flecainide improves cardiac synchronization in an early infant with Wolff-Parkinson-White syndrome with left ventricular dyssynchrony

Abstract

Recently, cases of pharmacological resynchronization for Wolff-Parkinson-White syndrome (WPWS) in children with left ventricular dyssynchrony (LVD) were reported, but an appropriate pharmacological therapy has not yet been established. A 3-month-old, previously healthy female patient was referred to our hospital due to supraventricular tachycardia (SVT). After resolution of the SVT, 12-lead electrocardiography (ECG) showed ventricular pre-excitation. Transthoracic echocardiography showed LVD with no findings of congenital heart disease or cardiomyopathy. To prevent SVT recurrence, oral propranolol administration was started, but the SVT recurred one month later. To prevent further recurrences, oral flecainide administration was started, as the patient's body weight was insufficient for catheter ablation to be performed safely. When the flecainide dosage was increased to 50 mg/m²/day, the pre-excitation resolved, and the LVD improved. Holter ECG showed that the resolution of pre-excitation depended on the serum concentration of flecainide. There are only few reports on pharmacological resynchronization in WPWS patients with LVD (LVD-WPWS). The present report is the first to examine the efficacy of flecainide in patients with recurrent SVT. Flecainide may be a safe and effective alternative resynchronization therapy for LVD-WPWS patients, especially for children in whom catheter ablation cannot be performed safely due to insufficient body weight. <Learning objective: While cases of pharmacological resynchronization for Wolff-Parkinson-White syndrome (WPWS) in children with left ventricular dyssynchrony (LVD) have been reported, an appropriate pharmacological therapy has yet to be established. Flecainide may be a safe and effective alternative resynchronization therapy for WPWS with LVD, especially for children in whom catheter ablation cannot be performed safely due to insufficient body weight.>.

Keywords: Dyssynchrony; Flecainide; Infant; Resynchronization; Wolff–Parkinson–White syndrome.

Fig. 1

Composite figure of serial electrocardiograms (ECG). (A) ECG at the first episode of tachyarrhythmia showing regular short RP tachycardia with a QRS rate of 272 bpm and left bundle branch block. (B) ECG at sinus rhythm after termination of tachyarrhythmia showing delta waves positive in leads I, II, aVF, V4, V5, and V6, and negative in lead III, with an rS pattern in V1, suggesting pre-excitation via the right anteroseptal accessory pathway. (C) ECG at administration of adenosine triphosphate for supraventricular tachycardia, with a sweep speed of 50 mm/s, showing two cycles of narrow QRS tachycardia just before conversion to sinus rhythm, suggesting that the tachycardia was orthodromic atrioventricular reciprocating tachycardia with aberrant conduction of left bundle branch. (D) ECG after administration of flecainide showing disappearance of delta waves with normal QRS morphology.

Fig. 2

Echocardiography at sinus rhythm after termination of tachyarrhythmia. (A) M-mode echocardiography showing early contraction of intraventricular septum (IVS) (red arrow) in the diastolic phase and paradoxical motion of IVS in the systolic phase (yellow arrow), with a left ventricular end-diastolic diameter of 25.7 mm (Z score 0.4) and left ventricular ejection fraction of 48.5% (Biplane Modified Simpson method). (B) Circumference strain by speckle tracking echocardiography showing early contraction of the anteroseptal wall (red arrow) and late contraction of the left ventricular posterior wall (blue arrow), with a septal-to-posterior-wall motion delay of 268 ms.

Fig. 3

Echocardiography after the disappearance of delta waves. (A) M-mode echocardiogram showing improvement in both synchronization and contraction of the left ventricular wall, with an left ventricular ejection fraction of 70.0%. (B) Circumference strain by speckle tracking echocardiography after the disappearance of delta waves showing an improvement in septal-to-posterior-wall motion delay (54 ms).