Life-threatening arrhythmias in children with Andersen-Tawil syndrome

Abstract

Clinical manifestation of the Andersen-Tawil syndrome (ATS) considerably vary and may include facial and skeletal dysmorphology, periodic paralysis, and ventricular arrhythmia (VA). Typical ECG features are enlarged U wave, QU prolongation, polymorphic ventricular premature beats, non-sustained polymorphic and bidirectional VT. Although the burden of VA is high, life-threatening events such as sudden cardiac death (SCD) are uncommon. This study assesses the risk of life-threatening arrhythmia requiring implantable cardioverter-defibrillator (ICD) in children with ATS. Methods: From 1998 to 2011, 8 consecutive pts from unrelated families (4 males) aged 6 to 12 with ATS were examined and followed up during 1 to 10 years. Examination includes family history, ECG, 24-hour Holter monitoring, echo, stress- and genetic testing. All patients were treated with beta-blockers. Two children with ICD were followed up during 2 and 7 years. Results: In 4 pts ATS was diagnosed due to syncope (from 2 to 12 episodes of syncope), in 3 cases it was revealed during examination before surgery for cleft palate. In all children, ATS manifests itself with facial and skeletal dysmorphic features and VA. Periodic paralysis took place in 3 pts. QU interval varies from 500 to 650 ms; QUc varies from 590 to 717 ms. All pts demonstrate polymorphic VT and 3 patients have bidirectional VT. SCD in family members at ages 10 days, 1 month, 29 years, 30 years and 36 years is observed in 3 families (with three SCD cases being observed in one family). All SCD victims had dysmorphic facial features. Recurrent syncope (despite antiarrhythmic therapy) required ICD implantation in 2 cases. Two and 12 ICD shocks terminated ventricular fibrillation (11 episodes of VF were associated with syncope) were registered in these pts during first year after ICD implantation. In all other 6 pts, beta-blocker therapy significantly depressed VA and syncope. However, it does not influence QU prolongation. Despite the fact that syncope are not registered any more, child from the family with multiple cases of SCD, who has extremely long QUc (717 ms), is scheduled for ICD implantation. Conclusions: Polymorphic VA and very high values of QUc are common for ATS children. About 1/3 of children with ATS are exposed to a high risk of VF and should be considered for ICD implantation. They experience recurrent syncope or have multiple cases of SCD in families. For asymptomatic pediatric pts with ATS, prognosis seems to be favorable, but this deserves further investigation. The use of implantable loop recorders seems appropriate.