Andersen - Tawil syndrome (ATS) is an autosomal - dominant or sporadic disorder characterized by ventricular
arrhythmias, periodic paralysis, and distinctive facial and skeletal dysmorphism. Mutations in KCNJ2, which encodes the
α-subunit of the potassium channel Kir2.1, were identified in patients with ATS. This genotype has been designated as
type-1 ATS (ATS1). KCNJ2 mutations are detectable in up to 60 % of patients with ATS. Cardiac manifestations of ATS
include frequent premature ventricular contractions (PVC), Q-U interval prolongation, prominent U-waves, and a special
type of polymorphic ventricular tachycardia (PMVT) called bidirectional ventricular tachycardia (BiVT). The presence of
frequent PVCs at rest are helpful in distinguishing ATS from typical catecholaminergic polymorphic ventricular tachycardia
(CPVT). In typical CPVT, rapid PMVT and BiVT usually manifest during or after exercising. Additionally, CPVT or
torsade de pointes in LQTS are faster, very symptomatic causing syncope or often deteriorate into VF resulting in sudden
cardiac death. PVCs at rest are quite frequent in ATS1 patients, however, in LQTS patients, PVCs and asymptomatic VT
are uncommon which also contributes to differentiating them.
The article describes the new electrocardiographic criteria proposed for diagnosis of type-1 Andersen-Tawil syndrome. A
differential diagnosis between Andersen-Tawil syndrome, the catecholamine polymorphic ventiruclar tachycardia and
long QT syndrome is depicted. Special attention is paid on the repolarization abnormalities, QT interval and the pathologic
U wave. In this article, we aim to provide five new electrocardiographic clues for the diagnosis of ATS1.