Korean Circ J.  2002 Sep;32(9):798-806. 10.4070/kcj.2002.32.9.798.

Clinical and Electrocardiographic Features of Patients with Congenital Long QT Syndrome

• Kim JH
• Nam GB
• Kim HK
• Rhee KS
• Han KH
• Choi KJ
• Ko JK
• Park IS
• Kim YH

• KMID: 2227258
• DOI: http://doi.org/10.4070/kcj.2002.32.9.798

Abstract

BACKGROUND AND OBJECTIVES: Congenital long QT syndrome (LQTS) is characterized by the prolongation of the QT interval, frequent episodes of syncope and Torsades de Pointes (TdP). The clinical features and electrocardiographic findings in Korean patients with LQTS have not been reported.
SUBJECTS AND METHODS
We retrospectively analyzed the clinical characteristics, ECG features and response to treatments in 11 patients (6 men, 5 women) with congenital LQTS.
RESULTS
The mean age at the time of the first episode was 19.4+/-22.6 years old (range: 170 years). Clinical presentations were syncope, seizure or sudden cardiac death (SCD). Predisposing factors included exercise, sudden startle or sleep. Only three patients showed familial histories of syncope or SCD. The average QTc interval was 0.58+/-0.05 second (range: 0.47-0.61 seconds). T wave morphologies were classified as normal-appearing, broad-based, low amplitude/bifid or late onset. For its management, bblockers were used in 7 patients. In 2 patients, whose clinical events were related with to an increased vagal tone or were aggravated by bblocker therapy, mexiletine was prescribed. When bradycardia or AV block was documented, pacemakers were implanted. For 2 patients at high risk of sudden cardiac death, cardioverter-defibrillators were implanted. During a mean follow up period of 23.5+/-20.2 months (range: 364 months), symptoms (cardiac arrest) recurred in 1 patient.
CONCLUSION
Congenital LQTS is a heterogeneous disease, showing diverse clinical manifestations, ECG features, and response to pharmacological management. Further research on the genotype-phenotype relationship will refine the management, enabling gene-specific treatment of this life-threatening disease.

Keyword

Long QT syndrome; Electrocardiography; Death, sudden; Syncope; Arrhythmia

MeSH Terms

Arrhythmias, Cardiac
Atrioventricular Block
Bradycardia
Causality
Death, Sudden
Death, Sudden, Cardiac
Electrocardiography*
Follow-Up Studies
Humans
Long QT Syndrome*
Male
Mexiletine
Retrospective Studies
Seizures
Syncope
Torsades de Pointes
Mexiletine