Korean Circ J.  2022 Oct;52(10):771-781. 10.4070/kcj.2022.0081.

The Outcome of Long QT Syndrome, a Korean Single Center Study

  • 1Department of Pediatrics, Seoul National University Children’s Hospital, Seoul National University College of Medicine, Seoul, Korea
  • 2Department of Pediatrics, Gachon University Gil Medical Center, Incheon, Korea
  • 3Department of Pediatrics, Sejong General Hospital, Bucheon, Korea
  • 4Department of Internal Medicine, Seoul National University Children’s Hospital, Seoul National University College of Medicine, Seoul, Korea


Background and Objectives
Although long QT syndrome (LQTS) is a potentially lifethreatening inherited cardiac channelopathy, studies documenting the long-term clinical data of Korean patients with LQTS are scarce.
This retrospective cohort study included 105 patients with LQTS (48 women; 45.7%) from a single tertiary center. The clinical outcomes were analyzed for the rate of freedom from breakthrough cardiac events (BCEs), additional treatment needed, and death.
LQTS was diagnosed at a median age of 11 (range, 0.003–80) years. Genetic testing was performed on 90 patients (yield, 71.1%). The proportions of genetically confirmed patients with LQTS types 1, 2, 3, and others were 34.4%, 12.2%, 12.2%, and 12.2%, respectively. In the symptomatic group (n=70), aborted cardiac arrest was observed in 30% of the patients. Treatments included medications in 60 patients (85.7%), implantable cardioverter-defibrillators in 27 (38.6%; median age, 17 years; range, 2–79 years), and left cardiac sympathetic denervation surgery in 7 (10%; median age, 13 years; range, 2–34). The 10-year BCE-free survival rate was 73.2%. By genotype, significant differences were observed in BCEs despite medication (p<0.001). The 10-year BCE-free survival rate was the highest in patients with LQTS type 1 (81.8%) and the lowest in those with multiple LQTS-associated mutations (LQTM). All patients with LQTS survived, except for one patient who had LQTM.
Good long-term outcomes can be achieved by using recently developed genetically tailored management strategies for patients with LQTS.


Long QT syndrome; Channelopathies; Genetics; Sudden cardiac death; Sympathectomy


  • Figure 1 The mode of initial presentation in the symptomatic group.

  • Figure 2 The distributions of genetic mutations are confirmed in the genetically verified group.G−/P+ = genotype negative and phenotype positive; JLNS = Jervell Lange-Nielsen syndrome; LQT1 = congenital long QT syndrome type 1; LQT2 = congenital long QT syndrome type 2; LQT3 = congenital long QT syndrome type 3; LQT4 = congenital long QT syndrome type 4; LQT7 = congenital long QT syndrome type 7; LQT8 = congenital long QT syndrome type 8; LQTM = multiple long QT syndrome-associated mutations; VUS = variant of uncertain significance.

  • Figure 3 BCE-free survival curve for entire genetically verified LQTS. (A) BCE-free survival through each genotype, statistical significance was analyzed except for LQT4, 7, 8 which were rare. (B) When comparing LQT1, 2, and 3, which account for most of LQTS, the prognosis was poor in the order of LQT3, LQT2, and LQT1.BCE = breakthrough cardiac event; G−/P+ = genotype negative and phenotype positive; LQTS = long QT syndrome; LQT1 = congenital long QT syndrome type 1; LQT2 = congenital long QT syndrome type 2; LQT3 = congenital long QT syndrome type 3; LQT4 = congenital long QT syndrome type 4; LQT7 = congenital long QT syndrome type 7; LQT8 = congenital long QT syndrome type 8; LQTM = multiple LQTS-associated mutations; VUS = variant of uncertain significance.

  • Figure 4 Individual/cumulative risk factors for appropriate ICD shock. Among the ICD recipients, the Kaplan-Meier curves were analyzed through the risk factors, primary vs. secondary prevention (A), QTc ≥500 ms (B), and family history of sudden cardiac death (C) for the event that received appropriate shock treatment.ICD = implantable cardioverter-defibrillator; QTc = corrected QT interval.


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