Long QT syndrome: a Korean single center study

Area of Science:

• Cardiology
• Genetics
• Molecular Biology

Background:

• Long QT syndrome (LQTS) is a rare hereditary disorder associated with ventricular tachyarrhythmia and sudden cardiac death.
• Genetic mutations in ion channel genes are implicated in LQTS pathogenesis.
• Understanding genotype-phenotype correlations and penetrance is crucial for risk stratification.

Purpose of the Study:

• To investigate the genetic basis and clinical presentation of LQTS in a Korean cohort.
• To identify specific genetic mutations and assess their penetrance.
• To determine the correlation between QTc interval and major cardiac events.

Main Methods:

• Prospective investigation of 62 LQTS patients and 19 family members.
• Genetic analysis for LQT gene mutations.
• Clinical data collection including ECG, cardiac events, and treatment response.
• Statistical analysis to correlate QTc with clinical parameters and identify predictive cut-off values.

Main Results:

• Genetic mutations were identified in 40 out of 61 LQTS patients, with KCNQ1 and KCNH2 being the most frequent.
• The penetrance of LQT gene mutations in family members was 57.9%.
• Longer QTc intervals were significantly associated with a history of syncope, ventricular tachycardia, and aborted cardiac arrest. A QTc > 0.508 sec predicted major cardiac events with 80.6% sensitivity.
• Beta-blocker therapy showed significant QTc reduction (P = 0.007).

Conclusions:

• Congenital LQTS is a potentially lethal disease with diverse genetic mutations and low penetrance in the studied Korean population.
• Specific QTc cut-off values can aid in identifying patients at high risk for major cardiac events.
• Genetic testing and risk stratification are essential for managing LQTS patients.