日本小児循環器学会雑誌 Pediatric Cardiology and Cardiac Surgery

Long-QT syndrome (LQTS) is an inherited heart disease characterized by QT-interval prolongation and ventricular arrhythmias, leading to syncope and sudden cardiac death. In Japan, school-based routine electrocardiogram screenings have found a large number of asymptomatic individuals. In approximately 50% of clinically diagnosed cases, variations in >17 LQTS-causative genes have been identified. A significant contributor to the triggers of cardiac events and different aspects of gene-specific therapies is genotype. Therefore, an accurate diagnosis is crucial. Various phenotypes can be identified by T-wave morphology and the corrected QT (QTc) interval in the recovery phase of exercise stress tests. Genetic testing should be performed in patients with a clear phenotype, and it is important to confirm that the genotype is compatible with the phenotype. The main factors found to be associated with cardiac-event risk were sex, QTc, variant type/location, and history of cardiac events. There was also a significant effect of age on the QTc interval and cardiac-event risk during childhood and adolescence.