The impact of age on long QT syndrome

arrhythmogenic disorder predisposing to sudden cardiac death (SCD) secondary to polymorphic VT; mostly torsades de pointes. The mean age at presentation is 14 years of age, whilst the median age of individuals who die of LQTS is 32 years, with men predominantly affected. Inherited LQTS is characterized by prolonged ventricular repolarization represented on the ECG by an increased corrected QT (QTc) interval. Three main genes account for approximately 90% of all genotyped cases of LQTS. The risk of arrhythmic events is determined by age, sex, QTc interval, a history of syncope, and genotype, and in acquired LQTS QTc prolongation secondary to certain medication further increases the risk of cardiac arrhythmias (http://crediblemeds.org). Children and adolescents constitute an important risk group for inherited LQTS. During childhood, the risk of cardiac events is significantly higher in LQT1 males than in LQT1 females (hazard ratio [HR] = 1.72), whereas there is no significant gender-related difference among LQT2 and LQT3 carriers [1]. During adulthood, LQT1 females (HR = 3.35) and LQT2 females (HR = 3.71) have a significantly higher risk of cardiac events than age-matched males. The lethality of cardiac events is highest in LQT3 males and females (19% and 18%), and higher in LQT1 and LQT2 males (5% and 6%) than in LQT1 and LQT2 females (2% for both). The analysis of serial QTc interval measurements in a large cohort of children and adolescents with LQT1 and LQT2 demonstrated two main findings. Firstly, both LQT1 and LQT2 male patients show significant QTc interval shortening after the onset of puberty; in LQT2 male patients, this is preceded by a progressive QTc interval prolongation. Secondly, the age of 12 to 14 years is an important transitional period in which differences between males and females for both genotypes are seen, ages broadly corresponding with the onset of puberty [2]. The authors concluded that for risk stratification and management, clinicians should be aware of these significant age-, sex-, and genotyperelated trends in QTc interval, especially the important role of the onset of puberty. LQT2 patients seem to be more sensitive to variations of sex hormone concentrations than LQT1 patients. A recent analysis of the QTc interval in healthy individuals during childhood and adolescence [3] observEditorial