All 20 patients with LQTS were mostly symptomatic at presentation. Owing to the geographical region and ethnicity of the Thai population, we conclude that the ratio of patients who develop cardiac symptoms at rest or during sleep might be higher than in other Asian countries.

BackgroundCongenital long QT syndrome (LQTS) is an inheritable arrhythmic disorder which is linked to at least 17 genes. The clinical characteristics and genetic mutations may be variable among different population groups and they have not yet been studied in Thai population.MethodsClinical characteristics were retrospectively reviewed from children and young adults with congenital long QT syndrome whose blood samples were sent for genotyping during 1998–2017. Sangers sequencing was used to sequentially identify KCNQ1 or KCNH2 genetic variants. Whole exome sequencing (WES) was used to identify variants in all other known LQTS genes.ResultsOf the 20 subjects (17 families), 45% were male, mean QTc was 550.3 ± 68.8 msec (range 470–731 msec) and total Schwartz's score was 5.6 ± 1.2 points (range 3–8 points). Fifty percent of patients had events at rest, 30% had symptoms after adrenergic mediated events, and 20% were asymptomatic. We discovered pathogenic and likely pathogenic genetic variants in KCNQ1, KCNH2, and SCN5A in 6 (35%), 4 (24%), and 2 (12%) families, respectively. One additional patient had variance of unknown significance (VUS) in KCNH2 and another one in ANK2. No pathogenic genetic variant was found in 3 patients (18%). Most patients received beta-blocker and 9 (45%) had ICD implanted. LQT1 patients were either asymptomatic or had stress-induced arrhythmia. Most of the LQT2 and LQT3 patients developed symptoms at rest or during sleep.ConclusionsOur patients with LQTS were mostly symptomatic at presentation. The genetic mutations were predominantly in LQT1, LQT2, and LQT3 genes.

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In the last issue, two case reports separately present examples of the extremely rare and complex congenital heart diseases that show concordant atrioventricular connections to the L-looped ventricles in the presence of situs solitus. Both cases highlight that the relationship between the two ventricles within the ventricular mass is not always harmonious with the given atrioventricular connection. Such disharmony between the connections and relationships requires careful assessment of the three basic facets of cardiac building blocks, namely their morphology, the relationship of their component parts, and their connections with the adjacent segments. 3D imaging and printing can now facilitate an otherwise difficult diagnosis in such complex situations. Rotation of either the 3D images or the models permit accurate assessment of the ventricular topologic pattern by creating the right ventricular en-face septal view, thus facilitating placement of the observer's hands. As we now emphasize, an alternative approach, which might prove more attractive to imagers, is to rotate the ventricular mass to provide the ventricular apical view, thus permitting determination of the ventricular relationship without using the hands.