Key result
An 8-year-old boy with long QT syndrome and nocturnal cardiac events caused by a KCNH2 missense mutation (G604S) had no recurrence of syncope or cardiac events over 10 months of pharmacological treatment.
Case Report (n=1)
No
Highlights the importance of genetic testing in Long QT Syndrome due to potential genotype-phenotype mismatches, which can impact therapeutic options and risk stratification.
Successful short-term control in this KCNH2 variant; leaves open generalizability and requires prospective validation.
An 8-year-old boy suffered from an unconsciousness attack and torsade de pointes arrhythmia during sleep or at rest. His electrocardiogram showed prolonged QT intervals, but the T wave morphology was atypical for type 1, 2 or 3 congenital long-QT syndrome (LQTS). Intravenous epinephrine slightly prolonged the QT interval whereas mexiletine infusion shortened the QT interval. Although these clinical characteristics might suggest type 3 LQTS, a genetic analysis identified the G604S-KCNH2 mutation (type 2 LQTS). Because mismatches between the genotype and phenotype of LQTS are possible, genetic analysis of LQTS is important to identify the most appropriate therapeutic option and risk stratification.
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Sato et al. (2012) conducted a case report in Long QT Syndrome (LQTS) (n=1). Propranolol, mexiletine, and potassium L-aspartate was evaluated on Recurrence of syncope or cardiac events. An 8-year-old boy with long QT syndrome and nocturnal cardiac events caused by a KCNH2 missense mutation (G604S) had no recurrence of syncope or cardiac events over 10 months of pharmacological treatment.
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