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Case Reports
. 2018 Jul;23(4):e12517.
doi: 10.1111/anec.12517. Epub 2017 Nov 30.

Late-onset severe long QT syndrome

Babken Asatryan  1 , André Schaller  2 , Deborah Bartholdi  2 , Argelia Medeiros-Domingo  1
Affiliations
Case Reports

Late-onset severe long QT syndrome

Babken Asatryan et al. Ann Noninvasive Electrocardiol. 2018 Jul.

Abstract

We report a case of torsades de pointes arrhythmia as the first manifestation of congenital Long QT syndrome in a 77-year-old man with family history of sudden unexplained death. This case illustrates the importance of vigilant clinical assessment and genetic counseling in families with sudden death in order to identify properly asymptomatic relatives at risk for cardiac events. It also demonstrates that Long QT syndrome can still manifest with potentially fatal arrhythmias late in life in previously asymptomatic elderly patients.

Keywords: channelopathy; genetic test; long QT syndrome; sudden death.

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Figures

Figure 1
Figure 1
Electrocardiographic characterization of a patient with long QT syndrome. (a) recording of torsades de pointes, the hallmark arrhythmia of long QT syndrome, terminated after injection of magnesium sulfate. (b) 12‐lead ECG showing heart‐rate corrected Q‐T interval (QTc) of 713 ms (QT = 648 ms, heart rate = 73/min), T‐wave alternans (arrowheads), and frequent premature ventricular contractions
Figure 2
Figure 2
Family pedigree. The index patient is indicated with an arrow. The black symbol represents the affected individual. Symbols containing “n.a.” (not analyzed) indicate individuals with unknown genotype and phenotype. II.1: Sudden death at the age of 70. II.2: index patient who carries heterozygous c.1022C > T mutation in KCNQ1 gene, and was diagnosed with long QT syndrome at the age of 77 years. III.1 and III.2: unaffected daughter and son evaluated at the age of 44 and 41, respectively
Figure 3
Figure 3
Predicted topology of the Ala341Val mutation on the α subunit Kv7.1 (KCNQ1) of the IKs channel. Kv7.1 (KvLQT1) is composed of six membrane‐spanning segments (S1–S6), including a voltage‐sensing domain (VSD) (S1–S4), a pore loop, two cytoplasmic loops (S2–S3 and S4–S5), a NH 2 and a COOH terminus domains. The Kv7.1 subunit interacts with accessory β subunit/MinK (KCNE1) and the A‐kinase anchoring protein (AKAP) (Yotiao) to form the functional IKs channel complex. Conventional 1‐letter abbreviation (A, alanine; V, valine) is used to show the KCNQ1‐Ala341Val substituted identified in this case
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