Circulation Journal
Online ISSN : 1347-4820
Print ISSN : 1346-9843
ISSN-L : 1346-9843
Clinical Investigation
Q-T Peak Dispersion in Congenital Long QT Syndrome
Possible Marker of Mutation of HERG
Masaru InoueMasami ShimizuHidekazu InoMasato YamaguchiHidenobu TeraiKenshi HayashiMasaru KiyamaKenji SakataTatsumi HayashiHiroshi Mabuchi
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2003 Volume 67 Issue 6 Pages 495-498


Congenital long QT syndrome (LQTS) is caused by mutations in various cardiac potassium or sodium channel genes, with 6 different genotypes thus far identified. However, it is unknown whether these genotypes can be differentiated by QT variables. The electrocardiograms obtained from 16 patients with a mutation in KCNQ1 (LQT1), 7 patients with a mutation in HERG (LQT2) and 20 control subjects were analyzed. The corrected QT interval (QTc), Q-T peak interval (QTpc) and dispersion of QTc or QTpc were measured in 6 precordial leads. The corrected interval from T peak to T end (Tpec) was measured in lead V5. The maximum QTc, QTc dispersion, and Tpec were significantly increased in the LQT1 and LQT2 patients than in the controls. However, there were no significant differences in these indices between the LQT1 and LQT2 patients. In contrast, QTpc dispersion was significantly increased in the LQT2 patients (78±25 ms) compared with the LQT1 patients (29±15 ms) and controls (26±19 ms). These results suggest that increased lag of the peak of the T wave in each precordial lead (QTpc dispersion) may be a possible index to differentiate LQTS patients with HERG mutation from those with KCNQ1 mutation. (Circ J 2003; 67: 495 - 498)

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