Mutation Site Dependent Variability of Cardiac Events in Japanese LQT2 Form of Congenital Long-QT Syndrome

Iori Nagaoka; Wataru Shimizu; Hideki Itoh; Satoshi Yamamoto; Tomoko Sakaguchi; Yuko Oka; Keiko Tsuji; Takashi Ashihara; Makoto Ito; Hidetada Yoshida; Seiko Ohno; Takeru Makiyama; Yoshihiro Miyamoto; Takashi Noda; Shiro Kamakura; Masaharu Akao; Minoru Horie

doi:10.1253/circj.72.694

Clinical Investigation

Mutation Site Dependent Variability of Cardiac Events in Japanese LQT2 Form of Congenital Long-QT Syndrome

Iori Nagaoka, Wataru Shimizu, Hideki Itoh, Satoshi Yamamoto, Tomoko Sakaguchi, Yuko Oka, Keiko Tsuji, Takashi Ashihara, Makoto Ito, Hidetada Yoshida, Seiko Ohno, Takeru Makiyama, Yoshihiro Miyamoto, Takashi Noda, Shiro Kamakura, Masaharu Akao, Minoru Horie

Author information

Iori Nagaoka
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Wataru Shimizu
Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center
Hideki Itoh
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Satoshi Yamamoto
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Tomoko Sakaguchi
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Yuko Oka
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Keiko Tsuji
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Takashi Ashihara
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Makoto Ito
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
Hidetada Yoshida
Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
Seiko Ohno
Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
Takeru Makiyama
Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
Yoshihiro Miyamoto
Laboratory of Molecular Genetics, National Cardiovascular Center
Takashi Noda
Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center
Shiro Kamakura
Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center
Masaharu Akao
Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
Minoru Horie
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science

Keywords: Arrhythmia, Long-QT syndrome, QTc interval, Risk factors, Torsade de pointes

JOURNAL FREE ACCESS

2008 Volume 72 Issue 5 Pages 694-699

DOI https://doi.org/10.1253/circj.72.694

Details

Abstract

Background In the LQT2 form of long QT syndrome (LQTS), mutation sites are reported to correlate with clinical phenotypes in Caucasians, but the relationship in Asian patients remains unknown. The present study was designed to determine whether the location of KCNH2 mutations would influence the arrhythmic risk in LQT2 patients. Methods and Results In 118 genetically-confirmed LQT2 patients (69 families, 62 KCNH2 mutations), the ECG parameters, Schwartz scores, and the incidence of cardiac events, defined as syncope, aborted cardiac arrest, and sudden cardiac death, were evaluated. To examine the effect of mutation sites, the participants were divided accordingly: pore (n=56) and non-pore (n=62) groups. The corrected QT_end interval was significantly greater in the pore than in the non-pore group (QTc; 522±63 ms vs 490±49 ms, p=0.002). In this study, the clinical course of each of the probands did not differ according to the mutation sites, whereas non-probands carrying the pore site mutation experienced their first cardiac events at significantly younger age than those with the non-pore site mutation (log-rank, p=0.0005). Conclusions In a Japanese LQT2 cohort, family members with the pore site mutation were at higher arrhythmic risk than those with the non-pore site mutation. (Circ J 2008; 72: 694 - 699)

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