ong QT syndrome (LQTS) is a rare disease characterized by prolonged ventricular repolarization and a high risk for cardiac events including sudden cardiac death. 1 Mutations causing LQTS have been identified in 5 genes, each encoding a cardiac ion channel and its regulatory subunit. [2][3][4][5] Most cases of LQTS that come to the attention of physicians are either symptomatic or familial. [6][7][8] Recent studies have reported that life-threatening arrhythmias in LQTS patients tend to occur under specific circumstances (eg, exercise, emotion, and sleep/rest without arousal) in a gene-specific manner. 9 Beta-blocker therapy is reported to be effective in preventing LQTS-related cardiac events in these patients, but they continue to occur while patients are on the prescribed medication. 10 A recent report has reported a gender reference in the electrocardiographic (ECG) response to -blockers in patients with LQTS. 11 A screening program conducted for Japanese children (1st, 7th and 10th grades) has uncovered large numbers of children with LQTS both without a family history and without a history of LQTS-related cardiac events at the Circulation Journal Vol.67, December 2003 time of diagnosis. 12-14 The initiation of drug therapy for these young patients is controversial because many pediatric cardiologists consider that few young LQTS patients without a past history have experienced new cardiac events after diagnosis. The objective of the present study, then, was to examine the characteristics of Japanese pediatric patients with LQTS and to determine the predictive factors for cardiac events after diagnosis in these young patients with and without a past history of cardiac events.
Methods
Subjects and DataA questionnaire was sent to 111 hospitals where the trustee(s) of the Japanese Society of Pediatric Cardiology and Cardiac Surgery were working. Subjects were those who visited one of those hospitals from January 1997 to August 2000 and who were less than 20 years old at the time of diagnosis. Characteristics of the subjects obtained from the survey included the following: past history of LQTS-related cardiac events, ECG findings, clinical and family history for diagnosis of LQTS according to the criteria of Schwartz et al, 15 cardiac events during the period after diagnosis and medication. When medication was prescribed, those patients were re-surveyed for compliance. Subjects were classified into 2 groups on the basis of the presence or absence of a past history of LQTS-related cardiac events at the time of diagnosis. The index events for diagnosis were classified as follows: (1)
Who Is at Risk for Cardiac Events in Young PatientsWith Long QT Syndrome?Masao Yoshinaga, MD*; Masami Nagashima, MD; Toshimitsu Shibata, MD; Ichiro Niimura, MD; Mitsuo Kitada, MD; Toshiaki Yasuda, MD; Mari Iwamoto, MD; Junko Kamimura, MD; Mayu Iino, MD; Hitoshi Horigome, MD; Masashi Seguchi, MD; Sumi Aiba, MD; Naomi Izumida, MD; Takashi Kimura, MD; Hiroya Ushinohama, MD; Junichiro Nishi, MD*; Yukiharu Kono, MD*; Yuichi Nomura, MD*; Ko...
