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he major causes of death of patients with hypertrophic cardiomyopathy (HCM) include sudden death, progressive heart failure, and HCM-related stroke associated with atrial fibrillation. Of these, sudden cardiac death is the most common in young patients. [1][2][3][4] Sudden death in HCM is associated with many factors: a family history of sudden death, the presence of an obstructive region, abnormal blood pressure (BP) response during exercise, increased left ventricular wall thickness, and the presence of an increased QT interval, ventricular arrhythmia, or myocardial bridging of the left anterior descending artery. 1,[3][4][5] A study on sudden death in patients with HCM and a mean age of 28 years demonstrated a circadian pattern over a 24-h period, with a prominent midmorning peak and a less striking early-evening peak. 5 The peak frequency of sudden death after awakening in the morning is similar to adult subjects with or without coronary artery disease. [6][7][8] Circulation Journal Vol.68, August 2004 The data regarding circadian variability suggest that the autonomic nervous system plays an important role in the genesis of sudden cardiac death, not only in coronary artery disease, 6,9,10 but also in HCM. [11][12][13][14][15][16] Many indices using 24-h Holter monitoring have been evaluated in HCM and those reports have described altered sympathetic and/or vagal activity; 2,5,[10][11][12][13][14][16][17][18][19] the results, however, are controversial, and the data for children are scant, despite the fact that sudden death primarily occurs in children and adolescents.An abnormal BP response during exercise has been reported as one of the predictive factors of sudden cardiac death in HCM, 20-22 especially in young patients, 23 but sudden death also occurs during sedentary periods or mild activity. 5 Recently, ambulatory BP monitoring has been used to manage childhood hypertension, [24][25][26][27][28] with results showing that BPs in childhood are quite different for the various time periods (resting, at school, at home, and sleeping). 26 These results suggest that the BP response to daily life activities should be investigated in children with HCM. Therefore, the purpose of this study was to determine the presence or absence of altered autonomic activity and abnormal BP response to daily life activities, and to predict sudden cardiac death in young patients with HCM. Methods SubjectsAll patients with a diagnosis of HCM made before 19 years of age, and who were being treated at the Depart- Background Sudden cardiac death commonly occurs in young patients with hypertrophic cardiomyopathy (HCM); however, their heart rate variability (HRV) and blood pressure (BP) response to daily life activities is not well known. Methods and Results HRV and ambulatory BP monitoring were performed in 20 patients (age range: 7-21 years) and 57 age-matched healthy volunteers (age range: 10-22 years). Time domain variables and spectral data were obtained at hourly intervals throughout the day. To determine the BP response to d...

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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...

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