Long-term electrocardiographic follow-up from childhood of an adult patient with Brugada syndrome associated with sick sinus syndrome.

We had the unique opportunity of following the electrocardiographic (ECG) course of a 13-year-old male with sinus dysfunction and atrial flutter who subsequently developed a Brugada-type ECG pattern associated with sick sinus syndrome at 25 years old. Family history showed that the patient's mother and maternal grandfather suddenly died while sleeping at night. When the patient was 13 years old, he lost consciousness after running a marathon. The patient was diagnosed with sinus dysfunction and atrial flutter, and he underwent pacemaker implantation at 15 years old. ECG examinations performed between 13 and 20 years old showed incomplete right bundle branch block and ST elevation with early depolarization. On ECG examinations performed when the patient was 21 years old and thereafter, the V(2) lead always showed a saddleback-type ST elevation. At 25 years old, the late potential was positive and the electrophysiological study induced ventricular fibrillation. A challenge test with pilsicainide showed remarkable ST elevation by the V(2) lead. The 24-h Holter ECG monitoring showed remarkable ST elevation after eating a snack and during night time when the patient was asleep. The patient was diagnosed with Brugada syndrome and an implantable cardioverter-defibrillator was implanted. Genetic analysis did not reveal mutation of the SCN5A gene.

Long-term course and clinical characteristics of ventricular tachycardia detected in children by school-based heart disease screening.

BACKGROUND: The prognosis of ventricular tachycardia (VT) in children with overt heart disease is generally good, so the aim of this study was to review the prognosis and necessity of treatment of VT that detected by school-based heart disease screening. METHODS AND RESULTS: Of the 48 cases of pediatric VT that have been followed for 2-30 years, 17% were diagnosed at the first school-based screening test (12-lead ECG at rest) and the remainder who had premature ventricular contractions (PVC) on the resting 12-lead ECG required Holter ECG test and exercise stress ECG test to detect VT. In 90% of cases, VT in healthy children is idiopathic non-sustained VT and more than half of the present cases showed natural disappearance of the VT during follow up. In particular, cases of monomorphic PVC or maximum PVC runs less than 5 had a good prognosis. The cases of polymorphic VT and VT with heart disease continued for the long term. CONCLUSION: Treatment is unnecessary for monomorphic VT with the maximum number of salvos less than 5. The necessity for treatment depends on the symptoms and profile of the VT. The prognosis for polymorphic VT and underlying heart disease is not good and may require implantable cardioverter defibrillator.

Who is at risk for cardiac events in young patients with long QT syndrome?

The objective of this study was to determine who is at risk for cardiac events among young patients with long QT syndrome (LQTS) with or without a past history of LQTS-related cardiac events. The subjects were young patients with LQTS who had visited one of 36 hospitals from January 1997 to August 2000 in Japan. To predict the risk factors for cardiac events, stepwise regression analyses were performed for a total of 197 cases. There were 7 of 129 cases (5%) without a past history and 32 of the 68 (47%) cases with a past history of LQTS-related cardiac events that experienced new events after diagnosis (p<0.0001). Patients with a family history showed a higher incidence of symptoms both before and after diagnosis than patients with sporadic occurrence. Analyses revealed that noncompliance with medication and a lower age at diagnosis were significant predictors for the group with a past history. A negative predictive value <4 points was 100% in the group without a past history. To prevent future cardiac events, compliance with medication must be improved in those with a past history. A total LQTS score <4 points was useful to predict the absence of cardiac events in the group without a past history.

A case of fatal mitochondrial cardiomyopathy.

We report a case of mitochondrial cardiomyopathy in a Japanese boy who presented with severe cardiac heart failure and died 6 days after admission. The onset of mitochondrial cardiomyopathy often occurs very early in childhood and has a rapid downward course.

Effect of age and overweight on the QT interval and the prevalence of long QT syndrome in children.

The change in QT interval with age during childhood of normal children and children with long QT syndrome (LQTS) and the effects of body mass index on the QT interval have not been studied in detail. The prevalence of LQTS in children is not well known. We measured 3 consecutive QT and RR intervals in 4,655 children. Their electrocardiograms along with their height and weight were recorded when they were in the first grade in 1994 and again when they were in the seventh grade in 2000. The QT interval was corrected by Bazett's formula. The longer corrected QT intervals in female subjects than male subjects start at elementary school age, earlier than previously reported. Overweight did not have an impact on the uncorrected or corrected QT interval. None of the 4 children diagnosed with LQTS in the seventh grade had characteristic electrocardiographic findings of LQTS in the first grade. All 4 are nonfamilial cases. The prevalence of LQTS in children was found to be 1 of 1,164. These data suggest that abnormal electrocardiographic phenotypes in children with nonfamilial LQTS may appear during the elementary school year. The longer QT intervals in female subjects than male subjects start at the same period. No correlation was found between obesity and length of the QT interval. Finally, the prevalence of LQTS in children is greater than previously suspected.