Congenital Long QT 3 in the Pediatric Population

Department of Pediatrics, Steven and Alexandra Cohen Children's Medical Center of New York, New Hyde Park, USA.
The American journal of cardiology (Impact Factor: 3.28). 02/2012; 109(10):1459-65. DOI: 10.1016/j.amjcard.2012.01.361
Source: PubMed


There is insufficient knowledge concerning long-QT (LQT) 3 in the pediatric population to determine whether recommendations for more aggressive therapy in these patients are appropriate. An international multicenter review of 43 children with cardiac sodium channel (SCN5A) mutations and clinical manifestations of LQT syndrome without overlap of other SCN5A syndromes was undertaken to describe the clinical characteristics of LQT3 in children. Patients were aged 7.6 ± 5.9 years at presentation and were followed for 4.7 ± 3.9 years. There was significant intrasubject corrected QT interval (QTc) variability on serial electrocardiography. Forty-two percent presented with severe symptoms or arrhythmia and exhibited longer QTc intervals compared to asymptomatic patients. None of the 14 patients who underwent primary prevention implantable cardioverter-defibrillator (ICD) implantation received appropriate shocks in 41 patient-years of follow-up, while 2 of 6 patients who underwent secondary prevention ICD implantation received appropriate shocks in 30 patient-years of follow-up. Half of patients who underwent ICD implantation experienced inappropriate shocks or ICD-related complications. Mexiletine significantly shortened the QTc interval, and QTc shortening was greater in patients with longer pretreated QTc intervals. Two ICD patients with frequent appropriate ICD shocks showed immediate clinical improvement, with elimination of appropriate ICD shocks after mexiletine loading. In conclusion, severe symptoms are common in children with LQT3 and are associated with longer QTc intervals. ICD implantation is associated with significant morbidity. Mexiletine shortens the QTc interval, and it may be beneficial.

1 Follower
10 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Opinion statement: The inherited channelopathies are a rare, heterogeneous group of diseases with widely variable clinical presentations and courses. Systematic clinical and experimental work has led to identification of disease-causing genetic mutations and their biophysical manifestation. The process by which the knowledge base is developed, from genetic mutation, to cardiac myocyte, to whole heart, and finally to clinical presentation, has dramatically expanded our understanding of these diseases. Most importantly, we can now begin to comprehend how small changes at the genetic level can dramatically influence a patient's clinical course.
    No preview · Article · Aug 2012 · Current Treatment Options in Cardiovascular Medicine
  • [Show abstract] [Hide abstract]
    ABSTRACT: Opinion statement: The vast majority of implantable cardioverter defibrillators (ICDs) continue to be implanted in the adult population. Accordingly, manufacturers develop devices and leads primarily for the adult population. Whilst the number of ICDs implanted in children is small in comparison, the potential benefits are large to this group. It is a common frustration among pediatric cardiologists whom implant devices that impressive technological developments continue to be developed for the adult population; as the population of children with ICDs is small, robust clinical studies often lag behind. By necessity, pediatric cardiologists and cardiothoracic surgeons have developed innovative techniques utilizing adult components in unusual configurations for children with complex congenital heart disease. As in the adult population, inappropriate shocks are one of the most limiting and concerning complications in the use of ICDs. Unfortunately, as will be discussed below, children are at increased risk of inappropriate shocks when compared with adults. The true impact of inappropriate shocks is increasingly being realized, and much of the focus in management of children with ICDs surrounds the prevention of inappropriate shocks.
    No preview · Article · Aug 2012 · Current Treatment Options in Cardiovascular Medicine
  • [Show abstract] [Hide abstract]
    ABSTRACT: Opinion statement: Arrhythmias are an important cause of morbidity and mortality in children. Despite recent technological advances in treatment, pharmacologic therapy remains the most common treatment modality for pediatric arrhythmias. The choice of antiarrhythmic agent, the duration of therapy, and the dosing schedule depend on multiple factors including the recurrence risk and the arrhythmia burden (the latter being determined by the hemodynamic effect of the arrhythmia), and the frequency and duration of episodes. As with all pediatric medications, consideration must be given to the drug formulation, palatability, adverse effects and adherence issues. There are very few randomized trials available to guide the choice of therapy for pediatric arrhythmias, and thus treatment options often reflect physician or institutional preferences. Although various classification schemes exist, we classify antiarrhythmic agents based on their primary site of action: atrial muscle/accessory pathway (class IA, IC, and III agents); the atrioventricular node (beta-blockers, calcium channel blockers, digoxin, and class III agents); or ventricular muscle (class I and III agents). This type of categorization assists in the approach to treatment required for each type of arrhythmia encountered.
    No preview · Article · Aug 2012 · Current Treatment Options in Cardiovascular Medicine
Show more