European Heart Journal Advance Access originally published online on September 4, 2006
European Heart Journal 2006 27(20):2382-2384; doi:10.1093/eurheartj/ehl223
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Short QT syndrome and arrhythmogenic cardiac diseases in the young: the challenge of implantable cardioverter-defibrillator therapy for children
1 Institute of Cardiology, University of Bologna, Policlinico S. Orsola, Azienda Ospedaliera S. Orsola-Malpighi, via Massarenti 9, Bologna 40138, Italy
2 Department of Pediatric Cardiology, Azienda Ospedaliera S. Orsola-Malpighi, via Massarenti 9, Bologna 40138, Italy
* Corresponding author. Tel: +390 51349858; fax: +390 51344859. E-mail address: cardio1{at}med.unibo.it
This editorial refers to ‘Short QT syndrome: clinical findings and diagnostic therapeutic implications’
by C. Giustetto et al., on page 2440
Giustetto et al.1 have reported the largest available study of patients affected by short QT syndrome, an extremely rare genetic ion channel disease that has only recently been identified and described.2,3 The results of this multicentre study reinforce concepts gleaned from previous reports. Short QT syndrome is a genetic arrhythmogenic disease with a high risk of both syncope and sudden death throughout life. The study was based on data from 25 patients belonging to eight affected families, plus a further four sporadic cases. Although syncopes were reported, cardiac arrest was the most common event and often prompted the initial diagnosis of short QT syndrome. Notably, sudden death events occurred in the first year of life, as well as in adolescent age and adulthood. Moreover, other cases of sudden death were traced in apparently healthy family members (usually younger than 40 years) for whom no ECG was available. Thus, this new study reinforces the concept that sudden death is the most relevant clinical manifestation of short QT syndrome and that these events may occur in infants and other children.
Short QT syndrome is now included among the set of arrhythmogenic diseases that can lead to sudden death during infancy and childhood (Table 1). In all these diseases, an implantable cardioverter-defibrillator (ICD) is currently proposed for prevention of sudden death in high-risk patients.4 In most of the diseases (those with purely electrical abnormalities and otherwise normal systolic ventricular function), sudden death due to ventricular tachyarrhythmias is the dominant cause of premature death and alone accounts for almost all the difference in life expectancy in comparison with healthy subjects of comparable age.5 Therefore, the possibility to terminate potentially life-threatening episodes of malignant ventricular tachyarrhythmia by an electrical shock from an ICD has become increasingly attractive, especially in view of the generally insufficient evidence of protective effects of pharmacological interventions. However, indications to ICDs in children entail a series of important issues.
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ICDs were conceived and initially used for patients with a very different clinical profile [i.e. coronary artery disease (CAD) or dilated cardiomyopathy occurring at an average age of around 50–60 years]. Unsurprisingly, children still seem to account for <1% of all patients implanted with an ICD.6 However, improvements in clinical and genetic detection of arrhythmogenic cardiac diseases and use of family screening programmes are likely to increase the number of young subjects for whom an ICD implant has to be considered due to high risk of sudden death.
ICD implantation during childhood remains a technical challenge for several reasons. Despite an impressive reduction in device size, there are still technical problems linked to small body and heart size, difficult vascular access, and the need for ongoing modifications of the implant system owing to growth.6–8 Therefore, implant of a defibrillator in young children necessitates a high degree of technical complexity and high rates of lead complications have to be expected. Dedicated techniques for ICD implants at very young ages (even in the first year of life) are being developed in highly specialized centres.9 These techniques adopt an individualized approach to avoid use of transvenous high-energy leads. The possibility of developing devices that avoid intracardiac leads altogether (leadless ICDs) is a promising technological option that could help reduce long-term complications of ICD implants in young children.5
In adolescents, body size no longer creates difficulties for implantation. However, there is a need to implant an ICD system equipped with leads that can remain reliable for many years or decades. This consideration suggests the possibility of implanting, when appropriate, relatively simple ICDs (e.g. single- rather than dual-chamber devices) in order to minimize the risk of long-term lead-related complications.5
Another issue regards psychosocial acceptance of the device by the young patients and their families. Remarkably, Giustetto et al.1 have reported that 10 of the 26 potential ICD candidates in their series of short QT syndrome patients refused the implant. One relevant problem is likely to be the fear of a compromised quality of life following ICD implant. Furthermore, obstacles to the acceptance of an ICD may be magnified if the implant is proposed for primary prevention of sudden death in a high-risk patient (who has never experienced a malignant ventricular tachyarrhythmia). In general, psychological distress, depression, anxiety, and poor quality of life after an ICD implant are frequently linked to device discharges, especially if repeated and inappropriate (for sinus tachycardia, supraventricular tachyarrhythmias, or T-wave oversensing, which is a consistent problem in short QT syndrome). Younger patients run the highest risk of psychological distress.6,10 Dedicated programs and interventions need to be developed to improve the quality of life of the most vulnerable patients. During ICD follow-up, electrophysiologists should take advantage of dedicated device algorithms to improve rhythm discrimination, so as to reduce inappropriate interventions.5
Additionally, young patients and their families are likely to be particularly discouraged by manufacturers' notifications of device malfunctions. In the last few years, both patients' and physicians' confidence in ICD therapy has been threatened by a series of recalls and warnings.11,12 Occasionally, the malfunctions have led to inability to deliver shock therapy.13 Such cases have attracted the media spotlight and have troubled patients who have been advised to replace previously implanted devices. This situation does not make it any easier to propose an ICD implant to young patients and their families, especially in the context of primary prevention. Indeed, as a result of these rumours, the risk–benefit ratio of ICD therapy may be perceived by patients as less favourable than in the past.
As Giustetto et al. have noted, an ICD is the therapy of choice in short QT syndrome.1 The same is true for most of the other arrhythmogenic cardiac diseases listed in Table 1, whenever risk stratification indicates a high risk of sudden death. In view of the difficulties attached to use of ICDs in children, therapeutic alternatives could be extremely valuable. In this regard, short QT syndrome is rather better placed than other diseases. A pharmacological alternative is available in the form of oral quinidine. This option must however be tested for suitability in the individual patient.14 Therefore, in a very young short QT syndrome patient with a high-risk profile, oral quinidine may represent a bridge to ICD implant later in life when the technical difficulties are fewer. Oral quinidine may also offer an alternative to an ICD for older short QT syndrome patients who refuse device therapy. Unfortunately, in most of the other diseases listed in Table 1, the only available alternative to an ICD is an automated external defibrillator.4 Further studies are required to estimate the real impact of automated external defibrillators in children with such indications.
Owing to the rarity of arrhythmogenic diseases, and the difficulty in performing randomized trials, analysis of data from multicentre registries is needed to assess the long-term impact of the few therapeutic strategies that are currently available for children with these diseases, as well as the validity of current risk stratification.
In recent years, we have expanded our knowledge on various diseases (usually genetically determined ones) that expose young patients to a high risk of sudden death. Appropriate risk stratification provides a rational basis for proposing an ICD implant with a reasonable risk–benefit ratio. However, despite improvement in device technology, indications to ICD implant in young subjects remain a challenging issue. Good communication is needed between the children and their families and the attending physicians (paediatric cardiologists, cardiologists, paediatricians, as well as the electrophysiologists responsible for implantation).
Acknowledgements
We are grateful to Robin M.T. Cooke for writing assistance.
Conflict of interest: none declared.
Footnotes
The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology.
doi:10.1093/eurheartj/ehl185 
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[Abstract/Free Full Text]
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