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Editorial Congenital Heart Disease Arrhythmia in Congenital Heart Disease – A Current Perspective Louisa O’Neill, Henry Chubb and Mark D O’Neill Division of Imaging Sciences and Biomedical Imaging, King’s College London, London, UK; Department of Cardiology, St. Thomas’ Hospital and Evelina Children’s Hospital, London, UK Abstract Cardiac arrhythmia is a common presenting complaint in adult patients with treated congenital heart disease. (CHD) Advances in surgical and electrophysiological intervention, combined with improved mechanistic understanding, mean that effective arrhythmia treatment is a realistic expectation for this challenging patient group. This short commentary outlines the current paradigm for arrhythmia management across the spectrum of adult congenital heart disease. Keywords Arrhythmia, ablation, congenital heart disease Disclosure: Louisa O’Neill, Henry Chubb and Mark D O’Neill have nothing to disclose in relation to this article. No funding was received in the publication of this article. This article is a short opinion piece and has not been submitted to external peer reviewers. Disclaimer: The views expressed here are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit. Received: 25 March 2016 Published Online: 10 May 2016 Citation: European Journal of Arrhythmia & Electrophysiology, 2016;2(1):22–3 Correspondence: Henry Chubb, Division of Imaging Sciences and Biomedical Engineering, King’s College London, 4th Floor North Wing, St. Thomas’ Hospital, 249 Westminster Bridge Road, London, SE1 7EH, UK. E: Advances in surgical technique over the last two decades have heralded a dramatic improvement in survival rates in those born with congenital heart disease (CHD). With current methods, more than 85% of paediatric patients undergoing surgical repair survive into adulthood, 1 and there are now at least 1.2 million people living in Europe with CHD, 2 of whom 50% are adults. These patients pose unique challenges to the cardiologists who treat them, and arrhythmias represent one of the leading causes of morbidity in this group. It is estimated that more than half of adults with severe CHD will experience atrial arrhythmia (AA) by the age of 65. 3 Despite the headline figures, there has been a general fall in prevalence of arrhythmia within lesion groups. This is likely to be related to the evolution of surgical procedures and the advent of catheter-based interventions, reducing surgical scar burden. However, 20% of hospital admissions in adults with repaired CHD continue to be arrhythmia- related 4 and they represent a diverse group of patients who differ from the general population both in terms of the mechanism of their arrhythmia and its treatment with respect to catheter ablation. The ongoing development of catheter-based technologies has made the treatment of arrhythmia in the congenital population an exciting, evolving and rewarding field. The type and prevalence of arrhythmia in CHD varies according to congenital cardiac diagnosis and management course. In general though, the development of arrhythmias can be broadly attributed to: 1. 2. 22 conduction abnormalities inherent to the lesion; the long-term effects of adverse haemodynamic loading resulting in chamber remodelling, hypertrophy and fibrosis,;or 3. the arrhythmogenic effects of prior surgical incisions and consequent scar formation. AAs are more common than ventricular arrhythmias across the spectrum of CHD, particularly in those who have undergone extensive atrial surgery such as atrial switch procedures (Mustard/Senning operation). All AAs, including focal and reentrant atrial tachycardia and atrial fibrillation (AF), tend to occur more frequently in CHD than in the general population, but intra-atrial re-entry tachycardia (IART) is of particular concern, often presenting many years after surgical correction. The majority of IARTs are right sided circuits utilising the cavotricuspid isthmus, as in the non CHD population, but up to 40% have right or left sided circuits within scar or incisional regions. 5 Ventricular arrhythmias occur mainly in the setting of more complex defects, including those with univentricular circulation, or in those with abnormal surgical and loading conditions of the ventricle, such as Tetralogy of Fallot or left ventricular outflow obstruction. Many patients may initially be asymptomatic from their arrhythmia, potentially eluding timely diagnosis. However for some, particularly those with univentricular circulation, the onset of AA can precipitate rapid haemodynamic deterioration making prompt recognition and cardioversion of paramount importance. Long-term management is often difficult, with pharmacological treatment rarely succeeding in achieving adequate arrhythmia control without substantial drug-related side-effects. Early catheter intervention should therefore be considered in all cases following a patient-specific evaluation of risk/benefit, and particularly for those in whom arrhythmia is associated with haemodynamic compromise. TOU C H ME D ICA L ME D IA