Exertional syncope has been suggested to correlate with a cardiac aetiology, particularly when occurring in mid-stride. The aim of the study is to evaluate the incidence of cardiac disease among children presenting with exertional syncope, determine the influence of timing within activity, and determine the utility of genetic testing and implantable event monitors in the evaluation of cardiac syncope. The patients ≤18 years old with exertional syncope who underwent exercise stress testing between 2008 and 2019 were retrospectively included. Patients were assessed to be in one of three groups: mid-exertion (mid-stride syncope), peri-exertion (syncope during activity but not moving), and post-exertion (within minutes of the activity). A total of 334 patients were included; 46 % were mid-exertion, 18 % were peri-exertion, and 36 % were post-exertion. Thirteen patients (3.8 %) were diagnosed with cardiac syncope; n = 9 (69 %) mid-exertion. Only mid-exertional syncope was significantly associated with a cardiac diagnosis (OR: 2.6). Cardiac diagnoses included inherited arrhythmia syndromes (n = 9), abnormal coronary origins (n = 2), and supraventricular tachycardia (n = 2). Only catecholaminergic polymorphic ventricular tachycardia (n = 5) was associated with mid-exertional syncope (OR: 1.4). The definitive diagnostic test was exercise testing (n = 8), echocardiogram (n = 2), genetic testing (n = 1), ambulatory monitor (n = 1), and EKG (n = 1). Mid-stride syncope was more likely to result in a cardiac diagnosis, and exercise testing is the most common definitive test as catecholaminergic polymorphic ventricular tachycardia was the primary aetiology of exertional syncope in our cohort. Implantable event monitors and genetic testing could be helpful in ruling out cardiac disease.

The Pediatric and Congenital Electrophysiology Society (PACES) is a non-profit organisation comprised of individuals dedicated to improving the care of children and young adults with cardiac rhythm disturbances. Although PACES is a predominantly North American-centric organisation, international members have been a part of PACES for the last two decades. This year, PACES expanded its North American framework into a broadly expansive international role. On 12 May, 2015, paediatric electrophysiology leaders from within the United States of America and Canada met with over 30 international paediatric electrophysiologists from 17 countries and five continents discussing measures to (1) expand PACES’ global vision, (2) address ongoing challenges such as limited resource allocation that may be present in developing countries, (3) expand PACES’ governance to include international representation, (4) promote joint international sessions at future paediatric EP meetings, and (5) facilitate a global multi-centre research consortium. This meeting marked the inception of a formal international collaborative spirit in PACES. This editorial addresses some solutions to breakdown the continental silos paediatric electrophysiologists have practiced within; however, there remain ongoing limitations, and future discussions will be needed to continue to move the PACES global international vision forward.

In adults with Wolff-Parkinson-White syndrome, the likelihood of sudden death can be estimated based upon the presence or absence of symptoms. Comparable data in children do not exist. To date, therefore, invasive risk stratification has been used to guide management regarding radiofrequency ablation in symptomatic children. As the safety of electrophysiology study and radiofrequency ablation in children has improved, asymptomatic patients have been referred more commonly for invasive risk stratification. We sought to compare the findings from electrophysiologic studies in symptomatic children with Wolff-Parkinson-White syndrome to the findings in asymptomatic children with Wolff-Parkinson-White pattern on their electrocardiogram. Thus, we compared the findings from electrophysiologic studies carried out in patients seen at Stanford University and University of California, San Francisco, from April 1999 to February 2001 with a preexcitation pattern on their electrocardiogram. The patients were divided into three groups: 23 asymptomatic patients studied for risk stratification, 19 patients who presented with syncope, and 77 patients presenting with documented supraventricular tachycardia. Data were collected for commonly accepted invasive criterions for stratification of risk: an effective refractory period of the accessory pathway less than 270 ms, multiple pathways, septal location of pathway, and inducibility of supraventricular tachycardia. Groups were compared by chisquare. No differences were found between the groups for any of the variables. These data suggest that risk factors for sudden death, developed in studies of adult patients, are not clearly applicable to children. Further studies are needed better to define the indications for study and ablation in children.

We describe the electrophysiological studies undertaken in four patients with atrioventricular nodal reentry tachycardia in the setting of concordant atrioventricular and discordant ventriculo-arterial connections (transposition). Radiofrequency ablation was attempted in three, all with success. Clear evidence of dual antegrade pathways through the atrioventricular node was present in only one of the four, but other characteristics of discrete fast and slow pathways into the atrioventricular node were present in all. Atrioventricular nodal reentry tachycardia was inducible in all. In the three patients in whom ablation was attempted, the application of radiofrequency energy to the low medial regions of the systemic venous atrium (morphologically left) consistently caused junctional accelerated rhythm, but these lesions were not successful in eliminating the tachycardia. Successful radiofrequency ablation required a retrograde approach to the region of the slow pathway in the pulmonary venous atrium (morphologically right).