This retrospective study sought to determine the safety and effectiveness of flecainide in children with normal hearts and those with congenital heart disease (CHD) or cardiomyopathy (CMO). Baseline and follow-up data at two pediatric cardiology sites were queried (2000-2015); a total of 175 patients (20 with CHD and two with CMO) receiving flecainide were assessed. When comparing patients with CHD to those with normal hearts, patients with CHD were younger at diagnosis (median age 19 days; IQR 3-157.5 days vs normal heart patients median age 21 days; IQR 7-172 days, p = 0.4) and severe cardiac dysfunction was more prevalent (30% in CHD patients vs 8% in normal heart patients, p = 0.009). Treatment duration did not differ between the two groups (CHD patients median duration 52 weeks; IQR 27-91.5 weeks vs normal heart patients median duration 55 weeks; IQR 32-156 weeks, p = 0.5). Cardiac dysfunction resulting in flecainide discontinuation occurred in two patients (1%), one with CHD and one without. Three patients experienced proarrhythmia (2%) and there were no cardiac arrests during follow-up. There was one death in this cohort in a patient with severe CHD and an RSV infection (<1%). Arrhythmia control did not differ between the groups (90% in CHD patients vs 77% in normal heart patients, p = 0.2). Flecainide was well tolerated in this cohort, with fewer than 3% discontinuing medication due to flecainide-associated adverse events. Contrary to adult studies, there was no difference in the incidence of adverse events between patients with normal hearts and patients with CHD. Flecainide is a safe and effective antiarrhythmic medication, even for children with underlying CHD.

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The cardiovascular benefits of habitual exercise are well documented. In the current era, more of the population is exceeding the recommendations for physical activity as the popularity of endurance events increases. Recent data have proposed a U-shaped relationship between exercise intensity and cardiovascular outcomes. Regular participation in endurance activities has been shown to result in structural and functional changes in the heart. This re-modelling may be the substrate for cardiac dysfunction or arrhythmias. The risk of sudden cardiac death may also be elevated; however, in most cases of sudden cardiac death, the cause can be linked to an underlying cardiac pathology where exercise acted as the trigger for a lethal arrhythmia. This article serves to review whether excessive exercise may result in harm in some athletes.

The genetic basis of many sudden death-related conditions has been elucidated. These include inherited arrhythmias and arrhythmogenic cardiomyopathies, termed inherited heart rhythm disorders (IHRD). Advising on and interpreting genetic testing is challenging for the general cardiologist. This has led to the development of interdisciplinary clinics for IHRD in varying stages of establishment in Canada. We sought the viewpoints and patterns of practice of Canadian IHRD experts, and assessed their ability to access genetic testing for IHRD using a national cross-sectional survey. Of 56 participants, most were physicians (68%) or genetic counselors (19%). Despite working collaboratively, most genetic counselors (59%) were either not satisfied or only somewhat satisfied with their relationships with physicians. Ninety percent of participants were involved in offering genetic evaluation, including 80% who felt that testing was usually/always accessible. Most offered genetic testing to confirm clinical diagnosis and/or direct family screening. Post-mortem genetic analysis was sought by 69% of respondents; however, a lack of retained tissue and/or poor tissue preparation hindered this process. Family screening was usually recommended in the setting of a pathogenic/likely pathogenic variant. The most commonly perceived barrier to genetic testing was cost to the healthcare system. More than a quarter of patients waited ≥ 6 months for funding. An ability to engage at-risk relatives was rated as limited/poor by 34% of participants. Despite the establishment of several interdisciplinary clinics, timely access to affordable testing, supported by strong team communication, continues to be a barrier to genetic testing in Canada.