BackgroundCoronavirus disease 2019 (COVID-19) was associated with a reduction in physical activity in children with congenital heart disease (CHD) in early 2020. Given the increased cardiovascular risk of this population, optimizing cardiovascular health behaviour is important. The aim of the study is to determine how the ongoing COVID-19 pandemic has impacted longitudinal physical activity measures in children with CHD.MethodsAs part of a prospective cohort study, children and adolescents aged 9-16 years old with moderate-to-complex CHD were recruited from British Columbia Children’s Hospital and partnership clinics across British Columbia and the Yukon territory. Daily step counts were measured continuously over 3 years (2018-2021) with Fitbit Charge 2. School status during the COVID-19 pandemic was assessed with parent- or self-report survey.ResultsA total of 102, 114, and 93 participants had valid Fitbit data during 2018, 2019, and 2020, respectively. There was a significant reduction in the annual mean step count for 2020 (8225 ± 4328 steps) compared with both 2018 (9416 ± 3770 steps) and 2019 (9533 ± 4114 steps) (P < 0.001). There was a loss of seasonal variation in physical activity, and reduced levels of physical activity persisted when most children resumed in-person schooling in September 2020.ConclusionsWe demonstrated a significant decrease in physical activity and loss of seasonal patterns in children with CHD during 2020. These findings represent a worsening of the cardiovascular risk profile in children with CHD, who are already at an increased risk of adverse cardiovascular outcomes. Mitigation strategies are needed to optimize the cardiovascular health status of children with CHD as the pandemic persists.