Life expectancy of children with congenital heart disease (CHD) has increased dramatically during the past years, due to the successes of cardiac surgery. Nearly all of these children with CHD can be operated at young age and more than 90% reach adulthood. However, many adults with CHD are life-long affected by cardiac events, particularly arrhythmias and heart failure, putting them at risk of premature death. These events have a large impact on quality of life of patients and their families and merit life-long hospital visits in a medical center specialized in adult CHD. Especially for adults with CHD patient care with a smartphone is suited because of their young age and chronic condition. So far, data are lacking on smartphone interventions in patients with CHD.