The aim of this retrospective and prospective single-center observational study is to evaluate the correct management of adult patients with congenital heart diseas (ACHD), based on the experience of a reference center such as the Institute of Pediatric Cardiology at Policlinico Sant'Orsola Malpighi. The patients participating in this study will not be subjected to any procedures beyond normal daily clinical practice; likewise, the clinical variables that will be collected for the study are those that are commonly collected by the physician in daily clinical practice. This study therefore involves naturalistic observation of current clinical practice without the application of any kind of intervention.