As support and interventions for congenital heart disease (CHD) improved, more than 90% of children survive to adulthood (Mulder, Neth Heart J. 20:505–508, 2012). Estimates of prevalence suggest that the population of adults with CHD in the United States is 1.4 million individuals, comprising the majority of the 2.4 million adults and children with CHD (Gilboa et al., Circulation. 134:101–109, 2016). With improving screening and management, clinicians are more likely to encounter an adult with a known diagnosis of clinically significant adult CHD as opposed to one whose diagnosis in unknown. Diagnostic dilemmas may still arise in the setting of incomplete recall or records of a patient’s prior diagnoses. In all settings where CHD may be a factor in patient management, early consultation or referral involving a patient’s prior cardiology care team is advantageous and essential because of the heterogeneity of CHD manifestations, interventions, and management strategies.