The number of adults with congenital heart disease (ACHD) has increased over the last decades due to advancements in medical care, including interventional and surgical therapies. We are therefore more frequently challenged by the long-term consequences of palliative or corrective surgery carried out during childhood. Although patients with ACHD may develop conditions related to general cardiovascular risk factors, such as coronary artery disease, the most common complications leading to morbidity and mortality are arrhythmias, heart failure and thromboembolic events. For the management of arrhythmias, current recommendations regarding ablation and device therapy must be considered, whilst also taking into account the anatomical limitations of their congenital heart defect or surgical pathways. Heart failure treatment in acute and chronic settings must also consider the particular anatomy present, including the nature of the systemic ventricle. Treatments strategies for ACHD are typically extrapolated from the respective guidelines in non-ACHD patients, despite a lack of evidence to support this strategy. Right heart failure can be especially challenging to manage in conditions where either a systemic right ventricle or shunt lesions resulting in volume and/or pressure loading of the right ventricle are present. All physicians and cardiologists in particular should be acquainted with the most common diseases in ACHD, their complications and management regime, especially with regards to heart failure as this is a common reason for acute presentation in the emergency department.