Congenital heart diseases (CHD) are a variety of heart conditions that afflict an increasing number of adults. Significant advances in paediatric cardiology and paediatric cardiac surgery over the past decades have modified mortality trends and currently nearly 90% of children born with these defects reach adulthood. As a result, there are nowadays more adults than children living with CHD. However, these are repaired hearts with residual lesions that may require subsequent interventions over time and that are exposed to long-term complications, predominantly arrhythmias and heart failure. Moreover, the particular physiology of some CHD has a multisystemic impact that may lead to complications in organs far from the heart. Some of these cardiovascular and non-cardiovascular complications are life-threatening and require intensive care unit (ICU) admission. Such is the case of severe arrhythmias, acute pulmonary oedema, haemoptysis due to major aortopulmonary collateral arteries, acute cholecystitis due to gallstones in patients with cyanosis, infective endocarditis or stroke, among others. Approximately 16% of patients with adult congenital heart disease (ACHD) will require an ICU admission by the age of 40,1 particularly those with more complex forms of CHD. Management of these patients during this critical situation is challenging and requires a complete understanding of the anatomy, physiology and associated comorbidities to tailor an individualised approach that achieves the optimal care.

However, the literature confronting this troublesome scenario is scarce and mostly focused on postelective cardiac surgery ICU management. In 2007 Price et al 2 reported the resource utilisation and predictors of mortality in critically ill patients with ACHD in a single tertiary …