This multicentre study is to validate prediction modeling for the ACHD population undergoing cardiac surgery. The validation of this prediction model will support and generalize its use as a risk stratification tool in the ACHD population.

The prediction model resulted from a preceding study, which uniquely based on comorbidities, was developed using 783 adults (>16 years) who underwent surgery for congenital heart disease at Toronto General Hospital (TGH) during 2004-2015. It identifies five pre-operative variables, namely presence of cognitive impairment, hepatic function, >3 chest incisions, anatomy diagnosis, and Body Mass Index <20 and >28, as significant predictors of composite adverse outcomes such as in-hospital mortality, prolonged ventilation (exceeding 7 days) and acute kidney injury.

This newly prediction model developed in a single-center has only been internally validated. It requires further external validation to demonstrate its utility in ACHD populations who require cardiac surgery in other cardiac institutions both nationally and internationally.

Inclusion Criteria:

• all ACHD patients >16 years of age undergoing cardiac surgery requiring an open sternotomy or thoracotomy and cardiopulmonary bypass (CPB) or CPB standby at TGH and the collaborating institutions from April 2019.

Exclusion Criteria:

• CHD patients <16 years of age
• ACHD patients undergoing chest wall debridement and chest re-explorations for bleeding
• Non-cardiac surgery procedures and cardiology laboratory interventions

All ACHD patients undergoing cardiac surgery in TGH and the other collaborating cardiac centers.