BackgroundLimited data exist regarding outcomes of delayed sternal closure (DSC) in adults with congenital heart disease (ACHD). MethodsWe reviewed 159 ACHD patients undergoing cardiac operation from 1993 to 2023 who required DSC (open sternum at the end of operation, n = 112) or sternum emergently reopened (n = 47). Regression models were performed to determine factors associated with outcomes. ResultsOf 112 patients undergoing DSC, 87 patients (77.6%) underwent DSC ≤4 days and 25 patients (22.3%) >4 days. The most common operations were valve (n = 35 [31.2%]), aortic (n = 33 [29.4%]), and right ventricular outflow tract procedures (n = 23 [20.5%]). Median time to chest closure was 2 days (interquartile range, 1-5 days). Apart from sex, baseline characteristics were similar between DSC groups. A stepwise increase in early mortality was observed from DSC ≤4 days to DSC >4 days (6.8% vs 32%), as well as the incidence of early complications, except sternal infection. Risk factors associated with early mortality were age (P = .02), DSC >4 days (P < .001), hemodynamic indication (P = .03), and single ventricle (P = .02). On multivariable analysis, lower ejection fraction (P = .04), hemodynamic indication (P = .02), single ventricle (P = .004), and diabetes mellitus (P = .03) were predictors of prolonged time to chest closure. Among hospital survivors, late survival was similar between patients undergoing DSC ≤4 days vs >4 days (P = .48). ConclusionsA brief duration of DSC in ACHD patients is associated with low morbidity and mortality. Higher early mortality and complications were observed among patients who did not achieve chest closure within 4 days.