Sternal opening width is associated with increased risk for capillary leak syndrome and death in neonates and infants after cardiac surgery with delayed sternal closure

Capillary leak syndrome is a serious postoperative complication in neonates and infants after open-heart surgery for CHD. The aim of this study was to investigate the relationship between sternal opening width and the occurrence of capillary leak syndrome in patients undergoing cardiac surgery with delayed sternal closure.We retrospectively analysed the clinical data of neonates and infants (aged < 12 months) who underwent open-heart surgery with delayed sternal closure at our institution between January 2016 and December 2021. Patients were categorised into groups based on postoperative diagnosis of capillary leak syndrome, defined as delayed sternal closure exceeding 3 days in combination with established clinical criteria. Stent length per kilogram (SL/kg) was calculated as the ratio of the sternal stent length to the patient"s body weight (mm/kg).Of the 164 patients, 12 (7.3%) met capillary leak syndrome criteria. Capillary leak syndrome patients had higher median SL/kg (19.7%, <i>p</i> = 0.02), higher prenatal diagnosis rate (31.3%, <i>p</i> = 0.03), longer cardiopulmonary bypass time (24 min, <i>p</i> = 0.01), inotrope use (155 hours, <i>p</i> < 0.001), drainage time (99 hours, <i>p</i> < 0.001), duration of invasive ventilation (168 hours, <i>p</i> < 0.001), delayed sternal closure (3.8 days, <i>p</i> < 0.001), postoperative paediatric ICU length of stay (8.0 days, <i>p</i> < 0.001), and total hospital length of stay (8.5 days, <i>p</i> = 0.002). Nine deaths occurred, three of which were in the capillary leak syndrome group.Univariate analysis identified higher SL/kg (OR:1.17, 95% CI:1.00-1.38) as a risk factor for postoperative mortality. Multivariate analysis identified SL/kg (OR:1.28, 95% CI:1.05-1.58) and prolonged paediatric ICU length of stay (OR:1.11, 95% CI:1.03-1.21) as significant risk factors for mortality.In conclusion, capillary leak syndrome after open-heart surgery in neonates and infants with delayed sternal closure is associated with postoperative morbidity. Increased SL/kg and prolonged paediatric ICU length of stay are associated with mortality. Importantly, patients requiring wider sternal separation often present with greater haemodynamic instability and require more extensive postoperative support and prolonged intensive care. Thus, SL/kg may function as a surrogate marker of overall illness severity, rather than as an independent risk factor for capillary leak syndrome or mortality.