Early Versus Delayed Bidirectional Superior Cavopulmonary Anastomosis (BSCA) in Infants: A Comparison of Outcomes

Background and aims Functionally univentricular hearts (UVH) are a relatively rare congenital heart defect and often require staged palliation leading to the Fontan circulation. The bidirectional superior cavopulmonary anastomosis (BSCA) or bidirectional Glenn shunt (BDG) is a key intermediate procedure that partially separates systemic and pulmonary circulations. Although traditionally delayed until six months of age, earlier BDG has become common. This study compared outcomes in patients undergoing BDG at six months or younger versus seven months to one year and examined time to Fontan completion (FO), outcome predictors, and the influence of early BDG in the Indian context. Methods In this retrospective observational study, 173 patients with UVH underwent BDG at age one year or younger from January 2011 to December 2020 at a single tertiary care center. Twenty-seven patients (Group A) were six months or younger, and 146 (Group B) were seven to 12 months. Preoperative, intraoperative, and postoperative data were collected, including morbidity, mortality, and follow-up assessments. The data were statistically analyzed by Fisher's exact test, Pearson's chi-square test, and Cox proportional hazards or logistic regression modeling. Results Early mortality was 6.93% (12/173). Mortality was significantly higher in Group A (5/27; 18.52%) than in Group B (7/146; 4.79%; p=0.01). On multivariate analysis, preoperative mechanical ventilation, maximum inotropic score, and maximum vasoactive inotropic score (VIS) were independent predictors of mortality rather than patient age alone. Despite the higher initial risk, infants in Group A benefited from earlier unloading of the systemic ventricle and demonstrated less pulmonary artery (PA) distortion at follow-up. Conclusions Although BDG before age six months carries a higher early mortality risk, primarily linked to clinical severity rather than age, it can offer important advantages in systemic ventricle offloading and reduced PA distortion over time. These findings underscore the need for careful patient selection and highlight the potential for improved long-term outcomes with early BDG in appropriately selected infants.