Mortality and Heart Transplantation After Hybrid Palliation of Hypoplastic Left Heart Syndrome: A Systematic Review and Meta-Analysis

Background Newborns with hypoplastic left heart syndrome (HLHS) who are considered at increased risk for death following Norwood/Sano surgery often undergo hybrid palliation (HP) as initial surgery. We aimed to compile the HP experience in HLHS and its variants and assess the rates of, and risk factors for, death and heart transplantation.Methods CINAHL, CINAHL PLUS, PubMed/MEDLINE, and SCOPUS were systematically searched for HP outcome studies of death or heart transplantation in HLHS between 1998 and 2022. Pooled incidence was estimated, and potential risk factors were identified using random-effects meta-analysis and reconstructed time-to-event data from Kaplan-Meier curves.Results Thirty-three publications were included in our review. Overall, of 1,162 patients 417 died and 57 underwent heart transplantation, resulting in a combined outcome of 40.7%, (474/1,162). There was a trend toward decreasing mortality risk across the stages of palliation. Pooled mortality between HP and comprehensive stage 2 palliation was 25%, after stage 2 up to Fontan palliation was 16%, and 6% post-Fontan. The incidence of death or heart transplantation was higher in high-risk patients-43% died and 10% received heart transplantation.Conclusion Our systematic review and meta-analysis found high rates of death or heart transplantation in HP of HLHS patients between HP and Fontan surgeries. All patients should be closely followed during the initial interstage period, which is associated with the highest hazard. Prospective studies on appropriate patient selection, indications, and / or alternatives, as well as refining HP strategies for managing newborns with HLHS are needed to improve outcomes.