Jacquemyn X, Singh TP, Gossett JG, Averin K, Kutty S, Zühlke LJ, Abdullahi LH, Kulkarni A.World J Pediatr Congenit Heart Surg. 2024 Mar;15(2):215-223. doi: 10.1177/21501351231224323. Epub 2024 Feb 25.PMID: 38404131
Take Home Points
- This systematic review and meta-analysis found a high mortality rate in hybrid palliation of hypoplastic left heart syndrome patients, likely related to inclusion of those at highest risk.
- Mortality seems to be highest after initial palliation and decreases thereafter. Therefore, all patients should be closely followed during the initial interstage period to improve survival.
- Due to the persistent lack of substantial significant progress in hybrid palliation outcomes over an extended period, there remains a pressing need for additional research to address risk factors related to mortality following HP and to investigate alternative strategies for improving overall outcomes.
Commentary from Dr. Chun Soo Park (Seoul, Korea), section editor of Congenital Heart Surgery Journal Watch:
Summary
This study was designed to investigate the outcomes after hybrid palliation (HP) in hypoplastic left heart syndrome (HLHS) and its variants and to identify factors associated with death or transplantation. The authors systematically reviewed academic databases such as CINAHL, CINAHL PLUS, PubMed/MEDLINE, and SCOPUS to pick studies regarding the outcomes following HP in HLHS between 1998 and 2022. A total of 1162 patients from 33 publications were included in the analysis. 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. Overall, 474 events (40.7%), including 417 deaths and 57 transplants, occurred. There was a trend toward decreasing mortality risk across the stages of palliation. Pooled mortality between HP and comprehensive stage 2 palliation was 25%, 16% between stage 2 and Fontan, and 6% after Fontan. The incidence of death or heart transplantation was higher in high-risk patients; 43% died and 10% received heart transplantation. Any risk factor associated with death or transplantation was not identified.
Comments
Despite the recent advancements in understanding of the disease and in treatments, including surgery, Hypoplastic Left Heart Syndrome (HLHS) remains a challenging congenital heart disease with a consistently high risk of mortality throughout the life. There is known to be significant attrition during the interstage period, which is between the Norwood operation, the first stage palliation, and the second-stage palliation, the bidirectional Glenn procedure. This attrition is further exaggerated in patients with high-risk anatomical or baseline characteristics. The hybrid palliation (HP) strategy was introduced to improve the survival outcome of HLHS, particularly by avoiding the cardiopulmonary bypass required for the first stage palliation, the Norwood operation, in the neonatal period. Even in centers that prefer primary Norwood, the hybrid strategy has been adopted for high-risk HLHS patients to drastically improve outcomes.
The centers included in this study use HP for various purposes, making it challenging to simply evaluate its outcomes. However, the mortality or transplant rate following HP, and interstage mortality or transplant rates reaching over 25%, and the mortality or transplant exceeding 15% even after delayed performing more complex stage 2 procedures are somewhat disappointing in light of the strategy’s original goals. Nevertheless, it is encouraging to see that the outcomes have been improving recently, likely due to accumulated experience with hybrid palliation and potentially unspecified modifications over time that have driven improvement.
Future research should identify factors that could enhance hybrid palliation outcomes, which would benefit centers with limited experience or volume, where adopting a primary Norwood strategy might be daunting. Additionally, as the authors mentioned, a study—possibly a randomized controlled study—to determine the factors in which hybrid palliation might yield better results than primary Norwood, could help improve outcomes of the treatment of HLHS in centers preferring primary Norwood, which still carries a considerable mortality risk.
