Analysis of Preoperative Condition and Interstage Mortality in Norwood and Hybrid Procedures for Hypoplastic Left Heart Syndrome Using the Aristotle Scoring System

Study Questions:

What are the outcomes for patients undergoing hybrid palliations for hypoplastic left heart syndrome (HLHS) as compared with the Norwood procedure, adjusting for the fact that hybrid procedures are often done on higher-risk patients?


A retrospective review was performed at a single center. Inclusion criteria for the hybrid procedure included preoperative asphyxia, low birth weight (<2.5 kg), and restrictive interatrial septum. A modification of the comprehensive Aristotle score using 26 perioperative factors and 42 additional comorbidities was applied to each patient. Operative, interstage, and 1-year mortality were compared using Cox proportional hazard analyses.


Of a total of 138 neonates treated for HLHS during the study period, 111 underwent Norwood procedures, whereas 27 underwent hybrid procedures. The hybrid group had higher Aristotle scores (mean 4.1 vs. 1.8; p < 0.001), with no significant difference in mortality. At 1 year, the overall unadjusted survival for Norwood patients was 58.6% as compared with 51.9% for hybrid patients. The Aristotle adjusted hazard ratio for mortality for hybrid patients was 1.09 (95% confidence interval, 0.56-2.11; p = 0.8).


The authors concluded that applying a hybrid approach to high-risk patients produces comparable mortality risk to lower-risk patients undergoing the Norwood procedure.


The hybrid approach to the palliation of patients with HLHS has gained popularity in recent years, particularly for patients considered high risk for standard operative intervention. It is obviously difficult to compare outcomes between these treatment strategies because of inherent differences in baseline patient characteristics. This study attempted to account for this by use of the Aristotle scoring system. Common patient characteristics contributing to the Aristotle scores in these patients included birthweight <2.5 kg, prematurity, renal dysfunction, respiratory failure, and liver dysfunction, among others. The mortality rates in the study appear relatively high, but are not drastically different than the single-ventricle reconstruction (SVR) trial performed in North America. The 12-month survival for patients in the SVR trial was 74% for those assigned to right ventricle to pulmonary artery shunt and 64% for those assigned to the Blalock-Taussig (BT) shunt as compared with 58.6% survival in the current study, in which all patients received BT shunts. Similarly, mortality between Norwood discharge and the stage II procedure was 12.5% for Norwood patients in the current study as compared with 11.7% in the SVR trial. Hybrid palliation likely has a role in the management of neonates with HLHS. Identification of the optimal strategy will remain a challenge given heterogeneity of the patient population and evolving techniques for both conventional surgical and hybrid interventions.

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