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

Background: The “Hybrid” procedure, consisting of surgical banding of the pulmonary arteries with intraoperative stenting of the arterial duct, was developed as primary palliation in hypoplastic left heart syndrome (HLHS) avoiding the risks of cardiopulmonary bypass (CPB) and circulatory arrest. In some centers, it is reserved for low-birth-weight, premature, or unstable neonates. Its role in unselected cases of HLHS is yet to be defined.

Methods: The preoperative condition of all patients with HLHS who underwent either the hybrid or the Norwood procedure for HLHS between 2005 and 2011 was analyzed retrospectively, using a modified comprehensive Aristotle score (AS). We then compared the early (< 30 days) and interstage mortality for each cohort.

Results: Of 138 patients with HLHS, 27 had hybrid and 111 had Norwood procedures. The hybrid group had significantly higher scores (mean AS: 4.1 vs. 1.8; p < 0.001); however, there was no significant difference in the early postoperative mortality (< 30 days, 33 vs. 28%; p= 0.64) or overall interstage mortality (44 vs. 37%, p= 0.51).

Conclusions: The hybrid approach is a reasonable alternative for primary palliation of HLHS in higher risk patients, with comparable mortality to the Norwood procedure performed on a lower risk cohort. More prospective work is needed to establish whether the hybrid offers benefits over the Norwood procedure in unselected HLHS patients, and whether more complex outcomes linked to CPB, such as neurodevelopmental status, could be improved by adopting this approach.