Increased utilization of the hybrid procedure is not associated with improved early survival for newborns with hypoplastic left heart syndrome: a single-centre experience

OBJECTIVES The primary objectives were to examine utilization of the Hybrid versus the Norwood procedure for patients with hypoplastic left heart syndrome or variants and the impact on hospital mortality. The Hybrid procedure was 1st used at our institution in 2004.METHODS Review of all subjects undergoing the Norwood or Hybrid procedure between 1 January 1984 and 31 December 2022. The study period was divided into 8 eras: era 1, 1984-1988; era 2, 1989-1993; era 3, 1994-1998; era 4, 1999-2003; era 5, 2004-2008; era 6, 2009-2014; era 7, 2015-2018 and era 8, 2019-2022. The primary outcome was in-hospital mortality. Mortality rates were computed using standard binomial proportions with 95% confidence intervals. Rates across eras were compared using an ordered logistic regression model with and adjusted using the Tukey-Kramer post-hoc procedure for multiple comparisons. In the risk-modelling phase, logistic regression models were specified and tested.RESULTS The Norwood procedure was performed in 1899 subjects, and the Hybrid procedure in 82 subjects. Use of the Hybrid procedure increased in each subsequent era, reaching 30% of subjects in era 8. After adjustment for multiple risk factors, use of the Hybrid procedure was significantly and positively associated with hospital mortality.CONCLUSIONS Despite the increasing use of the Hybrid procedure, overall mortality for the entire cohort has plateaued. After adjustment for risk factors, use of the Hybrid procedure was significantly and positively associated with mortality compared to the Norwood procedure. Aortic atresia or stenosis along with mitral atresia or stenosis and hypoplasia of the left ventricle was initially described by Lev in 1952 and referred to as 'hypoplasia of the aortic tract complexes' [1].