Is a hybrid strategy a lower-risk alternative to stage 1 Norwood operation?
For neonates with critical left ventricular outflow tract obstruction (LVOTO), hybrid procedures are an alternative to the Norwood stage 1 procedure. Despite perceived advantages, however, outcomes are not well defined. Therefore, we compared outcomes after stage 1 hybrid and Norwood procedures.



In a critical LVOTO inception cohort (2005-2014; 20 institutions), a total of 564 neonates underwent stage 1 palliation with the Norwood operation with a modified Blalock-Taussig shunt (NW-BT; n = 232; 41%), Norwood operation with a right ventricle-to-pulmonary artery conduit (NW-RVPA; n = 222; 39%), or a hybrid procedure (n = 110; 20%). Post-stage 1 outcomes were analyzed via competing-risks and parametric hazard analyses and compared among all 564 patients and between patients who underwent propensity-matched hybrid and those who underwent NW-BT/NW-RVPA.



By 6 years after the stage 1 operation, 50% ± 3%, 7% ± 2%, and 4% ± 1% of patients transitioned to Fontan, transplantation, and biventricular repair, respectively, whereas 7% ± 2% were alive without transition and 32% ± 2% died. Risk factors for death without transition included procedure type, smaller ascending aorta, aortic valve atresia, and lower birth weight. Risk-adjusted 4-year survival was better after NW-RVPA than after NW-BT or hybrid (76% vs 60% vs 61%; P < .001). Furthermore, for neonates with lower birth weight (<∼2 kg), an interaction between birth weight and hybrid resulted in a trend toward better survival after hybrid compared with NW-BT or NW-RVPA. For propensity-matched neonates between hybrid and NW-BT (88 pairs), 4-year survival was similar (62% vs 57%; P = .58). For propensity-matched neonates between hybrid and NW-RVPA (81 pairs), 4-year survival was better after NW-RVPA (59% vs 75%; P = .008).



For neonates with critical LVOTO undergoing single-ventricle palliation, NW-RVPA was associated with the best overall survival. Hybrid strategies are not a lower-risk alternative to Norwood operations overall; however, the impact of lower birth weight on survival may be mitigated after hybrid procedures compared with Norwood operations.
Congenital Heart Surgeons' Society Data Center, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada.
Travis J
TJ
Wilder
Division of Pediatric Cardiology, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: brian.mccrindle@sickkids.ca.
Brian W
BW
McCrindle
Department of Cardiovascular Surgery, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada.
Edward J
EJ
Hickey
Division of Cardiac and Thoracic Surgery, Department of Surgery, University of Chicago Medicine, Chicago, Ill.
Gerhard
G
Ziemer
Department of Cardiothoracic Surgery, Montreal Children's Hospital of the McGill University Health Center, Montreal, Quebec, Canada.
Christo I
CI
Tchervenkov
Department of Surgery, Johns Hopkins School of Medicine, Baltimore, Md.
Marshall L
ML
Jacobs
Division of Cardiothoracic Surgery, Department of Surgery, University of Iowa Carver College of Medicine, Iowa City, Iowa.
Peter J
PJ
Gruber
Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
Eugene H
EH
Blackstone
Congenital Heart Surgeons' Society Data Center, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada.
William G
WG
Williams
Department of Cardiothoracic Surgery, Arnold Palmer Hospital for Children, Orlando, Fla.
William M
WM
DeCampli
Department of Cardiovascular Surgery, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada.
Christopher A
CA
Caldarone
Nemours Cardiac Center, Alfred I. DuPont Hospital for Children, Wilmington, Del.
Christian
C
Pizarro
D000367:Age Factors; D001724:Birth Weight; D058366:Blalock-Taussig Procedure / Q000009:adverse effects / Q000401:mortality; D002170:Canada; D005260:Female; D018729:Fontan Procedure; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D016027:Heart Transplantation; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D058327:Norwood Procedures / Q000009:adverse effects / Q000401:mortality; D010166:Palliative Care; D011446:Prospective Studies; D020127:Recovery of Function; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*
Norwood; congenital heart disease; critical left ventricular outflow tract obstruction; hybrid; hypoplastic left heart syndrome; single ventricle