Volume-Outcome Relationship of Norwood Procedures: Insights from the National Pediatric Cardiology - Quality Improvement Collaborative Database

BACKGROUND: Prior investigations of the center-specific case volume on outcomes in hypoplastic left heart syndrome have conflicting results. This study utilized the National Pediatric Cardiology-Quality Improvement Collaborative registry to investigate the center volume-outcome relationship in patients after the Norwood procedure with consideration of preoperative high-risk features.

METHODS: Between 2016 and 2023, centers were categorized by Norwood procedure volume into low- (≤5 cases/y), medium- (6 to 10 cases/y), and high-volume centers (>10 cases/y). We compared preoperative high-risk features between the center volume categories and assessed survival outcomes, focusing on 30-day and 1-year mortality. We further compared short-term perioperative morbidity outcomes.

RESULTS: We analyzed 3397 patients from 69 institutions participating in the National Pediatric Cardiology-Quality Improvement Collaborative. Twenty-nine centers were classified as a low-, 20 as medium-, and 20 as high-volume centers. There was no difference in frequency of preoperative high-risk features among the center categories in the majority of considered variables. There was no association between the volume categories and 30-day mortality. Low-volume and medium-volume were associated with higher risk of 1-year mortality. This difference remained when adjusting for the presence of high-risk features (Low: odds ratio, 1.40 [95% CI, 1.03-1.60], P = .020; Medium: odds ratio, 1.28 [95% CI, 1.05-1.86], P = .025). Postoperative comorbidities were more frequent in low- and medium-volume centers, including the need for diagnostic and interventional catheterization.

CONCLUSIONS: Patients undergoing Norwood procedure in low- and medium-volume centers have worse 1-year mortality. The outcome characteristics are potentiated when adjusted for high-risk features, with significantly higher survival and lower morbidity in patients treated in high-volume centers.