Surgical pulmonary arterioplasty at bidirectional cavopulmonary anastomosis leads to favorable pulmonary hemodynamics at final stage palliation.

Objective: Pulmonary arterioplasty (PA plasty) at bidirectional cavopulmonary anastomosis (BDCA) is associated with increased morbidity, but outcomes to final stage palliation are unknown. We sought to determine the influence of PA plasty on pulmonary artery growth and hemodyamics at Fontan. Methods: We retrospectively reviewed clinical data and outcomes for BDCA patients from 2006 to 2018. PA plasty was categorized by extent (type 1-4), as previously described. Outcomes included pulmonary artery reintervention and mortality before final palliation. Results: Five hundred eighty-eight patients underwent BDCA. One hundred seventy-nine patients (30.0%) underwent concomitant PA plasty. Five hundred seventy (97%) patients (169 [94%] PA plasty) survived to BDCA discharge. One hundred forty out of 570 survivors (25%) required PA/Glenn reintervention before final stage palliation (59 out of 169 [35%]) PA plasty; 81 out of 401 (20%) non-PA plasty; P < .001). Twelve-, 24-, and 36-month freedom from reintervention after BDCA was 80% (95% CI, 74-86%), 75% (95% CI, 69-82%), and 64% (95% CI, 57-73%) for PA plasty, and 95% (95% CI, 93-97%), 91% (95% CI, 88-94%), and 81% (95% CI, 76-85%) for non-PA plasty (P < .001). Prefinal stage mortality was 37 (6.3%) (14 out of 169 PA plasty; 23 out of 401 non-PA plasty; P = .4). Five hundred four (144 PA plasty and 360 non-PA plasty) patients reached final stage palliation (471 Fontan, 26 1.5-ventricle, and 7 2-ventricular repair). Pre-Fontan PA pressure and pulmonary vascular resistance were 10 mm Hg (range, 9-12 mm Hg) and 1.6 mm Hg (range, 1.3-1.9 mm Hg) in PA plasty and 10 mm Hg (range, 8-12 mm Hg) and 1.5 mm Hg (range, 1.3-1.9 mm Hg) in non-PA plasty patients, respectively (P = .29, .6). Fontan hospital mortality, length of stay, and morbidity were similar. Conclusions: PA plasty at BDCA does not confer additional mortality risk leading to final palliation. Despite increased pulmonary artery reintervention, there was reliable pulmonary artery growth and favorable pulmonary hemodynamics at final stage palliation.

The Society of Thoracic Surgeons Congenital Heart Surgery Database: 2023 Update on Outcomes and Research.

The Society of Thoracic Surgeons (STS) Congenital Heart Surgery Database (CHSD) continues to be the most comprehensive database of congenital and pediatric cardiothoracic surgical procedures in the world and contains information on 664,210 operations as of June 30, 2023. The 35th harvest of the STS CHSD data was undertaken in Spring 2023, spanning the 4-year period January 1, 2019, through December 31, 2022, and included 144,919 operations performed at 114 participating sites in North America. The harvest analysis was successfully executed by the STS Research and Analytic Center. The overall unadjusted mortality rate was 2.68% and has remained stable over the 4 years included in the current harvest window. Mortality is highest in neonates (7.4%) and lowest in children (1.1%). As in prior analyses, observed mortality and postoperative length of stay in the database increase with an increase in STS-European Association for Cardio-Thoracic Surgery (STAT) Congenital Heart Surgery Mortality Categories. This quality report summarizes contemporary outcomes, provides the odds ratios for the CHSD risk model variables based on this analysis, and describes on-going efforts to improve data collection and augment analytical approaches. Lastly, 5 research publications completed in the last year using data from the CHSD are also summarized.

Morbidity and Mortality in Adult Congenital Heart Surgery: Physiologic Component Augments Risk Prediction.

BACKGROUND: We sought to evaluate whether the anatomic and physiologic stratification system (ACAP score), released as part of the American College of Cardiology/American Heart Association updated guidelines for management of adult congenital heart disease (ACHD) in 2018, better estimated mortality and morbidity after cardiac operations for ACHD. METHODS: The ACAP score was determined for 318 patients (age ≥18 years) with ACHD undergoing heart surgery at our institution between December 2001 and August 2019. The primary end point was perioperative mortality. The secondary aim was to evaluate the performance of the ACAP, The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) Congenital Heart Surgery Mortality Categories, and ACHS mortality scores/categories at predicting a composite adverse outcome of perioperative mortality, prolonged ventilation, and renal failure requiring replacement therapy. Logistic regression models were built to estimate mortality and the composite outcome using anatomic and physiologic components independently and together. Receiver operating characteristic curves were created, and area under the curves were compared using the Delong test. RESULTS: The median age was 37 years (interquartile range, 26.3-50.0 years). There were 9 perioperative mortalities (2.8%). With respect to perioperative mortality, the area under the curve using the anatomic component only was 0.74, which improved to 0.81 after including physiologic severity (P = .05). When physiologic severity was added to the model for the composite outcome, the discriminatory abilities of the ACHS mortality score and the STAT categories increased significantly to 0.83 (95% CI, 0.75-0.91; P = .02) and 0.82 (95% CI, 0.73-0.90; P = .04), comparable to the predictive power of ACAP. CONCLUSIONS: Physiologic severity augments ability to predict mortality and morbidity after cardiac surgery for ACHD. There is need for more robust ACHD-specific risk models.

Mutations in genes related to myocyte contraction and ventricular septum development in non-syndromic tetralogy of Fallot.

Objective: Eighty percent of patients with a diagnosis of tetralogy of Fallot (TOF) do not have a known genetic etiology or syndrome. We sought to identify key molecular pathways and biological processes that are enriched in non-syndromic TOF, the most common form of cyanotic congenital heart disease, rather than single driver genes to elucidate the pathogenesis of this disease. Methods: We undertook exome sequencing of 362 probands with non-syndromic TOF and their parents within the Pediatric Cardiac Genomics Consortium (PCGC). We identified rare (minor allele frequency <1 × 10-4), de novo variants to ascertain pathways and processes affected in this population to better understand TOF pathogenesis. Pathways and biological processes enriched in the PCGC TOF cohort were compared to 317 controls without heart defects (and their parents) from the Simons Foundation Autism Research Initiative (SFARI). Results: A total of 120 variants in 117 genes were identified as most likely to be deleterious, with CHD7, CLUH, UNC13C, and WASHC5 identified in two probands each. Gene ontology analyses of these variants using multiple bioinformatic tools demonstrated significant enrichment in processes including cell cycle progression, chromatin remodeling, myocyte contraction and calcium transport, and development of the ventricular septum and ventricle. There was also a significant enrichment of target genes of SOX9, which is critical in second heart field development and whose loss results in membranous ventricular septal defects related to disruption of the proximal outlet septum. None of these processes was significantly enriched in the SFARI control cohort. Conclusion: Innate molecular defects in cardiac progenitor cells and genes related to their viability and contractile function appear central to non-syndromic TOF pathogenesis. Future research utilizing our results is likely to have significant implications in stratification of TOF patients and delivery of personalized clinical care.

Recommendations for Centers Performing Pediatric Heart Surgery in the United States.

Care and outcomes for the more than 40,000 patients undergoing pediatric and congenital heart surgery in the United States annually are known to vary widely. While consensus recommendations have been published across numerous fields as one mechanism to promote a high level of care delivery across centers, it has been more than two decades since the last pediatric heart surgery recommendations were published in the United States. More recent guidance is lacking, and collaborative efforts involving the many disciplines engaged in caring for these children have not been undertaken to date. The present initiative brings together professional societies spanning numerous care domains and congenital cardiac surgeons, pediatric cardiologists, nursing, and other healthcare professionals from diverse programs around the country to develop consensus recommendations for United States centers. The focus of this initial work is on pediatric heart surgery, and it is recommended that future efforts focus in detail on the adult congenital population. We describe the background, rationale, and methodology related to this collaborative effort, and recommendations put forth for Essential Care Centers (essential services necessary for any program), and Comprehensive Care Centers (services to optimize comprehensive and high-complexity care), encompassing structure, process, and outcome metrics across 14 domains.

Recommendations for centers performing pediatric heart surgery in the United States.

Care and outcomes for the more than 40,000 patients undergoing pediatric and congenital heart surgery in the United States annually are known to vary widely. While consensus recommendations have been published across numerous fields as one mechanism to promote a high level of care delivery across centers, it has been more than two decades since the last pediatric heart surgery recommendations were published in the United States. More recent guidance is lacking, and collaborative efforts involving the many disciplines engaged in caring for these children have not been undertaken to date. The present initiative brings together professional societies spanning numerous care domains and congenital cardiac surgeons, pediatric cardiologists, nursing, and other healthcare professionals from diverse programs around the country to develop consensus recommendations for United States centers. The focus of this initial work is on pediatric heart surgery, and it is recommended that future efforts focus in detail on the adult congenital population. We describe the background, rationale, and methodology related to this collaborative effort, and recommendations put forth for Essential Care Centers (essential services necessary for any program), and Comprehensive Care Centers (services to optimize comprehensive and high-complexity care), encompassing structure, process, and outcome metrics across 14 domains.

Contemporary Relationship Between Hospital Volume and Outcomes in Congenital Heart Surgery.

BACKGROUND: Studies examining the volume-outcome relationship in congenital heart surgery (CHS) are more than a decade old. Since then, mortality has declined, and case-mix adjustment has evolved. We determined the current relationship between hospital CHS volume and outcomes. METHODS: Patients aged ≤18 years undergoing index operations in The Society of Thoracic Surgeons-Congenital Heart Surgery Database (2017-2020) were included. Associations between annual hospital volume and case-mix-adjusted operative mortality, major complications, failure to rescue (FTR), and postoperative length of stay (PLOS) were assessed using Bayesian hierarchical models, overall, by The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) category, and for the Norwood procedure. RESULTS: Across 101 centers (76,714 index operations), median annual volume was 144 operations/y. Operative mortality was 2.7%. Lower-volume hospitals had higher mortality, with an apparent transition zone at ∼190 operations/y (95% credible interval [CrI], 115-450 operations/y), below which a sustained uptick in the estimated odds of death occurred. Odds of death compared with a 450 operations/y reference were 50 operations/y (odds ratio [OR], 1.84; 95% CrI, 1.41-2.37), 100 operations/y (OR, 1.37; 95% CrI, 1.08-1.71), 200 operations/y (OR, 0.92; 95% CrI, 0.1-1.18), 300 operations/y (OR, 0.89; 95% CrI, 0.76-1.04). The volume-outcome effect was more apparent for STAT 4 to 5 than STAT 1 to 3 operations. In the overall cohort, PLOS and complications were similar across hospital volumes, whereas FTR rates were higher at lower-volume hospitals. Lower-volume hospitals had worse outcomes after the Norwood procedure, most notably mortality and FTR. CONCLUSIONS: Hospital volume is associated with mortality and FTR after CHS. The relationship is strongest for high-risk operations. These data can inform ongoing initiatives to improve CHS care.

The addition of evolocumab to maximal tolerated statin therapy improves walking performance in patients with peripheral arterial disease and intermittent claudication (Evol-PAD study).

OBJECTIVE: To test the hypothesis that in patients with peripheral arterial disease (PAD) and claudication, treated with maximal tolerated statin therapy, the addition of a monthly subcutaneous injection of evolocumab for 6 months improves treadmill walking performance. BACKGROUND: Lipid lowering therapy improves walking parameters in patients with PAD and claudication. Evolocumab decreases cardiac and limb adverse events in patients with PAD; however, the effect of evolocumab on walking performance is not known. METHODS: We performed a double-blind, randomized, placebo-controlled study to compare maximal walking time (MWT) and pain free walking time (PFWT) in patients with PAD and claudication treated with monthly subcutaneous injections of evolocumab 420 mg (n = 35) or placebo (n = 35). We also performed measurements of lower limb perfusion, brachial flow mediated dilatation (FMD), carotid intima media thickness (IMT), and serum biomarkers of PAD disease severity. RESULTS: After six-months of treatment with evolocumab MWT increased by 37.7 % (87.5 ± 24 s) compared to 1.4 % (-21.7 ± 22.9 s) in the placebo group, p = 0.01. PFWT increased by 55.3 % (67.3 ± 21.2 s) in the evolocumab group compared to 20.3 % (8.5 ± 20.3 s) in the placebo group, p = 0.051. There was no difference in lower extremity arterial perfusion measurements. FMD increased by 42.0 ± 73.9 % (1.01 ± 0.7 %) in the evolocumab group and decreased by 16.29 ± 20.06 % (0.99 ± 0.68 %) in the placebo group (p < 0.001). IMT decreased by 7.16 ± 4.6 % (0.06 ± 0.04 mm) in the evolocumab group and increased by 6.68 ± 4.9 % (0.05 ± 0.03 mm) in the placebo group, (p < 0.001). CONCLUSIONS: The addition of evolocumab to maximal tolerated statin therapy improves maximal walking time in patients with PAD and claudication, increases FMD, and decreases IMT. CONDENSED ABSTRACT: Peripheral arterial disease (PAD) impairs quality of life by causing lower extremity intermittent claudication, rest pain, or amputation. Evolocumab is a monthly injectable monoclonal antibody medication that reduces cholesterol. In this study, we randomly treated patients with PAD and claudication, and on background statin therapy, with evolocumab or placebo, and found that evolocumab improves walking performance on a treadmill test by increasing maximal walking time. We also found that evolocumab decreases plasma MRP-14 levels, a marker of PAD severity.

The Society of Thoracic Surgeons Congenital Heart Surgery Database: 2022 Update on Outcomes and Research.

The Society of Thoracic Surgeons (STS) Congenital Heart Surgery Database continues to be one of the most comprehensive clinical outcomes registries capturing almost all pediatric cardiothoracic surgical operations undertaken in the United States. The latest analysis of aggregate outcomes was performed after the 33rd data harvest and included congenital and pediatric cardiac operations performed between July 1, 2017 and June 30, 2021. This article summarizes these contemporary outcomes and provides a context for the interpretation of these outcomes. In addition this article describes ongoing efforts to improve data collection and augment analytical approaches. Finally, research activities undertaken in the last year using data from the database are also summarized.

Report of the 2022 Society of Thoracic Surgeons Congenital Heart Surgery Practice Survey.

BACKGROUND: The Society of Thoracic Surgeons Workforce on Congenital Surgery performed a practice survey to analyze contemporary data. METHODS: An electronic survey was sent to congenital heart surgeons in North America. Details on demographics, training paradigm, clinical practice, and work satisfaction were queried, tabulated, and analyzed. RESULTS: Of 312 unique contacts, 201 (64.4%) responded. Of these, 178 (89%) were practicing. The median age was 52 years (interquartile range, 43, 59 years), and 157 (88%) were male. The number of female respondents increased from 12 (7%) in 2015 to 18 (11%) at present. Practice composition was predominantly mixed pediatric and adult (141; 79%), although 15 (8%) surgeons practiced exclusively pediatric surgery. Most surgeons (154; 87%) reported performing the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery category 4 and 5 procedures. One-fourth (42; 24%) reported performing fewer than 50 pediatric cases per year, and 18 (10%) stated that their primary role was as a surgical assistant. Individual surgeon case volume was most commonly 100 to 149 total cases (29%). Although one-half (91; 51%) reported their volume as being "just right," 74 (42%) reported that their case volume was "too small." Seventy-six (43%) reported too many surgeons in their region. Of the 201 practicing surgeons, 30 (14.9%) plan retirement in the next 5 years. Most described career satisfaction, with 102 (57%) being very satisfied and 48 (27%) somewhat satisfied. CONCLUSIONS: Although most congenital heart surgeons in North America are satisfied with their careers, more than 40% believe that their caseload is inadequate and that there are too many surgeons in their region. Further analysis is warranted regarding career dissatisfaction and diversity.

Variation in Case-Mix Across Hospitals: Analysis of The Society of Thoracic Surgeons Congenital Heart Surgery Database.

BACKGROUND: The Society of Thoracic Surgeons (STS) Congenital Heart Surgery Database was queried to document variation of patient characteristics, procedure types, and programmatic case-mix. METHODS: All index cardiac operations in patients less than 18 years of age in the STS Congenital Heart Surgery Database (July 2016 to June 2020) were eligible for inclusion except patients weighing ≤2.5 kg undergoing isolated patent ductus arteriosus closure. At the hospital level, we describe variations in patient and procedural characteristics known from previous analyses to be associated with outcomes. We also report variations across hospitals of programmatic case-mix. RESULTS: Data were analyzed from 117 sites (90 322 total operations, 87 296 total index cardiac operations eligible for STAT [STS-European Association for Cardio-Thoracic Surgery] 2020 Mortality Score). The median annual total index cardiac operations eligible for STAT 2020 Mortality Score per hospital was 157 (interquartile range [IQR], 94-276). Wide variability was documented in total annual index cardiac operations eligible for STAT 2020 Mortality Score per hospital (ratio 90th/10th percentile = 9.01), operations in neonates weighing <2.5 kg (ratio 90th/10th percentile = 4.09), operations in patients with noncardiac anatomic abnormalities (ratio 90th/10th percentile = 3.46), and operations in patients with preoperative mechanical ventilation (ratio 90th/10th percentile = 3.97). At the hospital level, the median percentage of all index cardiac operations in STAT 2020 Mortality Category 5 was 3.7% (IQR, 1.7%-4.9%), the median percentage of all index cardiac operations in STAT 2020 Mortality Category 4 or 5 was 24.4% (IQR, 19.0%-28.4%), the median hospital-specific mean STAT Mortality Category was 2.39 (IQR, 2.20-2.47), and the median hospital-specific mean STAT Mortality Score was 0.86 (IQR, 0.73-0.91). CONCLUSIONS: Substantial variation of patient characteristics, procedure types, and case-mix exists across pediatric and congenital cardiac surgical programs. Knowledge about programmatic case-mix augments data about indirectly standardized programmatic observed-to-expected (O/E) mortality. Indirectly standardized O/E ratios do not provide a complete description of a given pediatric and congenital cardiac surgical program. The indirectly standardized programmatic O/E ratios associated with a given program apply only to its specific case-mix of patients and may represent a quite different case-mix than that of another program.

Ross procedure in neonates and infants: A valuable operation with defined limits.

OBJECTIVE: The Ross procedure is an important tool that offers autologous tissue repair for severe left ventricular outflow tract (LVOT) pathology. Previous reports show that risk of mortality is highest among neonates and infants. We analyzed our institutional experience within this patient cohort to identify factors that most affect clinical outcome. METHODS: A retrospective chart review identified all Ross operations in neonates and infants at our institution over 27 years. The entire study population was analyzed to determine risk factors for mortality and define outcomes for survival and reintervention. RESULTS: Fifty-eight patients underwent a Ross operation at a median age of 63 (range, 9-156) days. Eighteen (31%) were neonates. Eleven (19%) patients died before hospital discharge. Multiple regression analysis of the entire cohort identified young age (hazard ratio [HR], 1.037; P = .0045), Shone complex (HR, 17.637; P = .009), and interrupted aortic arch with ventricular septal defect (HR, 16.01; P = .031) as independent predictors of in-hospital mortality. Receiver operating characteristic analysis (area under the curve, 0.752) indicated age younger than 84 days to be the inflection point at which mortality risk increases. Of the 47 survivors, there were 2 late deaths with a mean follow-up of 6.7 (range, 2.1-13.1) years. Three patients (6%) required LVOT reintervention at 3, 8, and 17.5 years, respectively, and 26 (55%) underwent right ventricular outflow tract reintervention at a median of 6 (range, 2.5-10.3) years. CONCLUSIONS: Ross procedure is effective in children less than one year of age with left sided obstructive disease isolated to the aortic valve and/or aortic arch. Patients less than 3 months of age with Shone or IAA/VSD are at higher risk for morbidity and mortality. Survivors experience excellent intermediate-term freedom from LVOT reintervention.

Long-term outcomes with the pulmonary autograft inclusion technique in adults with bicuspid aortic valves undergoing the Ross procedure.

OBJECTIVE: To compare outcomes with wrapped (pulmonary autograft inclusion) versus unwrapped techniques in adults with bicuspid aortic valves undergoing the Ross procedure. METHODS: Between 1992 and 2019, 129 adults with bicuspid aortic valves (aged ≥18 years) underwent the Ross procedure by a single surgeon. Patients were divided into those without autograft inclusion (unwrapped, n = 71) and those with autograft inclusion (wrapped, n = 58). Median follow-up was 10.3 years (interquartile range, 3.0-16.8 years). Need for autograft reintervention was analyzed using competing risks. RESULTS: Pre- and intraoperative characteristics as well as 30-day morbidity or mortality did not differ between cohorts. Survival at 1, 5, and 10 years, respectively, was 97.2%, 97.2%, and 95.6% in the unwrapped cohort and 100%, 100%, and 100% in the wrapped cohort (P = .15). Autograft valve failure occurred in 25 (35.2%) of the unwrapped and 3 (5.2%) of the wrapped patients. Competing risks analysis demonstrated the wrapped cohort to have a lower need for autograft reintervention (subhazard ratio, 0.28, 95% confidence interval, 0.08-0.91; P = .035). The cumulative incidence of autograft reintervention (death as a competing outcome) at 1, 5, and 10 years, respectively, was 10.2%, 14.9%, and 26.8% in the unwrapped cohort and 4.0%, 4.0%, and 4.0% in the wrapped cohort. CONCLUSIONS: In adults with bicuspid aortic valves, the Ross procedure with pulmonary autograft inclusion stabilizes the aortic root preventing dilatation and reduces the need for reoperation. The autograft inclusion technique allows the Ross procedure to be performed in this population with excellent long-term outcomes.

Craniofacial and cardiac defects in chd7 zebrafish mutants mimic CHARGE syndrome.

Congenital heart defects occur in almost 80% of patients with CHARGE syndrome, a sporadically occurring disease causing craniofacial and other abnormalities due to mutations in the CHD7 gene. Animal models have been generated to mimic CHARGE syndrome; however, heart defects are not extensively described in zebrafish disease models of CHARGE using morpholino injections or genetic mutants. Here, we describe the co-occurrence of craniofacial abnormalities and heart defects in zebrafish chd7 mutants. These mutant phenotypes are enhanced in the maternal zygotic mutant background. In the chd7 mutant fish, we found shortened craniofacial cartilages and extra cartilage formation. Furthermore, the length of the ventral aorta is altered in chd7 mutants. Many CHARGE patients have aortic arch anomalies. It should be noted that the aberrant branching of the first branchial arch artery is observed for the first time in chd7 fish mutants. To understand the cellular mechanism of CHARGE syndrome, neural crest cells (NCCs), that contribute to craniofacial and cardiovascular tissues, are examined using sox10:Cre lineage tracing. In contrast to its function in cranial NCCs, we found that the cardiac NCC-derived mural cells along the ventral aorta and aortic arch arteries are not affected in chd7 mutant fish. The chd7 fish mutants we generated recapitulate some of the craniofacial and cardiovascular phenotypes found in CHARGE patients and can be used to further determine the roles of CHD7.

Clinical factors associated with microstructural connectome related brain dysmaturation in term neonates with congenital heart disease.

Objective: Term congenital heart disease (CHD) neonates display abnormalities of brain structure and maturation, which are possibly related to underlying patient factors, abnormal physiology and perioperative insults. Our primary goal was to delineate associations between clinical factors and postnatal brain microstructure in term CHD neonates using diffusion tensor imaging (DTI) magnetic resonance (MR) acquisition combined with complementary data-driven connectome and seed-based tractography quantitative analyses. Our secondary goal was to delineate associations between mild dysplastic structural brain abnormalities and connectome and seed-base tractography quantitative analyses. These mild dysplastic structural abnormalities have been derived from prior human infant CHD MR studies and neonatal mouse models of CHD that were collectively used to calculate to calculate a brain dysplasia score (BDS) that included assessment of subcortical structures including the olfactory bulb, the cerebellum and the hippocampus. Methods: Neonates undergoing cardiac surgery for CHD were prospectively recruited from two large centers. Both pre- and postoperative MR brain scans were obtained. DTI in 42 directions was segmented into 90 regions using a neonatal brain template and three weighted methods. Clinical data collection included 18 patient-specific and 9 preoperative variables associated with preoperative scan and 6 intraoperative (e.g., cardiopulmonary bypass and deep hypothermic circulatory arrest times) and 12 postoperative variables associated with postoperative scan. We compared patient specific and preoperative clinical factors to network topology and tractography alterations on a preoperative neonatal brain MRI, and intra and postoperative clinical factors to network topology alterations on postoperative neonatal brain MRI. A composite BDS was created to score abnormal findings involving the cerebellar hemispheres and vermis, supratentorial extra-axial fluid, olfactory bulbs and sulci, hippocampus, choroid plexus, corpus callosum, and brainstem. The neuroimaging outcomes of this study included (1) connectome metrics: cost (number of connections) and global/nodal efficiency (network integration); (2) seed based tractography methods of fractional anisotropy (FA), radial diffusivity, and axial diffusivity. Statistics consisted of multiple regression with false discovery rate correction (FDR) comparing the clinical risk factors and BDS (including subcortical components) as predictors/exposures and the global connectome metrics, nodal efficiency, and seed based- tractography (FA, radial diffusivity, and axial diffusivity) as neuroimaging outcome measures. Results: A total of 133 term neonates with complex CHD were prospectively enrolled and 110 had analyzable DTI. Multiple patient-specific factors including d-transposition of the great arteries (d-TGA) physiology and severity of impairment of fetal cerebral substrate delivery (i.e., how much the CHD lesion alters typical fetal circulation such that the highest oxygen and nutrient rich blood from the placenta are not directed toward the fetal brain) were predictive of preoperative reduced cost (p < 0.0073) and reduced global/nodal efficiency (p < 0.03). Cardiopulmonary bypass time predicted postoperative reduced cost (p < 0.04) and multiple postoperative factors [extracorporeal membrane oxygenation (ECMO), seizures and cardiopulmonary resuscitation (CPR)] were predictive of postoperative reduced cost and reduced global/nodal efficiency (p < 0.05). Anthropometric measurements (weight, length, and head size) predicted tractography outcomes. Total BDS was not predictive of brain network topology. However, key subcortical components of the BDS score did predict key global and nodal network topology: abnormalities of the cerebellum predicted reduced cost (p < 0.0417) and of the hippocampus predicted reduced global efficiency (p < 0.0126). All three subcortical structures predicted unique alterations of nodal efficiency (p < 0.05), including hippocampal abnormalities predicting widespread reduced nodal efficiency in all lobes of the brain, cerebellar abnormalities predicting increased prefrontal nodal efficiency, and olfactory bulb abnormalities predicting posterior parietal-occipital nodal efficiency. Conclusion: Patient-specific (d-TGA anatomy, preoperative impairment of fetal cerebral substrate delivery) and postoperative (e.g., seizures, need for ECMO, or CPR) clinical factors were most predictive of diffuse postnatal microstructural dysmaturation in term CHD neonates. Anthropometric measurements (weight, length, and head size) predicted tractography outcomes. In contrast, subcortical components (cerebellum, hippocampus, olfactory) of a structurally based BDS (derived from CHD mouse mutants), predicted more localized and regional postnatal microstructural differences. Collectively, these findings suggest that brain DTI connectome and seed-based tractography are complementary techniques which may facilitate deciphering the mechanistic relative contribution of clinical and genetic risk factors related to poor neurodevelopmental outcomes in CHD.