The Fontan Udenafil Exercise Longitudinal Trial: Subgroup Analysis.

The Pediatric Heart Network's Fontan Udenafil Exercise Longitudinal (FUEL) Trial (Mezzion Pharma Co. Ltd., NCT02741115) demonstrated improvements in some measures of exercise capacity and in the myocardial performance index following 6 months of treatment with udenafil (87.5 mg twice daily). In this post hoc analysis, we evaluate whether subgroups within the population experienced a differential effect on exercise performance in response to treatment. The effect of udenafil on exercise was evaluated within subgroups defined by baseline characteristics, including peak oxygen consumption (VO2), serum brain-type natriuretic peptide level, weight, race, gender, and ventricular morphology. Differences among subgroups were evaluated using ANCOVA modeling with fixed factors for treatment arm and subgroup and the interaction between treatment arm and subgroup. Within-subgroup analyses demonstrated trends toward quantitative improvements in peak VO2, work rate at the ventilatory anaerobic threshold (VAT), VO2 at VAT, and ventilatory efficiency (VE/VCO2) for those randomized to udenafil compared to placebo in nearly all subgroups. There was no identified differential response to udenafil based on baseline peak VO2, baseline BNP level, weight, race and ethnicity, gender, or ventricular morphology, although participants in the lowest tertile of baseline peak VO2 trended toward larger improvements. The absence of a differential response across subgroups in response to treatment with udenafil suggests that the treatment benefit may not be restricted to specific sub-populations. Further work is warranted to confirm the potential benefit of udenafil and to evaluate the long-term tolerability and safety of treatment and to determine the impact of udenafil on the development of other morbidities related to the Fontan circulation.Trial Registration NCT0274115.

Pediatric Heart Network Trial of Losartan vs. Atenolol in Children and Young Adults with Marfan Syndrome: Impact on Prescription Practices.

The Pediatric Heart Network (PHN) trial showed similar efficacy of ß-blockers (BB) and angiotensin receptor blockers (ARB) for aortic root dilation in Marfan syndrome, but the impact on prescription practices is unknown. We hypothesized BB and ARB prescriptions would increase after the trial results were published (2014). Prescription data (2007-2016) were obtained from outpatient encounters (IBM Marketscan) for Marfan syndrome patients (6 months-25 years old). Excluding 2014 as a washout period, we analyzed two intervals: 2007-2013 and 2015-2016. Medication categories included BB, ARB, angiotensin converting enzyme inhibitors (ACEI), combination (BB/ARB and/or BB/ACEI), and no drug. Interrupted time-series analysis assessed immediate level change after publication and change in slope for the trend pre- and post-publication. Odds ratios (OR) and 95% confidence intervals from logistic regressions and generalized estimating equation methods accounted for correlation of prescriptions within patients. In 1499 patients (age 14.1 ± 6.1 years, 59% female) seen 2007-2013, BB trended lower [OR 0.91 (0.89, 0.93), p < 0.001] and ARB trended higher [OR 1.12 (1.07, 1.18), p < 0.001], while combination, ACEI, and no drug remained stable. This trend persisted, but was not significant, for BB [OR 0.54 (0.27, 1.08), p = 0.37] and ARB [OR 1.91 (0.55, 6.69), p = 0.31] in 2015-2016. Combination, ACEI, and no drug remained similar. In short term follow-up, changes in prescription practices following publication of the PHN trial were not statistically significant. This may be due to a change seen prior to publication with early adoption of ARBs that was maintained after confirmation of their effectiveness.

Variation in provider compliance with sports restriction guidelines in children with an isolated bicuspid aortic valve.

BACKGROUND: Published guidelines for sports restriction for children with a bicuspid aortic valve remain controversial. We sought to describe practice variation and factors influencing sports restrictions in these children. METHODS: This retrospective single-centre study included children (7-18 years old) with an isolated bicuspid aortic valve at baseline from 1 January, 2005 to 31 December, 2014. Sports restrictions, factors potentially influencing decision-making, and outcomes were collected. Descriptive statistics and multivariable mixed-effects logistic regression models were performed with providers and patients as random effects. Provider variation was estimated using intraclass correlation coefficients. Odds ratios, 95% confidence intervals, and p-values were reported from the models. RESULTS: In 565 encounters (253 children; 34 providers), 41% recommended no sports restrictions, 40% recommended high-static and high-dynamic restrictions, and 19% had no documented recommendations. Based on published guidelines, 22% of children were inappropriately restricted while 30% were not appropriately restricted. The paediatric cardiology provider contributed to 37% of observed practice variation (p < 0.001). Sports restriction was associated with older age, males, greater ascending aorta z-score, and shorter follow-up interval. There were no aortic dissections or deaths and one cardiac intervention. CONCLUSION: Physicians frequently fail to document sports restrictions for children with a bicuspid aortic valve, and documented recommendations often conflict with published guidelines. Despite this, no adverse outcomes occurred. Providers accounted for a significant proportion of the variation in sports restrictions. Further research to provide evidence-based guidelines may improve provider compliance with activity recommendations in this population.

Left ventricular thrombus in the multisystem inflammatory syndrome in children associated with COVID-19.

A 3-year-old girl presenting with fever, mucocutaneous inflammation, and acute gastrointestinal symptoms met criteria for the multisystem inflammatory syndrome in children associated with COVID-19 (MIS-C). Echocardiography showed severely decreased left ventricular (LV) function with an apical mass. After treatment with intravenous (IV) immunoglobulin, IV steroids, anakinra, milrinone, and systemic anticoagulation, her LV function rapidly improved and the mass became increasingly mobile. Given the risk of systemic embolization, the mass was excised through left ventriculotomy and pathology confirmed a thrombus.

Transcatheter and Surgical Aortic Valve Implantation in Children, Adolescents, and Young Adults With Congenital Heart Disease.

Transcatheter aortic valve implantation (TAVI) is common in adults but rare in children and adolescents. Since 2014, our institution has incorporated a transcatheter approach as an option for aortic valve replacement in this population. The purpose of this study was to compare short-term outcomes of TAVI with surgical aortic valve replacement (SAVR). This single-center, retrospective study included patients aged 10 to 21 years who had a native SAVR or TAVI between January 2010 to April 2020. Comparative analysis of baseline characteristics and a composite outcome (stroke within 6 months, readmission within 30 days, death) between SAVR and TAVI were made using chi-square test or Wilcoxon rank sum test, as appropriate. Of the 77 patients who underwent native aortic valve implantation during the study period (60 SAVR, 17 TAVI), 46 were aged 10 to 21 years (30 SAVR, 16 TAVI). Median follow-up was 3.8 years (interquartile range 1.5 to 4.9) for the SAVR group and 1.5 years (interquartile range 1.1 to 1.2) for the TAVI group. There was no difference in the composite outcome between groups. Patients in the SAVR group were more likely to have undergone concomitant surgical intervention and have longer intensive care unit and hospital stays. In conclusion, our study suggests similar short-term outcomes between SAVR and TAVI in children and young adults aged 10 to 21 years. Longer-term studies are essential to understand the utility of TAVI and to better consider the option of a transcatheter approach as an alternative to SAVR in the pediatric population.

The impact of the American Heart Association guidelines on patients treated for incomplete Kawasaki disease.

OBJECTIVES: To compare patients treated for incomplete Kawasaki disease whose practitioners followed versus did not follow American Heart Association criteria and to evaluate the association of cardiology consultation with adherence to these guidelines. STUDY DESIGN: Single centre retrospective cohort study of patients <18 years old who received ≥1 dose of intravenous immunoglobulin for Kawasaki disease between 01/2006 and 01/2018. We collected demographics, clinical and laboratory data, coronary artery abnormalities, and cardiology consultation status. Patients treated for incomplete Kawasaki disease were divided into two groups based on adherence versus nonadherence to American Heart Association guidelines and compared by Wilcoxon rank sum test and chi-squared or Fisher's exact test. RESULTS: Of the 357 patients treated for Kawasaki disease, 109 (31%) were classified as incomplete Kawasaki disease. The American Heart Association algorithm for identifying patients with incomplete Kawasaki disease was followed in 81/109 (74%). Coronary artery abnormalities were present in 46/109 (42%) of the patients who were treated for incomplete Kawasaki disease. Cardiology consultation was more frequent in those fulfilling American Heart Association criteria for the diagnosis of incomplete Kawasaki disease versus those who did not fulfill criteria (76% versus 48%, p = 0.005). CONCLUSIONS: Over 25% of patients treated for incomplete Kawasaki disease did not meet American Heart Association guidelines. Guidelines were more frequently followed when the paediatric cardiology team was consulted. Consulting physicians with experience and expertise in the evaluation and management of incomplete KD should be strongly considered in the care of these patients.

Changes in Provider Prescribing Behavior for Infants with Single Ventricle Physiology After Evidence-Based Publications.

BACKGROUND: The impact of published evidence on clinical practice has been understudied in pediatric cardiology. OBJECTIVE: We sought to assess changes in prescribing behavior for angiotensin-converting enzyme inhibitor (ACEI) and digoxin at discharge after initial palliation of infants with single ventricle (SV) physiology following the publication of two large studies: The Pediatric Heart Network Infant Single Ventricle (PHN-ISV) trial showing no benefit with routine ACEI use and the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) analysis showing an association between digoxin and survival. METHODS: ICD-9-10 codes identified SV infants from the Pediatric Health Information System (1/2004 to 1/2018) and charge codes identified medications at discharge. Generalized estimating equations implementing segmented logistic regressions modeled medication use, before and after (with a 3-month washout period) the relevant publication (ACEI 7/1/2010; digoxin 4/1/2016). A subgroup analysis was performed for hypoplastic left heart syndrome (HLHS). RESULTS: ACEI use (37 centers, n = 4700) at discharge did not change over time during the pre-publication period. After publication of the PHN-ISV trial, ACEI use decreased (OR: 0.61, CI 0.44-0.84, p = 0.003). Digoxin use (43 centers, n = 4778) decreased by 1% monthly before publication. After the NPC-QIC publication, digoxin use increased (OR: 2.07, CI 1.05-4.08, p = 0.04) with an ongoing increase of 9% per month. Results were similar for the HLHS subgroup. CONCLUSIONS: Prescribing behavior changed congruently after the publication of evidence-based studies, with decreased ACEI use and increased digoxin use at discharge following initial palliation of SV infants. Our findings suggest scientific findings were rapidly implemented into clinical practice.

Poor Weight Recovery Between Stage 1 Palliation and Hospital Discharge for Infants with Single Ventricle Physiology: An Analysis of the National Pediatric Cardiology Quality Improvement Collaborative Phase II Dataset.

OBJECTIVE: To investigate change in weight-for-age z-scores (WAZ) and risk factors for impaired weight gain between stage 1 palliation (S1P) for single ventricle physiology and discharge. STUDY DESIGN: This was a secondary analysis of the National Pediatric Cardiology Quality Improvement Collaborative Phase II database. The primary outcome was change in WAZ between S1P and discharge. Risk factors were selected using multivariable mixed effects regression constructed by step-wise model selection, with adjustment for WAZ at S1P and a random effect for center. RESULTS: Of 730 infants who were discharged after S1P, WAZ decreased in 98.6% (-1.5 ± 0.7). WAZ at discharge was <-1 but >-2 (at risk) in 40% and <-2 (failure to thrive) in 35% of participants. Males, higher WAZ at S1P, non-S1P procedures (mostly noncardiac), increased length of stay, necrotizing enterocolitis, and angiotensin-converting enzyme inhibitor use at discharge were associated with a greater decrease in WAZ. Preoperative enteral feeding and respiratory medications were associated with a lesser decrease in the WAZ. CONCLUSIONS: Nearly all infants lose weight after S1P with little recovery by hospital discharge. At discharge, three-quarters of the infants in the cohort were at risk for impaired weight gain or had failure to thrive. Most risk factors associated with change in WAZ were unmodifiable or surrogates of disease severity. Novel interventions are needed to minimize the early catabolic effects and promote anabolic recovery after S1P.

Implications of Changing Z-Score Models for Coronary Artery Dimensions in Kawasaki Disease.

BACKGROUND: Coronary artery abnormalities in Kawasaki disease (KD) are assessed using echocardiographic z-scores. We hypothesized that changing the coronary artery (CA) z-score model would alter diagnosis and management of children with KD. METHODS: In this retrospective single-center study of children treated for KD (9/2007-1/2020), we collected echocardiographic measurements for the left anterior descending (LAD), right (RCA), and left main (LMCA) coronary arteries during 3 illness phases and calculated Boston and Pediatric Heart Network (PHN) z-scores. Agreement between Boston and PHN z-scores was assessed using Kappa (κ) and Lin's Concordance Correlation Coefficients (CCC) and Bland-Altman analysis. RESULTS: For 904 echocardiograms from 357 children, the median Boston LAD z-score was lower than the PHN (0.3 [IQR - 0.6, 1.5] vs 1.6 [IQR 0.7, 2.8], CCC 0.94 [95% CI 0.93, 0.95], moderate agreement), aggregated across all illness phases. RCA and LMCA z-scores showed substantial agreement. With conversion from Boston to PHN models, the percentage of individual LAD z-scores ≥ 2.5 increased (14.6% to 32.1%). At least one CA z-score classification changed in 213 children (59.7%) across all phases, and 48 children (13.4%) had a change that altered recommended antithrombotic strategy. Agreement between models differed by age, sex, and race. CONCLUSIONS: Conversion from Boston to PHN z-scores changed at least 1 CA z-score classification in over half of KD patients and changed recommended antithrombotic management in 13%, largely driven by LAD measurements. Since diagnosis and management of KD and KD-like diseases rely upon CA z-scores, the clinical and research implications of these findings merit further exploration.

Exercise Capacity and Predictors of Performance After Fontan: Results from the Pediatric Heart Network Fontan 3 Study.

Impaired exercise following Fontan is a surrogate of morbidity. Single-center longitudinal data exist, but there is a lack of contemporary multi-center data. Ramp cycle ergometry was re-performed in consented participants who had originally participated in the Pediatric Heart Network's Fontan cross-sectional study. Annualized change was evaluated at maximal and submaximal exercise. Associations between these outcomes and patient characteristics were analyzed. There were 336 participants in Fontan 3, mean age 23.2 years. Paired measurements of peak oxygen consumption (peak VO2) were available for 95; peak exercise data at Fontan 3 were available for 275. Percent-predicted peak VO2 declined by 0.8 ± 1.7% per year (p < 0.001). At Fontan 3, the lowest performing peak VO2 tertile had the highest rate of overweight and obesity (p < 0.001). Female gender was more prevalent in the highest performing tertile (p = 0.004). Paired data at the ventilatory anaerobic threshold (VO2 at VAT) were available for 196; VAT data at Fontan 3 were available for 311. Percent-predicted VO2 at VAT decreased by 0.8 ± 2.6% per year (p < 0.001). At Fontan 3, VO2 at VAT was better preserved than peak VO2 across all tertiles, with higher rates of overweight and obesity in the lower performing group (p = 0.001). Female gender (p < 0.001) and left ventricular morphology (p = 0.03) were associated with better performance. Submaximal exercise is better preserved than maximal in the Fontan population, but declined at the same rate over the study period. The overall longitudinal rate of decline in exercise performance is slower than what has been described previously.

The importance of expert review to clarify ambiguous situations for (Q)SAR predictions under ICH M7.

The use of in silico predictions for the assessment of bacterial mutagenicity under the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) M7 guideline is recommended when two complementary (quantitative) structure-activity relationship (Q)SAR models are used. Using two systems may increase the sensitivity and accuracy of predictions but also increases the need to review predictions, particularly in situations where results disagree. During the 4th ICH M7/QSAR Workshop held during the Joint Meeting of the 6th Asian Congress on Environmental Mutagens (ACEM) and the 48th Annual Meeting of the Japanese Environmental Mutagen Society (JEMS) 2019, speakers demonstrated their approaches to expert review using 20 compounds provided ahead of the workshop that were expected to yield ambiguous (Q)SAR results. Dr. Chris Barber presented a selection of the reviews carried out using Derek Nexus and Sarah Nexus provided by Lhasa Limited. On review of these compounds, common situations were recognised and are discussed in this paper along with standardised arguments that may be used for such scenarios in future.

Stability of Oxandrolone in Medium-Chain Triglyceride Oil and Pharmacokinetics Following Buccal Administration of the Extemporaneous Formulation in Neonates and Adults.

OBJECTIVES: Growth failure following surgical palliation of complex congenital heart defects (CHDs) is a prognosticator of poor outcomes. Many strategies for improving weight gain have been implemented in this population, with limited success. We recently described the potential of the anabolic steroid oxandrolone to improve weight gain following surgical repair of CHD when administered via a medium-chain triglyceride (MCT) oil suspension to the buccal mucosa. The current study evaluates the stability of oxandrolone in the MCT oil formulation, as well as the pharmacokinetics of oxandrolone when administered via buccal mucosa in both neonates and adults. METHODS: Stability was assessed by long-term storage of the preparation 1) at ambient conditions and 2) under photodegradative conditions for 3 days. Neonatal pharmacokinetic parameters were determined in a cohort of neonates following surgical CHD repair, whereas adult pharmacokinetics parameters were collected as part of a prospective study to evaluate the relative bioavailability of the oxandrolone in MCT oil formulation. RESULTS: We found that oxandrolone was stable in the MCT oil formulation for at least 1 month, although exposure to light hastened drug degradation. Both neonatal and adult oxandrolone pharmacokinetics were variable; however, oxandrolone in MCT oil was relatively well absorbed through the buccal mucosa (mean bioavailability = 62.5%). CONCLUSIONS: These data suggest that the variability in oxandrolone exposures is inherent to the drug, and not the formulation or route of administration. Combined, these data support further study of this novel oxandrolone in MCT oil formulation and its impact on growth following complex surgical repair of CHD in neonates.

Revisiting the bacterial mutagenicity assays: Report by a workgroup of the International Workshops on Genotoxicity Testing (IWGT).

The International Workshop on Genotoxicity Testing (IWGT) meets every four years to obtain consensus on unresolved issues associated with genotoxicity testing. At the 2017 IWGT meeting in Tokyo, four sub-groups addressed issues associated with the Organization for Economic Cooperation and Development (OECD) Test Guideline TG471, which describes the use of bacterial reverse-mutation tests. The strains sub-group analyzed test data from >10,000 chemicals, tested additional chemicals, and concluded that some strains listed in TG471 are unnecessary because they detected fewer mutagens than other strains that the guideline describes as equivalent. Thus, they concluded that a smaller panel of strains would suffice to detect most mutagens. The laboratory proficiency sub-group recommended (a) establishing strain cell banks, (b) developing bacterial growth protocols that optimize assay sensitivity, and (c) testing "proficiency compounds" to gain assay experience and establish historical positive and control databases. The sub-group on criteria for assay evaluation recommended that laboratories (a) track positive and negative control data; (b) develop acceptability criteria for positive and negative controls; (c) optimize dose-spacing and the number of analyzable doses when there is evidence of toxicity; (d) use a combination of three criteria to evaluate results: a dose-related increase in revertants, a clear increase in revertants in at least one dose relative to the concurrent negative control, and at least one dose that produced an increase in revertants above control limits established by the laboratory from historical negative controls; and (e) establish experimental designs to resolve unclear results. The in silico sub-group summarized in silico utility as a tool in genotoxicity assessment but made no specific recommendations for TG471. Thus, the workgroup identified issues that could be addressed if TG471 is revised. The companion papers (a) provide evidence-based approaches, (b) recommend priorities, and (c) give examples of clearly defined terms to support revision of TG471.

A Rare Case of Epicardial Lead Strangulation of Left Ventricular Inflow.

This is an unusual case of left atrioventricular groove strangulation by an abandoned epicardial pacing lead associated with mild left ventricular inflow obstruction, left atrial enlargement, and new atrial tachycardia that resolved with surgical lead removal. (Level of Difficulty: Intermediate.).

Are all bacterial strains required by OECD mutagenicity test guideline TG471 needed?

The International Workshop on Genotoxicity Testing (IWGT) meets every four years to seek consensus on difficult or conflicting approaches to genotoxicity testing based upon experience, available data, and analysis techniques. At the 2017 IWGT meeting in Tokyo, one working group addressed the sensitivity and selectivity of the bacterial strains specified in the Organization for Economic Cooperation and Development (OECD) Test Guideline TG471 to recommend possible modification of the test guideline. Three questions were posed: (1) Although TA100 is derived from TA1535, does TA1535 detect any mutagens that are not detected by TA100? (2) Among the options of Salmonella TA1537, TA97 or TA97a, are these strains truly equivalent? (3) Because there is a choice to use one of either E. coli WP2 uvrA, E. coli WP2 uvrA pKM101, or Salmonella TA102, are these strains truly equivalent? To answer these questions, we analyzed published bacterial mutation data in multiple strains from large (>10,000 compound) databases from Leadscope and Lhasa Limited and anonymized data for 53 compounds tested in TA1535 and TA100 provided by a pharmaceutical company. Our analysis involved (1) defining criteria for determining selective responses when using different strains; (2) identifying compounds producing selective responses based upon author calls; (3) confirming selective responses by visually examining dose-response data and considering experimental conditions; (4) using statistical methods to quantify the responses; (5) performing limited additional direct-comparison testing; and (6) determining the chemical classes producing selective responses. We found that few mutagens would fail to be detected if the test battery did not include Salmonella strains TA1535 (8/1167), TA1537 (2/247), TA102 (4/46), and E. coli WP2 uvrA (2/21). Of the mutagens detected by the full TG471 strain battery, 93% were detected using only strains TA98 and TA100; consideration of results from in vitro genotoxicity assays that detect clastogenicity increased this to 99%.

Important considerations for the validation of QSAR models for in vitro mutagenicity.

While high-level performance metrics generated from the validation of quantitative structure-activity relationship (QSAR) systems can provide valuable information on how well these models perform and where they need to be improved, they require appropriate interpretation. There is no universal performance metric which will answer all of the questions a user might ask relating to a model, and therefore, a combination of metrics should usually be considered. Furthermore, results may vary according to the chemical space being used to validate a model, and, in some cases, it may be the validation data which is lacking or ambiguous rather than the prediction being made. Finally, users also need to consider the interpretability of the predictions being made, alongside the accuracy of the predictions. In this paper, we will discuss these important considerations in more detail within the context of the results obtained at Lhasa Limited as part of the National Institute of Health Sciences (NIHS) QSAR challenge project.

Extrapolation of in vitro structural alerts for mutagenicity to the in vivo endpoint.

As part of the hazard and risk assessment of chemicals in man, it is important to assess the ability of a chemical to induce mutations in vivo. Because of the commonalities in the molecular initiating event, mutagenicity in vitro can correlate well to the in vivo endpoint for certain compound classes; however, the difficulty lies in identifying when this correlation holds true. In silico alerts for in vitro mutagenicity may therefore be used as the basis for alerts for mutagenicity in vivo where an expert assessment is carried out to establish the relevance of the correlation. Taking this into account, a data set of publicly available transgenic rodent gene mutation assay data, provided by the National Institute of Health Sciences of Japan, was processed in the expert system Derek Nexus against the in vitro mutagenicity endpoint. The resulting predictivity was expertly reviewed to assess the validity of the observed correlations in activity and mechanism of action between the two endpoints to identify suitable in vitro alerts for extension to the in vivo endpoint. In total, 20 alerts were extended to predict in vivo mutagenicity, which has significantly improved the coverage of this endpoint in Derek Nexus against the data set provided. Updating the Derek Nexus knowledge base in this way led to an increase in sensitivity for this data set against this endpoint from 9% to 66% while maintaining a good specificity of 89%.

Improvement of quantitative structure-activity relationship (QSAR) tools for predicting Ames mutagenicity: outcomes of the Ames/QSAR International Challenge Project.

The International Conference on Harmonization (ICH) M7 guideline allows the use of in silico approaches for predicting Ames mutagenicity for the initial assessment of impurities in pharmaceuticals. This is the first international guideline that addresses the use of quantitative structure-activity relationship (QSAR) models in lieu of actual toxicological studies for human health assessment. Therefore, QSAR models for Ames mutagenicity now require higher predictive power for identifying mutagenic chemicals. To increase the predictive power of QSAR models, larger experimental datasets from reliable sources are required. The Division of Genetics and Mutagenesis, National Institute of Health Sciences (DGM/NIHS) of Japan recently established a unique proprietary Ames mutagenicity database containing 12140 new chemicals that have not been previously used for developing QSAR models. The DGM/NIHS provided this Ames database to QSAR vendors to validate and improve their QSAR tools. The Ames/QSAR International Challenge Project was initiated in 2014 with 12 QSAR vendors testing 17 QSAR tools against these compounds in three phases. We now present the final results. All tools were considerably improved by participation in this project. Most tools achieved >50% sensitivity (positive prediction among all Ames positives) and predictive power (accuracy) was as high as 80%, almost equivalent to the inter-laboratory reproducibility of Ames tests. To further increase the predictive power of QSAR tools, accumulation of additional Ames test data is required as well as re-evaluation of some previous Ames test results. Indeed, some Ames-positive or Ames-negative chemicals may have previously been incorrectly classified because of methodological weakness, resulting in false-positive or false-negative predictions by QSAR tools. These incorrect data hamper prediction and are a source of noise in the development of QSAR models. It is thus essential to establish a large benchmark database consisting only of well-validated Ames test results to build more accurate QSAR models.

Information-Derived Mechanistic Hypotheses for Structural Cardiotoxicity.

Adverse events resulting from drug therapy can be a cause of drug withdrawal, reduced and or restricted clinical use, as well as a major economic burden for society. To increase the safety of new drugs, there is a need to better understand the mechanisms causing the adverse events. One way to derive new mechanistic hypotheses is by linking data on drug adverse events with the drugs' biological targets. In this study, we have used data mining techniques and mutual information statistical approaches to find associations between reported adverse events collected from the FDA Adverse Event Reporting System and assay outcomes from ToxCast, with the aim to generate mechanistic hypotheses related to structural cardiotoxicity (morphological damage to cardiomyocytes and/or loss of viability). Our workflow identified 22 adverse event-assay outcome associations. From these associations, 10 implicated targets could be substantiated with evidence from previous studies reported in the literature. For two of the identified targets, we also describe a more detailed mechanism, forming putative adverse outcome pathways associated with structural cardiotoxicity. Our study also highlights the difficulties deriving these type of associations from the very limited amount of data available.

Digoxin Use in Infants with Single Ventricle Physiology: Secondary Analysis of the Pediatric Heart Network Infant Single Ventricle Trial Public Use Dataset.

Digoxin has been associated with reduced interstage mortality after Norwood procedure. We sought to determine its association with survival and change in weight-for-age Z-score (WAZ) before the superior cavopulmonary connection (SCPC) surgery and at 14 months in a heterogeneous group of single ventricle infants. We performed a post-hoc analysis of the Pediatric Heart Network Infant Single Ventricle public use dataset to determine associations between digoxin and survival, transplant-free survival, and change in WAZ pre-SCPC and at 14 months. Sub-analyses of survival and transplant-free survival were performed for subjects who underwent Damus-Kaye-Stansel (DKS)/Norwood. Propensity score weighting was used in Cox hazard-proportion models. Of 229 subjects, 82 (36%) received digoxin and 147 (64%) received no digoxin. Pre-SCPC and 14-month survival and transplant-free survival were not significantly different between the digoxin and no digoxin groups for the main cohort and DKS/Norwood sub-group. However, in DKS/Norwood subjects there was a trend towards improved interstage transplant-free survival in the digoxin group (95.7 vs. 89.6%, p = 0.08). Digoxin was associated with a greater decrease in WAZ from birth to pre-SCPC (- 1.96 ± 0.19 vs. - 1.31 ± 0.18, p < 0.001) and birth to 14 months (- 0.64 ± 0.15 vs. - 0.19 ± 0.15, p = 0.03). Digoxin was not associated with improved survival during the interstage or at 14 months in a mixed single ventricle cohort, but there was a trend towards improved interstage transplant-free survival in post-Norwood infants. As digoxin was associated with poorer weight gain, further research is needed to identify the risks/benefits for anatomic subtypes of infants with single ventricles.