Identification of cell-free DNA methylation patterns unique to the human left ventricle as a potential indicator of acute cellular rejection.

Increased levels of donor-derived cell-free DNA (dd-cfDNA) in recipient plasma have been associated with rejection after transplantation. DNA sequence differences have been used to distinguish between donor and recipient, but epigenetic differences could also potentially identify dd-cfDNA. This pilot study aimed to identify ventricle-specific differentially methylated regions of DNA (DMRs) that could be detected in cfDNA. We identified 24 ventricle-specific DMRs and chose two for further study, one on chromosome 9 and one on chromosome 12. The specificity of both DMRs for the left ventricle was confirmed using genomic DNA from multiple human tissues. Serial matched samples of myocardium (n = 33) and plasma (n = 24) were collected from stable adult heart transplant recipients undergoing routine endomyocardial biopsy for rejection surveillance. Plasma DMR levels increased with biopsy-proven rejection grade for individual patients. Mean cellular apoptosis in biopsy samples increased significantly with rejection severity (2.4%, 4.4% and 10.0% for ACR 0R, 1R, and 2R, respectively) but did not show a consistent relationship with DMR levels. We identified multiple DNA methylation patterns unique to the human ventricle and conclude that epigenetic differences in cfDNA populations represent a promising alternative strategy for the non-invasive detection of rejection.

Determination of peak cardiorespiratory fitness parameters in children: which averaging method should we use?

The purpose of this study was to identify which averaging methods most accurately measures peak cardiorespiratory fitness (CRF) parameters [peak O2 uptake (VO2), peak O2pulse and peak respiratory exchange ratio (RER)] in a sample of healthy children and adolescents. In this cross-sectional multicenter study, we recruited 278 healthy children aged 12-17 years. We compared the mean peak value of three CRF parameters using the recommended averaging methods (30-second block average) with alternative averaging methods such as moving averages or shorter smoothing periods. We also assessed averaging methods for accuracy by individually reviewing breath-by-breath scatter plots. The 30-second block average method resulted in a lower mean peak VO2 and in an increased proportion of underestimated peak values. Using a 30-second moving average significantly increased mean peak values which increased accuracy. Similar results were found for peak RER and peak O2pulse. In conclusion, the currently recommended averaging method (30-second block average) increased the risk of misinterpretation of peak CRF values in children. Using a moving average approach decreased misinterpretation and increased accuracy.

Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent.

An alternative method for forming sulfonates through hypervalent iodine(III) reagent-mediated oxidation of sodium sulfinates has been developed. This transformation involves trapping reactive sulfonium species using alcohols. With additional optimization of the reaction conditions, the method appears extendable to other nucleophiles such as electron-rich aromatic systems or cyclic ethers through a ring opening pathway.

A Systematic Review of Reference Values in Pediatric Cardiopulmonary Exercise Testing.

Cardiopulmonary exercise testing (CPET) is used for the diagnosis and prognosis of cardiovascular and pulmonary conditions in children and adolescents. Several authors have published reference values for pediatric CPET, but evaluation of their validity is lacking. The aim of this study was to review pediatric CPET references values published between 1980 and 2014. We specifically assessed the adequacy of the normalization methods used to adjust for body size. Articles that proposed references values were reviewed. We abstracted information on exercise protocols, CPET measurements and normalization methods. We then evaluated the studies' methodological quality and assessed them for potential biases. Thirty-four studies were included. We found important heterogeneity in the choice of exercise protocols and in the approach to adjustment for body size or other relevant confounding factors. Adjustment for body size was principally done using linear regression for age or weight. Assessment of potential biases (residual association, heteroscedasticity and departure from the normal distribution) was mentioned in only a minority of studies. Our study shows that contemporary pediatric reference values for CPET have been developed based on heterogeneous exercise protocols and variable normalization strategies. Furthermore, assessment of potential bias has been inconsistent and insufficiently described. High-quality reference values with adequate adjustment for confounding variables are needed in order to optimize CPET's specificity and sensitivity to detect abnormal cardiopulmonary response to exercise.

Determinants and Clinical Outcomes of Patients With Tetralogy of Fallot Lost to Cardiology Follow-up.

BACKGROUND: Various rates of loss to follow-up (LTFU) have been reported in patients with congenital heart disease, but return to follow-up is rarely considered in those analyses. Outcomes of LTFU patients are difficult to assess because the patients no longer attend cardiac care. We leveraged data from the TRIVIA cohort, which combines more than 30 years of clinical and administrative data, allowing us to study outcomes even after LTFU. METHODS: This population-based cohort included 904 patients with tetralogy of Fallot (TOF) born from 1982 to 2015 in Québec, Canada. Risk factors for LTFU and outcomes were calculated by Cox models and marginal means/rates models. Outcomes of LTFU patients were compared with propensity score-matched non-LTFU patients. RESULTS: The cumulative risk of experiencing 1 episode of LTFU was 50.3% at 30 years. However, return to follow-up was frequent and the proportion of patients actively followed was 85.9% at 10 years, 76.4% at 20 years, and 70.6% at 30 years. Factors associated with a reduced risk of LTFU were primary repair with conduit (hazard ratio [HR] 0.29, 95% confidence interval [CI] 0.15-0.58) and transannular patch (HR 0.60, 95% CI 0.46-0.79). LTFU patients had lower rates of cardiac hospitalisations (HR 0.49, 95% CI 0.42-0.56) and cardiac interventions (HR 0.32, 95% CI 0.25-0.42), but similar rates of cardiac mortality (HR 0.95, 95% CI 0.24-3.80). CONCLUSIONS: There was a lower proportion of LTFU patients compared with previous studies. Factors associated with lower rates of LTFU were conduits and non-valve-sparing surgery. LTFU patients had lower rates of cardiac procedures and cardiac hospitalisations.

Outcomes After Pediatric Pulmonary Valve Replacement in Patients With Tetralogy of Fallot.

BACKGROUND: People with tetralogy of Fallot might require a transannular patch during primary repair, which leads to pulmonary valve regurgitation. Pulmonary valve replacement (PVR) is performed to prevent complications of chronic pulmonary regurgitation, but the optimal timing of PVR remains a matter of debate. In this study we aimed to assess the association of PVR performed in children younger than 18 years of age with the rate of hospitalizations, interventions, and mortality. METHODS: This was a retrospective observational cohort of people with tetralogy of Fallot born in Québec between 1982 and 2015, using a combination of clinical and administrative data. Marginal means and rates models and survival curves were used to compare outcomes of patients with pediatric PVR (younger than 18 years) and those without. Outcomes of interest were rates of cardiac hospitalizations, all-cause hospitalizations, cardiac interventions, and mortality. Groups were balanced using models weighed on the inverse probability of receiving pediatric PVR. RESULTS: Of the 316 eligible patients, 58 (18.4%) received a pediatric PVR. Compared with patients who did not receive pediatric PVR, they were at increased risk of cardiac hospitalizations, although the rates of cardiac hospitalization were low: 0.50 vs 0.09 hospitalizations per 20 years (hazard ratio [HR] = 4.71 [95% confidence interval (CI), 2.22-9.96]). Patients who received a pediatric PVR had a comparable risk of all-cause hospitalizations (HR = 0.95 [95% CI, 0.71-1.26]) and of cardiac interventions (HR = 1.13 [95% CI, 0.72-1.77]). CONCLUSIONS: Patients who underwent pediatric PVR had higher rates of cardiac hospitalizations, but similar rates of all-cause hospitalizations, cardiac procedures, and mortality. In this observational cohort, pediatric PVR was not associated with an improved outcome.

Patient-Reported Outcomes After Tetralogy of Fallot Repair.

BACKGROUND: Comprehensive assessment of tetralogy of Fallot (TOF) outcomes extends beyond morbidity and mortality to incorporate patient-reported outcomes (PROs), including quality of life (QOL) and health status (HS). OBJECTIVES: This study explored PROs in adolescents and adults with TOF and delineated variables associated with PROs. METHODS: This was a cross-sectional observational study within a larger prospective registry of adolescents and adults with repaired TOF and moderate or greater pulmonary regurgitation from North America, Europe, and Asia. Participants completed PROs, including a QOL linear analogue scale (QOL-LAS) and an HS visual analogue scale (HS-VAS). Scores were classified according to age cohorts: <18, 18 to 25, 26 to 40, and >40 years. RESULTS: The study included 607 patients (46.3% female; median age 28.5 years). Median QOL-LAS scores (0-100) were similar across age cohorts (85, 80, 80, 80; P = 0.056). Median HS-VAS scores (0-100) were lowest for the oldest cohort (77) compared with the 3 younger cohorts (85, 80, 80) (P = 0.004). With advancing age, there were increased reports of poor mobility (P < 0.001) and pain or discomfort (P = 0.004); problems in these dimensions were reported by 19.1% and 37.2% of patients aged >40 years, respectively. Of factors associated with superior PROs on multivariable regression modeling (ie, being White, being nonsyndromic, having employment, and having better left ventricular function; P < 0.05), asymptomatic status (functional class I) was the variable associated with the greatest number of QOL and HS measures (P < 0.001). CONCLUSIONS: Strategies to improve TOF outcomes should consider PROs alongside conventional clinical variables. Factors associated with poorer PROs represent opportunities to intervene to improve the lives of patients with TOF.

Comparison of Long-term Outcomes of Valve-Sparing and Transannular Patch Procedures for Correction of Tetralogy of Fallot.

Importance: The choice of the right surgical technique for correction of tetralogy of Fallot (TOF) is contentious for patients with a moderate to severe right outflow tract obstruction. The use of a transannular patch (TAP) exposes patients to chronic pulmonary regurgitation, while valve-sparing (VS) procedures may incompletely relieve pulmonary obstruction. Objective: To compare 30-year outcomes of TOF repair after a VS procedure vs TAP. Design, Setting, and Participants: This retrospective population-based cohort study was conducted among all patients with TOF born in the province of Quebec, Canada, from 1980 to 2015 who underwent complete surgical repair. Patients who received a TAP or VS procedure were matched using a propensity score based on preoperative factors in a 1:1 ratio. Data were analyzed from March 2020 through April 2021. Exposures: The study groups were individuals who received TAP and those who received VS. The VS group was further stratified by the presence of residual pulmonary stenosis. Main Outcomes and Measures: The primary outcome was all-cause mortality, with 30-year survival evaluated using Cox proportional-hazards models. Secondary outcomes included the cumulative mean number of cardiovascular interventions, pulmonary valve replacements (PVRs), and cardiovascular hospitalizations were evaluated using marginal means/rates regressions. Results: Among 683 patients with TOF (401 patients who underwent TAP [58.7%] and 282 patients who underwent a VS procedure [41.3%]), adequate propensity score matching was achieved for 528 patients (264 patients who underwent a VS procedure and 264 patients who underwent TAP). Among this study cohort, 307 individuals (58.1%) were men. The median (interquartile range [IQR]) follow-up was 16.0 (8.1-25.4) years, for a total of 8881 patient-years, including 63 individuals (11.9%) followed up for more than 30 years. Individuals who received a VS procedure had an increased 30-year survival of 99.1% compared with 90.4% for individuals who received TAP (hazard ratio [HR], 0.09 [95% CI, 0.02-0.41]; P = .002). Patients who underwent TAP had an increased 30-year cumulative mean number of cardiovascular interventions compared with patients who underwent a VS procedure without residual pulmonary stenosis (2.0 interventions [95% CI, 1.5-2.7 interventions] vs 0.7 interventions [95% CI, 0.5-1.1 interventions]; mean ratio [MR], 0.36 [95% CI, 0.25-0.50]; P < .001) and patients who underwent a VS procedure with at least moderate residual stenosis (1.3 interventions [95% CI, 0.9-1.9 interventions]; MR, 0.65 [0.45-0.93]; P = .02). Results were similar for PVR, with a 30-year cumulative mean 0.3 PVRs [95% CI, 0.1-0.7 PVRs] for patients who underwent a VS procedure without residual pulmonary stenosis (MR, 0.22 [95% CI, 0.12-0.43]; P < .001) and 0.6 PVRs (95% CI, 0.2-1.5 PVRs) for patients with at least moderate residual stenosis (MR, 0.44 [95% CI, 0.21-0.93]; P = .03), compared with 1.4 PVRs (95% CI, 0.8-2.5 PVRs) for the TAP group. No statistically significant difference was found for cardiovascular hospitalizations. Conclusions and Relevance: This study found that patients who underwent a VS procedure had increased 30-year survival, fewer cardiovascular reinterventions, and fewer PVRs compared with individuals who underwent TAP, even in the presence of significant residual pulmonary stenosis. These findings suggest that it is beneficial to perform a VS procedure when possible, even in the presence of moderate residual stenosis, compared with the insertion of a TAP.

The 30-Year Outcomes of Tetralogy of Fallot According to Native Anatomy and Genetic Conditions.

BACKGROUND: The reported survival of tetralogy of Fallot (TOF) is > 97%. Patients with pulmonary atresia and/or genetic conditions have worse outcomes, but long-term estimates of survival and morbidity for these TOF subgroups are scarce. The objective of this study was to describe the 30-year outcomes of TOF according to native anatomy and the coexistence of genetic conditions. METHODS: The TRIVIA (Tetralogy of Fallot Research for Improvement of Valve Replacement Intervention: A Bridge Across the Knowledge Gap) study is a retrospective population-based cohort including all TOF subjects born from 1980 to 2015 in Québec. We evaluated all-cause mortality by means of Cox proportional hazards regression, and cumulative mean number of cardiovascular interventions and unplanned hospitalisations with the use of marginal means/rates models. We computed 30-year estimates of outcomes according to TOF types, ie, classic TOF (cTOF) and TOF with pulmonary atresia (TOF-PA), and the presence of genetic conditions. RESULTS: We included 960 subjects. The median follow-up was 17 years (interquartile range, 8-27). Nonsyndromic cTOF subjects had a 30-year survival of 95% and had undergone a mean of 2.8 interventions and 0.5 hospitalisations per subject. In comparison, TOF-PA subjects had a lower 30-year survival of 78% and underwent a mean of 8.1 interventions, with 4 times as many hospitalisations. The presence of a genetic condition was associated with lower survival (< 85% for cTOF and < 60% for TOF-PA) but similar numbers of interventions and hospitalisations. CONCLUSIONS: The anatomic types and the presence of genetic conditions strongly influence the long-term outcomes of TOF. We provided robust 30-year estimates for key markers of prognosis that may be used to improve risk stratification and provide more informed counselling to families.

Novel Z Scores to Correct Biases Due to Ventricular Volume Indexing to Body Surface Area in Adolescents and Young Adults.

BACKGROUND: Reference values for cardiac magnetic resonance imaging (cMRI) in children and young adults are scarce. This leads to risk stratification of patients with congenital heart diseases being based on volumes indexed to body surface area (BSA). We aimed to produce cMRI Z score equations for ventricular volumes in children and young adults and to test whether indexing to BSA resulted in an incorrect assessment of ventricular dilation according to sex, body composition, and growth. METHODS: We retrospectively included 372 subjects aged < 26 years with either normal hearts or conditions with no impact on ventricular volumes (reference group), and 205 subjects with repaired tetralogy of Fallot (TOF) aged < 26 years. We generated Z score equations by means of multivariable regression modelling. Right ventricular dilation was assessed with the use of Z scores and compared with indexing to BSA in TOF subjects. RESULTS: Ventricular volume Z scores were independent from age, sex, and anthropometric measurements, although volumes indexed to BSA showed significant residual association with sex and body size. In TOF subjects, indexing overestimated dilation in growing children and underestimated dilation in female compared with male subjects, and in overweight compared with lean subjects. CONCLUSIONS: Indexed ventricular volumes measured with cMRI did not completely adjust for body size and resulted in a differential error in the assessment of ventricular dilation according to sex and body size. Our proposed Z score equations solved this problem. Future studies should evaluate if ventricular volumes expressed as Z scores have a better prognostic value than volumes indexed to BSA.

Is It Worth It? A Comparison of an Intensive Interdisciplinary Pain Treatment and a Multimodal Treatment for Youths With Pain-related Disability.

OBJECTIVE: The objective of this study was to evaluate the effectiveness of an intensive interdisciplinary pain treatment (IIPT) day-hospital program as compared with an outpatient multimodal treatment (MMT) for youth with chronic pain. MATERIALS AND METHODS: A nonrandomized pretest posttest with control group design was used. A battery of patient-oriented measures assessing pain interference, quality of life, and depressive symptoms were completed at treatment commencement and at 3, 6, and 12 months after treatment by 44 youths enrolled in the IIPT and 138 youths engaged in the MMT, with various chronic pain conditions. Data were analyzed using longitudinal mixed-effects models. RESULTS: The main outcomes were the score difference from baseline of patient-oriented measures across 3 timepoints within 12 months of intervention initiation for both treatment groups. IIPT participants demonstrated greater improvement in pain interference, as compared with MMT at 3 and 12 months. Initially, health-related quality of life scores improved similarly in both groups, but greater improvement was seen in the MMT group at 12 months. Depressive symptom scores did not improve with either intervention. Only pain interference scores reached statistically and clinically significant difference levels. DISCUSSION: This study supports the benefits of specialized rehabilitation interventions, including both MMT and IIPT programs, for youths with chronic pain. The findings also suggest that IIPT might have a greater long-term effect for helping youths, in particular those with high pain interference scores.

The TRIVIA Cohort for Surgical Management of Tetralogy of Fallot: Merging Population and Clinical Data for Real-World Scientific Evidence.

BACKGROUND: Guidelines for surgical management of tetralogy of Fallot (TOF) are often based on low-quality evidence due to the many challenges of congenital heart disease: heterogeneous cardiac anatomy, consequences from surgical interventions arising years later, and scarcity of hard outcomes. The overarching goal of the Tetralogy of Fallot Research for Improvement of Valve replacement Intervention: A Bridge Across the Knowledge Gap (TRIVIA) study is to evaluate the long-term impact of the surgical management strategies in TOF. The specific objectives are: (1) to describe the long-term outcomes of TOF according to the native anatomy and the presence of genetic conditions, (2) to evaluate the long-term outcomes of surgical repair according to associated residual lesions, and (3) to evaluate the impact of paediatric pulmonary valve replacements on the long-term outcomes. METHODS: The TRIVIA study is a population-based cohort including all subjects with TOF in the province of Québec between 1980 and 2017. It links patient-level granular clinical data with long-term administrative health care data. We will evaluate mortality, cardiovascular interventions, and hospitalizations for adverse cardiovascular events using survival Cox models and marginal mean/rates models for recurrent events, respectively. Multivariate multilevel models will correct for potential confounders, and risk score matching will mitigate the potential of confounding by indication. RESULTS: The current TRIVIA cohort includes 1001 eligible subjects with TOF with complete lifelong follow-up for > 98%. The median follow-up is 17.1 years, totalling > 17,000 patient-years. CONCLUSIONS: Universal health insurance data combined with granular clinical data enable the development of population-based cohorts, to which contemporary statistical methods are applied to address important research questions in congenital heart disease research.

CONTEXTE: Les lignes directrices pour la prise en charge chirurgicale de la tétralogie de Fallot (TdF) sont souvent basées sur des données de faible qualité en raison des nombreux défis posés par les maladies cardiaques congénitales : anatomie cardiaque hétérogène, répercussions des interventions chirurgicales survenant des années plus tard et rareté de conclusions solides. L'objectif principal de l'étude TRIVIA ( T etralogy of Fallot R esearch for I mprovement of V alve replacement I ntervention: A Bridge Across the Knowledge Gap) est d'évaluer l'impact à long terme des stratégies de prise en charge chirurgicale dans les TdF. Les objectifs spécifiques sont les suivants : (1) décrire les issues à long terme de la TdF en fonction de l'anatomie native et de la présence de conditions génétiques, (2) évaluer les conséquences à long terme de la chirurgie réparatrice en fonction des lésions résiduelles associées, et (3) évaluer l'impact des remplacements valvulaires pulmonaires pédiatriques sur le pronostic à long terme. MÉTHODES: L'étude TRIVIA est une étude de cohorte basée sur une population comprenant tous les sujets atteints de TdF dans la province du Québec entre 1980 et 2017. Elle fait le lien entre les données cliniques détaillées des patients et les données administratives des soins de santé à long terme. Nous évaluerons la mortalité, les interventions cardiovasculaires et les hospitalisations pour troubles cardiovasculaires en utilisant respectivement des analyses de survie par les modèles de Cox et des modèles de moyennes/taux marginaux pour les événements récurrents. Des modèles multivariés à plusieurs niveaux permettront de corriger les facteurs de confusion potentiels, et l'appariement par des scores de risque atténuera le potentiel de confusion par indication. RÉSULTATS: La cohorte de l'étude TRIVIA comprend actuellement 1001 sujets admissibles atteints de TdF avec un suivi complet tout au long de la vie pour > 98 %. Le suivi médian est de 17,1 ans, pour un total de > 17 000 patients-années. CONCLUSIONS: Les données de l'assurance maladie universelle combinées à des données cliniques détaillées permettent la mise en place de cohortes populationnelles, auxquelles les méthodes statistiques contemporaines pourront être appliquées afin de répondre aux questions importantes pour la recherche portant sur les maladies cardiaques congénitales.

Long-Term Risk Factors for Dilatation of the Proximal Aorta in a Large Cohort of Children With Bicuspid Aortic Valve.

BACKGROUND: Patients with bicuspid aortic valve (BAV) have a higher risk of developing aortic valve dysfunction and progressive proximal aorta dilatation, which can lead to aortic dissection. To this day, identification of children at risk of developing severe aortic dilatation during their pediatric follow-up is still challenging because most studies were restricted to adult subjects. The overarching goal of this study was to identify risk factors of aortic dilatation in children with BAV. METHODS: We extracted clinical and echocardiographic data of all BAV subjects aged 0 to 20 years followed at Centre Hospitalier Universitaire Sainte-Justine between 1999 and 2016. We excluded subjects with concomitant heart defects and conditions affecting proximal aorta dimensions. Proximal aorta diameters (expressed as Z scores) were modeled in relation to age and potential predictive variables in a linear mixed model. The primary outcome was the rate of dilatation. RESULTS: We included 761 subjects (3134 echocardiograms) in final analyses. The mean ascending aorta Z score progression rate for BAV patient with a normally functioning aortic valve was estimated at 0.05 Z score unit per year. The strongest predictors of an increased dilatation rate were severe aortic stenosis, moderate and severe aortic regurgitation, and uncorrected coarctation of the aorta. Aortic valve leaflet fusion pattern and sex were not associated with progression rate. CONCLUSIONS: Children with a normally functioning BAV exhibited a very slow proximal aorta dilatation rate. Ascending aorta dilatation rate was significantly increased in patients with more than mild aortic valve dysfunction but was independent from BAV leaflet fusion type.

Effect of gestational diabetes and insulin resistance on offspring's myocardial relaxation kinetics at three years of age.

PURPOSE: Scientific evidence on the long-term impact of gestational diabetes mellitus (GDM) on offspring's myocardial relaxation is scarce. Studies have linked GDM with transient ventricular hypertrophy in newborns resulting in diastolic dysfunction, but long-term assessment is lacking. The main objective of this study was to evaluate myocardial relaxation in 3-year-old children in relation to the degree of insulin resistance of their mother during pregnancy. METHODS: We prospectively assessed myocardial relaxation by echocardiography imaging on 106 children at 3 years of age. Subjects were divided into 3 groups [GDM, insulin resistance (IR) and normoglycemic (CTRL)], based on their mother's 75g-OGTT and HOMA-IR results at second trimester screening. We collected information on children adiposity and body size, maternal characteristics and maternal and cord blood measurement of C-peptide and insulin. RESULTS: The study population comprised 29 children from GDM mothers, 36 children from IR mothers and 41 CTRL children. Compared to the CTRL group, we found that a higher proportion of children in the IR group and the GDM group met the criteria for impaired myocardial relaxation, but this did not reach statistical significance (odds ratio adjusted for heart rate and body surface area of 1.4 [0.2-9.5] and 3.5 [0.6-20.6], respectively). CONCLUSION: We did not detect an increased risk of impaired myocardial relaxation at three years of age in children exposed in-utero to IR and GDM, compared to children from normoglycemic mothers.

New Reference Values for Cardiopulmonary Exercise Testing in Children.

INTRODUCTION: Cardiopulmonary exercise testing is an essential tool to assess cardiorespiratory fitness (CRF) in children. There is a paucity of adequate pediatric reference values that are independent of body size and pubertal stage. The purpose of this study is to provide Z score equations for several maximal and submaximal CRF parameters derived from a prospectively recruited sample of healthy children. METHODS: In this cross-sectional multicenter study, we prospectively recruited 228 healthy children 12 to 17 yr old in local schools. We performed a symptom-limited cardiopulmonary exercise testing progressive ramp protocol on an electronically braked cycle ergometer. Eighteen CRF parameters were analyzed. We tested several regression models to obtain prediction curves that minimized residual association with age, body size, and pubertal stage. Both the predicted mean and the predicted SD were modeled to account for heteroscedasticity. RESULTS: We identified nonlinear association of CRF parameters with body size and significant heteroscedasticity. To normalize CRF parameters, the use of a single body size variable was not sufficient. We therefore used multivariable models with various combination of height, corrected body mass, and age. Final prediction models yielded adjusted CRF parameters that were independent of age, sex, body mass, height, body mass index, and Tanner stages. CONCLUSIONS: We present Z score equations for several CRF parameters derived from a healthy pediatric population. These reference values provide updated predicted means and range of normality that are independent of sex and body size. Further testing is needed to assess if these reference values increase sensitivity and specificity to identify abnormal cardiorespiratory response in children with chronic diseases.

Aspirin Dose and Prevention of Coronary Abnormalities in Kawasaki Disease.

BACKGROUND: Acetylsalicylic acid (ASA) is part of the recommended treatment of Kawasaki disease (KD). Controversies remain regarding the optimal dose of ASA to be used. We aimed to evaluate the noninferiority of ASA at an antiplatelet dose in acute KD in preventing coronary artery (CA) abnormalities. METHODS: This is a multicenter, retrospective, nonrandomized cohort study including children 0 to 10 years of age with acute KD between 2004 and 2015 from 5 institutions, of which 2 routinely use low-dose ASA (3-5 mg/kg per day) and 3 use high-dose ASA (80 mg/kg per day). Outcomes were CA abnormalities defined as a CA diameter with a z score ≥2.5. We assessed the risk difference of CA abnormalities according to ASA dose. All subjects received ASA and intravenous immunoglobulin within 10 days of fever onset. RESULTS: There were 1213 subjects included, 848 in the high-dose and 365 in the low-dose ASA group. There was no difference in the risk of CA abnormalities in the low-dose compared with the high-dose ASA group (22.2% vs 20.5%). The risk difference adjusted for potential confounders was 0.3% (95% confidence interval [CI]: -4.5% to 5.0%). The adjusted risk difference for CA abnormalities persisting at the 6-week follow-up was -1.9% (95% CI: -5.3% to 1.5%). The 95% CI of the risk difference of CA abnormalities adjusted for confounders was within the prespecified 5% margin considered to be noninferior. CONCLUSIONS: In conjunction with intravenous immunoglobulin, low-dose ASA in acute KD is not inferior to high-dose ASA for reducing the risk of CA abnormalities.