Real-world experience with edoxaban for anticoagulation in children at risk for coronary artery thrombosis.

BACKGROUND: Direct oral anticoagulants have the potential to improve care in children requiring chronic anticoagulation. Edoxaban has favourable pharmacokinetics that could benefit younger patients but data on long-term safety and efficacy for specific paediatric indications are lacking. STUDY AIMS: We present a single-centre experience using edoxaban in children who require chronic anticoagulation for large coronary artery aneurysms secondary to Kawasaki disease. METHODS: Weight-based dosing of once-daily oral edoxaban was offered as alternative to standard anticoagulation for patients aged 1-18 years. Chart review was performed for a median follow-up period of 49 months on edoxaban. Steady-state pharmacokinetics and pharmacodynamics of edoxaban were also explored. RESULTS: Sixteen patients on chronic therapy with edoxaban were included. No major bleeding events were reported. Two patients experienced coronary artery thrombosis after 23 and 38 months on edoxaban, 7 and 11 years after diagnosed with Kawasaki disease, respectively. This predicts 70% event-free rate at 12 years from diagnosis. Area under the curve estimates over the dosing interval of 24 hours were similar to those reported in adults. CONCLUSIONS: Edoxaban use is feasible and well-tolerated for long-term use in paediatric population. We suggest appropriate exposure using weight-based once-daily dosing strategy that may be comparable to standard-of-care anticoagulation in prevention of coronary artery thrombosis. Larger studies are needed to evaluate long-term safety and efficacy of edoxaban in this population.

Triiodothyronine Supplementation in Infants Undergoing Cardiopulmonary Bypass: A Randomized Controlled Trial.

Cardiopulmonary bypass (CPB) profoundly suppresses circulating thyroid hormone levels in infants. We performed a multicenter randomized placebo controlled trial to determine if triiodothyronine (T3) supplementation improves reduces time to extubation (TTE) in infants after CPB. Infants (n = 220) undergoing cardiac surgery with CPB and stratified into 2 age cohorts: ≤30 days and >30 days to <152 days were randomization to receive either intravenous triiodothyronine or placebo bolus followed by study drug infusion until extubated or at 48 hours, whichever preceded. T3 did not significantly alter the primary endpoint, TTE (hazard ratio for chance of extubation (1.08, 95% CI: 0.82-1.43, P = 0.575) in the entire randomized population with censoring at 21 days. T3 showed no significant effect on TTE (HR 0.82, 95% CI:0.55-1.23, P = 0.341) in the younger subgroup or in the older (HR 1.38, 95% CI:0.95-2.2, P = 0.095). T3 also did not significantly impact TTE during the first 48 hours while T3 levels were maintained (HR 1.371, 95% CI:0.942-1.95, P = 0.099) No significant differences occurred for arrhythmias or other sentinel adverse events in the entire cohort or in the subgroups. This trial showed no significant benefit on TTE in the entire cohort. T3 supplementation appears safe as it did not cause an increase in adverse events. The study implementation and analysis were complicated by marked variability in surgical risk, although risk categories were balanced between treatment groups.

First comprehensive identification of cardiac proteins with putative increased O-GlcNAc levels during pressure overload hypertrophy.

Protein posttranslational modifications (PTMs) by O-GlcNAc globally rise during pressure-overload hypertrophy (POH). However, a major knowledge gap exists on the specific proteins undergoing changes in O-GlcNAc levels during POH primarily because this PTM is low abundance and easily lost during standard mass spectrometry (MS) conditions used for protein identification. Methodologies have emerged to enrich samples for O-GlcNAcylated proteins prior to MS analysis. Accordingly, our goal was to identify the specific proteins undergoing changes in O-GlcNAc levels during POH. We used C57/Bl6 mice subjected to Sham or transverse aortic constriction (TAC) to create POH. From the hearts, we labelled the O-GlcNAc moiety with tetramethylrhodamine azide (TAMRA) before sample enrichment by TAMRA immunoprecipitation (IP). We used LC-MS/MS to identify and quantify the captured putative O-GlcNAcylated proteins. We identified a total of 700 putative O-GlcNAcylated proteins in Sham and POH. Two hundred thirty-three of these proteins had significantly increased enrichment in POH over Sham suggesting higher O-GlcNAc levels whereas no proteins were significantly decreased by POH. We examined two MS identified metabolic enzymes, CPT1B and the PDH complex, to validate by immunoprecipitation. We corroborated increased O-GlcNAc levels during POH for CPT1B and the PDH complex. Enzyme activity assays suggests higher O-GlcNAcylation increases CPT1 activity and decreases PDH activity during POH. In summary, we generated the first comprehensive list of proteins with putative changes in O-GlcNAc levels during POH. Our results demonstrate the large number of potential proteins and cellular processes affected by O-GlcNAc and serve as a guide for testing specific O-GlcNAc-regulated mechanisms during POH.

Tolerability of COVID-19 Infection and Messenger RNA Vaccination Among Patients With a History of Kawasaki Disease.

Importance: Kawasaki disease (KD) symptoms significantly overlap with multisystem inflammatory syndrome in children due to COVID-19. Patients with KD may be at risk for adverse outcomes from exposure to SARS-CoV-2 infection or vaccination. Objective: To describe the outcomes of patients with KD to SARS-CoV-2 infection or vaccination. Design, Setting, and Participants: This case series evaluated 2 cohorts using an existing KD database and reviewed individual electronic medical records for the period spanning January 1, 2020, through January 31, 2022, via electronic medical records that include Washington state immunization records. Vaccine cohort inclusion criteria consisted of being 21 years or younger at immunization and receiving 1 or more BNT162b2 (Pfizer-BioNTech) or messenger RNA (mRNA)-1273 (Moderna) vaccine doses. The COVID-19 cohort included patients 21 years or younger with positive polymerase chain reaction or nuclear capsid IgG findings for SARS-CoV-2. Participants included 826 patients from a preexisting KD database. One hundred fifty-three patients received at least 1 BNT162b2 or mRNA-1273 vaccine dose and were included in the mRNA vaccine cohort. Thirty-seven patients had positive test results for SARS-CoV-2 and were included in the COVID-19 cohort. Exposures: SARS-CoV-2 vaccination and/or infection. Main Outcomes and Measures: Adverse events after mRNA vaccination and/or COVID-19, including clinician visits, emergency department encounters, or hospitalizations. Results: Among the 153 patients included in the mRNA vaccination cohort (mean [SD] age, 13.0 [4.3] years; 94 male [61.4%]), the BNT162b2 vaccine was provided for 143 (93.5%), and the remaining 10 (6.5%) received mRNA-1273 or a combination of both. Among patients in the vaccine cohort, 129 (84.3%) were fully vaccinated or received a third-dose booster. No clinically severe adverse events occurred, and there were no reports of vaccine-related hospitalizations or outpatient visits. The COVID-19 cohort included 37 patients (mean [SD] age, 11.0 [5.5] years; 22 male [59.5%]). No patients required hospitalization due to COVID-19. The most common symptoms included low-grade fever, fatigue, cough, and myalgia with resolution within a few days. Two patients, aged 9 and 19 years, had extended cough and fatigue for 3 to 4 weeks. One patient developed COVID-19 within 6 weeks of receiving intravenous immunoglobulin for KD. Conclusions and Relevance: These findings suggest that the mRNA vaccines may be safe and COVID-19 may not be severe for patients with a history of KD.

Brain capillary obstruction during neurotoxicity in a mouse model of anti-CD19 chimeric antigen receptor T-cell therapy.

Immunotherapy for haematologic malignancies with CD19-directed chimeric antigen receptor T cells has been highly successful at eradicating cancer but is associated with acute neurotoxicity in ∼40% of patients. This neurotoxicity correlates with systemic cytokine release syndrome, endothelial activation and disruption of endothelial integrity, but it remains unclear how these mechanisms interact and how they lead to neurologic dysfunction. We hypothesized that dysfunction of the neurovascular unit is a key step in the development of neurotoxicity. To recapitulate the interaction of the intact immune system with the blood-brain barrier, we first developed an immunocompetent mouse model of chimeric antigen receptor T-cell treatment-associated neurotoxicity. We treated wild-type mice with cyclophosphamide lymphodepletion followed by escalating doses of murine CD19-directed chimeric antigen receptor T cells. Within 3-5 days after chimeric antigen receptor T-cell infusion, these mice developed systemic cytokine release and abnormal behaviour as measured by daily neurologic screening exams and open-field testing. Histologic examination revealed widespread brain haemorrhages, diffuse extravascular immunoglobulin deposition, loss of capillary pericyte coverage and increased prevalence of string capillaries. To measure any associated changes in cerebral microvascular blood flow, we performed in vivo two-photon imaging through thinned-skull cranial windows. Unexpectedly, we found that 11.9% of cortical capillaries were plugged by Day 6 after chimeric antigen receptor T-cell treatment, compared to 1.1% in controls treated with mock transduced T cells. The capillary plugs comprised CD45+ leucocytes, a subset of which were CD3+ T cells. Plugging of this severity is expected to compromise cerebral perfusion. Indeed, we found widely distributed patchy hypoxia by hypoxyprobe immunolabelling. Increased serum levels of soluble ICAM-1 and VCAM-1 support a putative mechanism of increased leucocyte-endothelial adhesion. These data reveal that brain capillary obstruction may cause sufficient microvascular compromise to explain the clinical phenotype of chimeric antigen receptor T-cell neurotoxicity. The translational impact of this finding is strengthened by the fact that our mouse model closely approximates the kinetics and histologic findings of the chimeric antigen receptor T-cell neurotoxicity syndrome seen in human patients. This new link between systemic immune activation and neurovascular unit injury may be amenable to therapeutic intervention.

Molecular characterization and investigation of the role of genetic variation in phenotypic variability and response to treatment in a large pediatric Marfan syndrome cohort.

PURPOSE: In a large cohort of 373 pediatric patients with Marfan syndrome (MFS) with a severe cardiovascular phenotype, we explored the proportion of patients with MFS with a pathogenic FBN1 variant and analyzed whether the type/location of FBN1 variants was associated with specific clinical characteristics and response to treatment. Patients were recruited on the basis of the following criteria: aortic root z-score > 3, age 6 months to 25 years, no prior or planned surgery, and aortic root diameter < 5 cm. METHODS: Targeted resequencing and deletion/duplication testing of FBN1 and related genes were performed. RESULTS: We identified (likely) pathogenic FBN1 variants in 91% of patients. Ectopia lentis was more frequent in patients with dominant-negative (DN) variants (61%) than in those with haploinsufficient variants (27%). For DN FBN1 variants, the prevalence of ectopia lentis was highest in the N-terminal region (84%) and lowest in the C-terminal region (17%). The association with a more severe cardiovascular phenotype was not restricted to DN variants in the neonatal FBN1 region (exon 25-33) but was also seen in the variants in exons 26 to 49. No difference in the therapeutic response was detected between genotypes. CONCLUSION: Important novel genotype-phenotype associations involving both cardiovascular and extra-cardiovascular manifestations were identified, and existing ones were confirmed. These findings have implications for prognostic counseling of families with MFS.

Temporal regulation of protein O-GlcNAc levels during pressure-overload cardiac hypertrophy.

Protein posttranslational modifications (PTMs) by O-linked ß-N-acetylglucosamine (O-GlcNAc) rise during pressure-overload hypertrophy (POH) to affect hypertrophic growth. The hexosamine biosynthesis pathway (HBP) branches from glycolysis to make the moiety for O-GlcNAcylation. It is speculated that greater glucose utilization during POH augments HBP flux to increase O-GlcNAc levels; however, recent results suggest glucose availability does not primarily regulate cardiac O-GlcNAc levels. We hypothesize that induction of key enzymes augment protein O-GlcNAc levels primarily during active myocardial hypertrophic growth and remodeling with early pressure overload. We further speculate that downregulation of protein O-GlcNAcylation inhibits ongoing hypertrophic growth during prolonged pressure overload with established hypertrophy. We used transverse aortic constriction (TAC) to create POH in C57/Bl6 mice. Experimental groups were sham, 1-week TAC (1wTAC) for early hypertrophy, or 6-week TAC (6wTAC) for established hypertrophy. We used western blots to determine O-GlcNAc regulation. To assess the effect of increased protein O-GlcNAcylation with established hypertrophy, mice received thiamet-g (TG) starting 4 weeks after TAC. Protein O-GlcNAc levels were significantly elevated in 1wTAC versus Sham with a fall in 6wTAC. OGA, which removes O-GlcNAc from proteins, fell in 1wTAC versus sham. GFAT is the rate-limiting HBP enzyme and the isoform GFAT1 substantially rose in 1wTAC. With established hypertrophy, TG increased protein O-GlcNAc levels but did not affect cardiac mass. In summary, protein O-GlcNAc levels vary during POH with elevations occurring during active hypertrophic growth early after TAC. O-GlcNAc levels appear to be regulated by changes in key enzyme levels. Increasing O-GlcNAc levels during established hypertrophy did not restart hypertrophic growth.

Protein O-GlcNAcylation levels are regulated independently of dietary intake in a tissue and time-specific manner during rat postnatal development.

AIM: Metabolic sources switch from carbohydrates in utero, to fatty acids after birth and then a mix once adults. O-GlcNAcylation (O-GlcNAc) is a post-translational modification considered as a nutrient sensor. The purpose of this work was to assess changes in protein O-GlcNAc levels, regulatory enzymes and metabolites during the first periods of life and decipher the impact of O-GlcNAcylation on cardiac proteins. METHODS: Heart, brain and liver were harvested from rats before and after birth (D-1 and D0), in suckling animals (D12), after weaning with a standard (D28) or a low-carbohydrate diet (D28F), and adults (D84). O-GlcNAc levels and regulatory enzymes were evaluated by western blots. Mass spectrometry (MS) approaches were performed to quantify levels of metabolites regulating O-GlcNAc and identify putative cardiac O-GlcNAcylated proteins. RESULTS: Protein O-GlcNAc levels decrease drastically and progressively from D-1 to D84 (13-fold, P < .05) in the heart, whereas the changes were opposite in liver and brain. O-GlcNAc levels were unaffected by weaning diet in any tissues. Changes in expression of enzymes and levels of metabolites regulating O-GlcNAc were tissue-dependent. MS analyses identified changes in putative cardiac O-GlcNAcylated proteins, namely those involved in the stress response and energy metabolism, such as ACAT1, which is only O-GlcNAcylated at D0. CONCLUSION: Our results demonstrate that protein O-GlcNAc levels are not linked to dietary intake and regulated in a time and tissue-specific manner during postnatal development. We have identified by untargeted MS putative proteins with a particular O-GlcNAc signature across the development process suggesting specific role of these proteins.

Variants in ADRB1 and CYP2C9: Association with Response to Atenolol and Losartan in Marfan Syndrome.

OBJECTIVE: To test whether variants in ADRB1 and CYP2C9 genes identify subgroups of individuals with differential response to treatment for Marfan syndrome through analysis of data from a large, randomized trial. STUDY DESIGN: In a subset of 250 white, non-Hispanic participants with Marfan syndrome in a prior randomized trial of atenolol vs losartan, the common variants rs1801252 and rs1801253 in ADRB1 and rs1799853 and rs1057910 in CYP2C9 were analyzed. The primary outcome was baseline-adjusted annual rate of change in the maximum aortic root diameter z-score over 3 years, assessed using mixed effects models. RESULTS: Among 122 atenolol-assigned participants, the 70 with rs1801253 CC genotype had greater rate of improvement in aortic root z-score compared with 52 participants with CG or GG genotypes (Time × Genotype interaction P = .005, mean annual z-score change ± SE -0.20 ± 0.03 vs -0.09 ± 0.03). Among participants with the CC genotype in both treatment arms, those assigned to atenolol had greater rate of improvement compared with the 71 of the 121 assigned to losartan (interaction P = .002; -0.20 ± 0.02 vs -0.07 ± 0.02; P < .001). There were no differences in atenolol response by rs1801252 genotype or in losartan response by CYP2C9 metabolizer status. CONCLUSIONS: In this exploratory study, ADRB1-rs1801253 was associated with atenolol response in children and young adults with Marfan syndrome. If these findings are confirmed in future studies, ADRB1 genotyping has the potential to guide therapy by identifying those who are likely to have greater therapeutic response to atenolol than losartan.

First characterization of glucose flux through the hexosamine biosynthesis pathway (HBP) in ex vivo mouse heart.

The hexosamine biosynthesis pathway (HBP) branches from glycolysis and forms UDP-GlcNAc, the moiety for O-linked ß-GlcNAc (O-GlcNAc) post-translational modifications. An inability to directly measure HBP flux has hindered our understanding of the factors regulating protein O-GlcNAcylation. Our goals in this study were to (i) validate a LC-MS method that assesses HBP flux as UDP-GlcNAc (13C)-molar percent enrichment (MPE) and concentration and (ii) determine whether glucose availability or workload regulate cardiac HBP flux. For (i), we perfused isolated murine working hearts with [U-13C6]glucosamine (1, 10, 50, or 100 µm), which bypasses the rate-limiting HBP enzyme. We observed a concentration-dependent increase in UDP-GlcNAc levels and MPE, with the latter reaching a plateau of 56.3 ± 2.9%. For (ii), we perfused isolated working hearts with [U-13C6]glucose (5.5 or 25 mm). Glycolytic efflux doubled with 25 mm [U-13C6]glucose; however, the calculated HBP flux was similar among the glucose concentrations at ∼2.5 nmol/g of heart protein/min, representing ∼0.003-0.006% of glycolysis. Reducing cardiac workload in beating and nonbeating Langendorff perfusions had no effect on the calculated HBP flux at ∼2.3 and 2.5 nmol/g of heart protein/min, respectively. To the best of our knowledge, this is the first direct measurement of glucose flux through the HBP in any organ. We anticipate that these methods will enable foundational analyses of the regulation of HBP flux and protein O-GlcNAcylation. Our results suggest that in the healthy ex vivo perfused heart, HBP flux does not respond to acute changes in glucose availability or cardiac workload.

O-GlcNAc Transferase Promotes Compensated Cardiac Function and Protein Kinase A O-GlcNAcylation During Early and Established Pathological Hypertrophy From Pressure Overload.

Background Protein posttranslational modifications by O-linked ß-N-acetylglucosamine (O-GlcNAc) increase with cardiac hypertrophy, yet the functional effects of these changes are incompletely understood. In other organs, O-GlcNAc promotes adaptation to acute physiological stressors; however, prolonged O-GlcNAc elevations are believed to be detrimental. We hypothesize that early O-GlcNAcylation improves cardiac function during initial response to pressure overload hypertrophy, but that sustained elevations during established pathological hypertrophy negatively impact cardiac function by adversely affecting calcium handling proteins. Methods and Results Transverse aortic constriction or sham surgeries were performed on littermate controls or cardiac-specific, inducible O-GlcNAc transferase knockout (OGTKO) mice to reduce O-GlcNAc levels. O-GlcNAc transferase deficiency was induced at different times. To evaluate the initial response to pressure overload, OGTKO was completed preoperatively and mice were followed for 2 weeks post-surgery. To assess prolonged O-GlcNAcylation during established hypertrophy, OGTKO was performed starting 18 days after surgery and mice were followed until 6 weeks post-surgery. In both groups, OGTKO with transverse aortic constriction caused significant left ventricular dysfunction. OGTKO did not affect levels of the calcium handling protein SERCA2a. OGTKO reduced phosphorylation of phospholamban and cardiac troponin I, which would negatively impact cardiac function. O-GlcNAcylation of protein kinase A catalytic subunit, a kinase for phospholamban, decreased with OGTKO. Conclusions O-GlcNAcylation promotes compensated cardiac function in both early and established pathological hypertrophy. We identified a novel O-GlcNAcylation of protein kinase A catalytic subunit, which may regulate calcium handling and cardiac function.

Etanercept With IVIg for Acute Kawasaki Disease: A Randomized Controlled Trial.

OBJECTIVES: Patients with Kawasaki disease can develop life-altering coronary arterial abnormalities, particularly in those resistant to intravenous immunoglobulin (IVIg) therapy. We tested the tumor necrosis factor α receptor antagonist etanercept for reducing both IVIg resistance and coronary artery (CA) disease progression. METHODS: In a double-blind multicenter trial, patients with Kawasaki disease received either etanercept (0.8 mg/kg; n = 100) or placebo (n = 101) subcutaneously starting immediately after IVIg infusion. IVIg resistance was the primary outcome with prespecified subgroup analyses according to age, sex, and race. Secondary outcomes included echocardiographic CA measures within subgroups defined by coronary dilation (z score >2.5) at baseline. We used generalized estimating equations to analyze z score change and a prespecified algorithm for change in absolute diameters. RESULTS: IVIg resistance occurred in 22% (placebo) and 13% (etanercept) of patients (P = .10). Etanercept reduced IVIg resistance in patients >1 year of age (P = .03). In the entire population, 46 (23%) had a coronary z score >2.5 at baseline. Etanercept reduced coronary z score change in those with and without baseline dilation (P = .04 and P = .001); no improvement occurred in the analogous placebo groups. Etanercept (n = 22) reduced dilation progression compared with placebo (n = 24) by algorithm in those with baseline dilation (P = .03). No difference in the safety profile occurred between etanercept and placebo. CONCLUSIONS: Etanercept showed no significant benefit in IVIg resistance in the entire population. However, preplanned analyses showed benefit in patients >1 year. Importantly, etanercept appeared to ameliorate CA dilation, particularly in patients with baseline abnormalities.

Health-Related Quality of Life in Children and Young Adults with Marfan Syndrome.

OBJECTIVE: To assess health-related quality of life (HRQOL) in a large multicenter cohort of children and young adults with Marfan syndrome participating in the Pediatric Heart Network Marfan Trial. STUDY DESIGN: The Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core Scales were administered to 321 subjects with Marfan syndrome (5-25 years). PedsQL scores were compared with healthy population norms. The impact of treatment arm (atenolol vs losartan), severity of clinical features, and number of patient-reported symptoms on HRQOL was assessed by general linear models. RESULTS: Mean PedsQL scores in children (5-18 years) with Marfan syndrome were lower than healthy population norms for physical (P ≤ .003) and psychosocial (P < .001) domains; mean psychosocial scores for adults (19-25 years) were greater than healthy norms (P < .001). HRQOL across multiple domains correlated inversely with frequency of patient-reported symptoms (r = 0.30-0.38, P < .0001). Those <18 years of age with neurodevelopmental disorders (mainly learning disability, attention-deficit/hyperactivity disorder) had lower mean PedsQL scores (5.5-7.4 lower, P < .04). A multivariable model found age, sex, patient-reported symptoms, and neurodevelopmental disorder to be independent predictors of HRQOL. There were no differences in HRQOL scores by treatment arm, aortic root z score, number of skeletal features, or presence of ectopia lentis. CONCLUSIONS: Children and adolescents with Marfan syndrome were at high risk for impaired HRQOL. Patient-reported symptoms and neurodevelopmental disorder, but not treatment arm or severity of Marfan syndrome-related physical findings, were associated with lower HRQOL.

Cardiac Management of the Patient With Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) results in a progressive cardiomyopathy that produces significant morbidity and mortality. To improve the quality of life in patients with DMD, cardiac care is focused on surveillance and management, with the goal of slowing the onset and progression of heart failure complications. The current article is intended to be an expanded review on the cardiac management data used to inform the 2018 DMD Care Considerations recommendations as well as be a discussion on clinical controversies and future management directions. The new cardiac guidance includes changes regarding noninvasive imaging surveillance of cardiac function and pharmacologic therapy. Many emerging therapies lack sufficient evidence-based data to be recommended in the 2018 DMD Care Considerations. These are discussed in the present article as clinical controversies and future directions. Important emerging therapies include new heart failure medications, mechanical circulatory support with ventricular assist devices, heart transplantation, and internal cardiac defibrillators. Future research studies should be focused on the risks and benefits of these advanced therapies in patients with DMD. We conclude this review with a brief discussion on the relationship between the heart and the recently developed medications that are used to directly target the absence of dystrophin in DMD.

Frequency of Ventricular Arrhythmias and Other Rhythm Abnormalities in Children and Young Adults With the Marfan Syndrome.

Patients with the Marfan syndrome (MFS) are at risk for sudden death. The contribution of arrhythmias is unclear. This study examines the prevalence of arrhythmias in children with the MFS and their relation to clinical and/or echocardiographic factors. Data from the Pediatric Heart Network randomized trial of atenolol versus losartan in MFS were analyzed (6 months to 25 years old, aortic root diameter z-score > 3.0, no previous aortic surgery and/or dissection). Baseline 24-hour ambulatory electrocardiographic monitoring was performed. Significant ventricular ectopy (VE) and supraventricular ectopy (SVE) were defined as ≥10 VE or SVE/hour, or the presence of high-grade ectopy. Three-year composite clinical outcome of death, aortic dissection, or aortic root replacement was analyzed. There were 274 analyzable monitors on unique patients from 11 centers. Twenty subjects (7%) had significant VE, 13 (5%) significant SVE; of these, 2 (1%) had both. None had sustained ventricular or supraventricular tachycardia. VE was independently associated with increasing number of major Ghent criteria (odds ratio [OR] = 2.13/each additional criterion, p = 0.03) and greater left ventricular end-diastolic dimension z-score (OR = 1.47/each 1 unit increase in z-score, p = 0.01). SVE was independently associated with greater aortic sinotubular junction diameter z-score (OR = 1.56/each 1 unit increase in z-score, p = 0.03). The composite clinical outcome (14 events) was not related to VE or SVE (p ≥ 0.3), but was independently related to heart rate variability (higher triangular index). In conclusion, in this cohort, VE and SVE were rare. VE was related to larger BSA-adjusted left ventricular size. Routine ambulatory electrocardiographic monitoring may be useful for risk stratification in select MFS patients.

Predictors of Rapid Aortic Root Dilation and Referral for Aortic Surgery in Marfan Syndrome.

Few data exist regarding predictors of rapid aortic root dilation and referral for aortic surgery in Marfan syndrome (MFS). To identify independent predictors of the rate of aortic root (AoR) dilation and referral for aortic surgery, we investigated the data from the Pediatric Heart Network randomized trial of atenolol versus losartan in young patients with MFS. Data were analyzed from the echocardiograms at 0, 12, 24, and 36 months read in the core laboratory of 608 trial subjects, aged 6 months to 25 years, who met original Ghent criteria and had an AoR z-score (AoRz) > 3. Repeated measures linear and logistic regressions were used to determine multivariable predictors of AoR dilation. Receiver operator characteristic curves were used to determine cut-points in AoR dilation predicting referral for aortic surgery. Multivariable analysis showed rapid AoR dilation as defined by change in AoRz/year > 90th percentile was associated with older age, higher sinotubular junction z-score, and atenolol use (R2 = 0.01) or by change in AoR diameter (AoRd)/year > 90th percentile with higher sinotubular junction z-score and non-white race (R2 = 0.02). Referral for aortic root surgery was associated with higher AoRd, higher ascending aorta z-score, and higher sinotubular junction diameter:ascending aorta diameter ratio (R2 = 0.17). Change in AoRz of 0.72 SD units/year had 42% sensitivity and 92% specificity and change in AoRd of 0.34 cm/year had 38% sensitivity and 95% specificity for predicting referral for aortic surgery. In this cohort of young patients with MFS, no new robust predictors of rapid AoR dilation or referral for aortic root surgery were identified. Further investigation may determine whether generalized proximal aortic dilation and effacement of the sinotubular junction will allow for better risk stratification. Rate of AoR dilation cut-points had high specificity, but low sensitivity for predicting referral for aortic surgery, limiting their clinical use. Clinical Trial Number ClinicalTrials.gov number, NCT00429364.

Influence of Aortic Stiffness on Aortic-Root Growth Rate and Outcome in Patients With the Marfan Syndrome.

The Pediatric Heart Network randomized trial of atenolol versus losartan in the Marfan syndrome showed no treatment differences in the rates of aortic-root growth or clinical outcomes. In this report we present treatment effects on aortic stiffness and determine whether baseline aortic stiffness predicts aortic-root growth and clinical outcomes. Echocardiograms at 0, 6, 12, 24, and 36 months from 608 subjects (6 months to 25 years) who met original Ghent criteria and had a maximum aortic-root z-score (ARz) >3 were centrally reviewed. Stiffness index (SI) and elastic modulus (EM) were calculated for aortic root and ascending aorta. Data were analyzed using multivariable mixed effects modeling and Cox regression. Heart rate-corrected aortic-root SI over 3 years decreased with atenolol but did not change with losartan (-0.298 ± 0.139 vs 0.141 ± 0.139/year, p = 0.01). In the entire cohort, above-median aortic-root SI (>9.1) and EM (>618 mm Hg) predicted a smaller annual decrease in ARz (p ≤0.001). Upper-quartile aortic-root EM (>914 mm Hg) predicted the composite outcome of aortic-root surgery, dissection, or death (hazard ratio 2.17, 95% confidence interval 1.02 to 4.63, p = 0.04). Crude 3-year event rates were 10.4% versus 3.2% for higher versus lower EM groups. In conclusion, atenolol was associated with a decrease in aortic-root SI, whereas losartan was not. Higher baseline aortic-root SI and EM were associated with a smaller decrease in ARz and increased risk for clinical outcomes. These data suggest that noninvasive aortic stiffness measures may identify patients at higher risk of progressive aortic enlargement and adverse clinical outcomes, potentially allowing for closer monitoring and more aggressive therapy.

Diagnosis and management of Duchenne muscular dystrophy, part 2: respiratory, cardiac, bone health, and orthopaedic management.

A coordinated, multidisciplinary approach to care is essential for optimum management of the primary manifestations and secondary complications of Duchenne muscular dystrophy (DMD). Contemporary care has been shaped by the availability of more sensitive diagnostic techniques and the earlier use of therapeutic interventions, which have the potential to improve patients' duration and quality of life. In part 2 of this update of the DMD care considerations, we present the latest recommendations for respiratory, cardiac, bone health and osteoporosis, and orthopaedic and surgical management for boys and men with DMD. Additionally, we provide guidance on cardiac management for female carriers of a disease-causing mutation. The new care considerations acknowledge the effects of long-term glucocorticoid use on the natural history of DMD, and the need for care guidance across the lifespan as patients live longer. The management of DMD looks set to change substantially as new genetic and molecular therapies become available.

AMPK activation counteracts cardiac hypertrophy by reducing O-GlcNAcylation.

AMP-activated protein kinase (AMPK) has been shown to inhibit cardiac hypertrophy. Here, we show that submaximal AMPK activation blocks cardiomyocyte hypertrophy without affecting downstream targets previously suggested to be involved, such as p70 ribosomal S6 protein kinase, calcineurin/nuclear factor of activated T cells (NFAT) and extracellular signal-regulated kinases. Instead, cardiomyocyte hypertrophy is accompanied by increased protein O-GlcNAcylation, which is reversed by AMPK activation. Decreasing O-GlcNAcylation by inhibitors of the glutamine:fructose-6-phosphate aminotransferase (GFAT), blocks cardiomyocyte hypertrophy, mimicking AMPK activation. Conversely, O-GlcNAcylation-inducing agents counteract the anti-hypertrophic effect of AMPK. In vivo, AMPK activation prevents myocardial hypertrophy and the concomitant rise of O-GlcNAcylation in wild-type but not in AMPKα2-deficient mice. Treatment of wild-type mice with O-GlcNAcylation-inducing agents reverses AMPK action. Finally, we demonstrate that AMPK inhibits O-GlcNAcylation by mainly controlling GFAT phosphorylation, thereby reducing O-GlcNAcylation of proteins such as troponin T. We conclude that AMPK activation prevents cardiac hypertrophy predominantly by inhibiting O-GlcNAcylation.

PPARα augments heart function and cardiac fatty acid oxidation in early experimental polymicrobial sepsis.

Children with sepsis and multisystem organ failure have downregulated leukocyte gene expression of peroxisome proliferator-activated receptor-α (PPARα), a nuclear hormone receptor transcription factor that regulates inflammation and lipid metabolism. Mouse models of sepsis have likewise demonstrated that the absence of PPARα is associated with decreased survival and organ injury, specifically of the heart. Using a clinically relevant mouse model of early sepsis, we found that heart function increases in wild-type (WT) mice over the first 24 h of sepsis, but that mice lacking PPARα (Ppara-/-) cannot sustain the elevated heart function necessary to compensate for sepsis pathophysiology. Left ventricular shortening fraction, measured 24 h after initiation of sepsis by echocardiography, was higher in WT mice than in Ppara-/- mice. Ex vivo working heart studies demonstrated greater developed pressure, contractility, and aortic outflow in WT compared with Ppara-/- mice. Furthermore, cardiac fatty acid oxidation was increased in WT but not in Ppara-/- mice. Regulatory pathways controlling pyruvate incorporation into the citric acid cycle were inhibited by sepsis in both genotypes, but the regulatory state of enzymes controlling fatty acid oxidation appeared to be permissive in WT mice only. Mitochondrial ultrastructure was not altered in either genotype indicating that severe mitochondrial dysfunction is unlikely at this stage of sepsis. These data suggest that PPARα expression supports the hyperdynamic cardiac response early in the course of sepsis and that increased fatty acid oxidation may prevent morbidity and mortality. NEW & NOTEWORTHY: In contrast to previous studies in septic shock using experimental mouse models, we are the first to demonstrate that heart function increases early in sepsis with an associated augmentation of cardiac fatty acid oxidation. Absence of peroxisome proliferator-activated receptor-α (PPARα) results in reduced cardiac performance and fatty acid oxidation in sepsis.