Growth of the aortic root in children and young adults with Marfan syndrome

Effects of childhood and adult height on later life cardiovascular disease risk estimated through Mendelian randomization

Taller individuals are at elevated and protected risk of various cardiovascular disease endpoints. Whether this is due to a direct consequence of their height during childhood, a long-term effect of remaining tall throughout the lifecourse, or confounding by other factors, is unknown. We sought to address this by harnessing human genetic data from the UK Biobank to separate the independent effects of childhood and adulthood height using an approach known as lifecourse Mendelian randomization (MR). Protective effects of taller childhood height on risk of later life coronary artery disease (OR = 0.78 per change in height category, 95% CI = 0.70 to 0.86, P = 4 × 10- 10) and stroke (OR = 0.93, 95% CI = 0.86 to 1.00, P = 0.03) using data from large-scale consortia were found using a univariable model, although evidence of these effects attenuated in a multivariable setting upon accounting for adulthood height. In contrast, direct effects of taller childhood height on increased risk of later life atrial fibrillation (OR = 1.61, 95% CI = 1.42 to 1.79, P = 5 × 10- 7) and thoracic aortic aneurysm (OR = 1.55, 95% CI = 1.16 to 1.95, P = 0.03) were found even after accounting for adulthood height. Evidence for both of these direct effects was replicated in the Million Veterans Program. The protective effect of childhood height on risk of coronary artery disease and stroke can be largely explained by taller children typically becoming taller individuals in later life. Conversely, the independent effect of childhood height on increased risk of atrial fibrillation and thoracic aortic aneurysm may point towards developmental mechanisms in early life which confer a lifelong risk on these disease outcomes.

Marfan syndrome: insights from animal models

Marfan syndrome (MFS) is an inherited disorder that affects the connective tissues and mainly presents in the bones, eyes, and cardiovascular system, etc. Aortic pathology is the leading cause of death in patients with Marfan syndrome. The fibrillin-1 gene (FBN1) is a major gene involved in the pathogenesis of MFS. It has been shown that the aortic pathogenesis of MFS is associated with the imbalances of the transforming growth factor-beta (TGF-β) signaling pathway. However, the exact molecular mechanism of MFS is unclear. Animal models may partially mimic MFS and are vital to the study of MFS. Several species of animals have been used for MFS studies, including chicks, cattle, mice, pigs, zebrafishes, Caenorhabditis elegans, and rabbits. These models were developed spontaneously or in combination with genetic engineering techniques. This review is to describe the TGF-β signaling pathway in MFS and the potential application of animal models to provide new therapeutic strategies for patients with MFS.

Pediatric sex estimation using AI-enabled ECG analysis: influence of pubertal development

AI-enabled ECGs have previously been shown to accurately predict patient sex in adults and correlate with sex hormone levels. We aimed to test the ability of AI-enabled ECGs to predict sex in the pediatric population and study the influence of pubertal development. AI-enabled ECG models were created using a convolutional neural network trained on pediatric 10-second, 12-lead ECGs. The first model was trained de novo using pediatric data. The second model used transfer learning from a previously validated adult data-derived algorithm. We analyzed the first ECG from 90,133 unique pediatric patients (aged ≤18 years) recorded between 1987-2022, and divided the cohort into training, validation, and testing datasets. Subgroup analysis was performed on prepubertal (0-7 years), peripubertal (8-14 years), and postpubertal (15-18 years) patients. The cohort was 46.7% male, with 21,678 prepubertal, 26,740 peripubertal, and 41,715 postpubertal children. The de novo pediatric model demonstrated 81% accuracy and an area under the curve (AUC) of 0.91. Model sensitivity was 0.79, specificity was 0.83, positive predicted value was 0.84, and the negative predicted value was 0.78, for the entire test cohort. The model's discriminatory ability was highest in postpubertal (AUC = 0.98), lower in the peripubertal age group (AUC = 0.91), and poor in the prepubertal age group (AUC = 0.67). There was no significant performance difference observed between the transfer learning and de novo models. AI-enabled interpretation of ECG can estimate sex in peripubertal and postpubertal children with high accuracy.

Midterm Clinical Outcomes of Reimplantation Versus Remodeling Valve-Sparing Aortic Root Replacement in Patients With Connective Tissue Disorders: A Meta-Analysis

This meta-analysis aimed to compare the midterm clinical outcomes of reimplantation versus remodeling techniques for valve-sparing aortic root replacement (VSARR) in patients with connective tissue disorders (CTDs). Studies were screened and identified after the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines from the PubMed, Web of Science, and Embase databases. Forest plots were produced using Review Manager 5.3 (Cochrane, UK). Studies comparing early and midterm clinical outcomes of reimplantation versus remodeling VSARR in patients with CTD with a mean age ≥18 years were included. The sensitivity analysis excluded studies and subgroups of patients that received ring or suture annuloplasty in addition to remodeling surgery. The study selection identified 9 eligible studies. After analysis of the study period and location for patient crossover, 7 retrospective studies consisting of 597 patients (301 reimplantation and 296 remodeling) were pooled. The pooling revealed no significant difference in postoperative mortality (estimated mean follow-up of 10.5 years) (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.30 to 1.48, I2 = 30%, p = 0.32), reoperation (OR 0.35, CI 0.04 to 3.30, I2 = 81%, p = 0.36), or occurrence of postoperative aortic regurgitation of ≥2 (OR 0.56, CI 0.31 to 1.02, I2 = 47%, p = 0.06). The sensitivity analysis excluding annuloplasty demonstrated improved mortality (OR 0.19, CI 0.06 to 0.64, I2 = 0%, p = 0.007) and decreased aortic regurgitation of ≥2 (OR 0.23, CI 0.10 to 0.53, I2 = 47%, p = 0.0005) in reimplantation VSARR. The rates of reoperation remained insignificant in the sensitivity analysis (OR 0.43, CI 0.05 to 3.53, I2 = 71%, p = 0.43). In conclusion, this meta-analysis has demonstrated no significant difference in the midterm clinical outcomes of reimplantation versus remodeling techniques of VSARR. The sensitivity analysis excluding studies and patient subgroups that received remodeling and annuloplasty suggests remodeling alone to be inferior to reimplantation in patients with CTDs. Further research is required to assess remodeling and annuloplasty against reimplantation in patients of this demographic because the current body of knowledge does not allow sufficient analysis.

Exaggerated elastin turnover in young individuals with Marfan syndrome: new insights from the AIMS trial

Aims

The fragmentation and loss of elastic fibre in the tunica media of the aorta are pathological hallmarks of Marfan syndrome (MFS) but the dynamics of elastin degradation and its relationship to aortic size and physiological growth remain poorly understood.

Methods and results

In this post hoc analysis of the AIMS randomized controlled trial, the association of plasma desmosine (pDES)-a specific biomarker of mature elastin degradation-with age and aortic size was analysed in 113 patients with MFS and compared to 109 healthy controls. There was a strong association between age and pDES in both groups, with higher pDES levels in the lower age groups compared to adults. During childhood, pDES increased and peaked during early adolescence, and thereafter decreased to lower adult levels. This trend was exaggerated in young individuals with MFS but in those above 25 years of age, pDES levels were comparable to controls despite the presence of aortic root dilation. In MFS children, increased aortic diameter relative to controls was seen at an early age and although the increase in diameter was less after adolescence, aortic root size continued to increase steadily with age. In MFS participants, there was an indication of a positive association between baseline pDES levels and aortic root dilatation during up to 5 years of follow-up.

Conclusion

This study has shown that developmental age has a significant effect on levels of elastin turnover as measured by pDES in MFS individuals as well as healthy controls. This effect is exaggerated in those with MFS with increased levels seen during the period of physiologic development that plateaus towards adulthood. This suggests an early onset of pathophysiology that may present an important opportunity for disease-modifying intervention.