Genetic impact dominates over environmental effects in development of carotid artery stiffness: a twin study

Comparison between Carotid Distensibility-Based Vascular Age and Risk-Based Vascular Age in Middle-Aged Population Free of Cardiovascular Disease

The concept of vascular age (VA) was proposed to provide patients with an understandable explanation of cardiovascular (CV) risk and to improve the performance of prediction models. The present study compared risk-based VA derived from Framingham Risk Score (FRS) and Systematic Coronary Risk Estimation (SCORE) models with value-based VA derived from the measurement of the common carotid artery (CCA) distensibility coefficient (DC), and it assessed the impact of DC-based VA on risk reclassification. In 528 middle-aged individuals apparently free of CV disease, DC was measured by radiofrequency-based arterial wall tracking that was previously utilised to establish sex- and age-specific reference values in a healthy population. DC-based VA represented the median value (50th percentile) for given sex in the reference population. FRS-based and SCORE-based VA was calculated as recommended. We observed a good agreement between DC-based and FRS-based VA, with a mean difference of 0.46 ± 12.2 years (p = 0.29), while the mean difference between DC-based and SCORE-based VA was higher (3.07 ± 12.7 years, p < 0.0001). When only nondiabetic individuals free of antihypertensive therapy were considered (n = 341), the mean difference dropped to 0.70 ± 12.8 years (p = 0.24). Substitution of chronological age with DC-based VA in FRS and SCORE models led to a reclassification of 28% and 49% of individuals, respectively, to the higher risk category. Our data suggest that the SCORE prediction model, in which diabetes and antihypertensive treatment are not considered, should be used as a screening tool only in healthy individuals. The use of VA derived from CCA distensibility measurements could improve the performance of risk prediction models, even that of the FRS model, as it might integrate risk prediction with additional risk factors participating in vascular ageing, unique to each individual. Prospective studies are needed to validate the role of DC-based VA in risk prediction.

Vertebral Artery Diameter and Flow: Nature or Nurture

BACKGROUND AND PURPOSE

In contrast with the carotid arteries, the vertebral arteries (VAs) show considerable variation in length, caliber, and vessel course. This study investigated whether the variation in diameter and flow characteristics of the VAs might be inherited.

METHODS

A total of 172 Italian twins from Padua, Perugia, and Terni (54 monozygotic, 32 dizygotic) recruited from the Italian Twin Registry underwent B-mode and pulsed-wave Doppler ultrasound assessment of their VAs. VA diameters, peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at the level of a horizontal V2 segment. Univariate quantitative genetic modeling was performed.

RESULTS

Fourteen percent of the sample had VA hypoplasia. Within pair correlation in monozygotic twins was higher than in dizygotics (.552 vs. .229) for VA diameter. Age- and sex-adjusted genetic effect, under the most parsimonious model, accounted for 54.7% (95% CI: 42.2-69.1%) of the variance of VA diameter, and unshared environmental effect for 45.3% (95% CI: 30.9-57.8%). No heritability was found for the PSV of VA, but shared (34.1%; 95% CI: 16.7-53.7%) and unshared (65.9%; 95% CI: 45.9-83.1%) environmental factors determined the variance. EDV of VA is moderately genetically influenced (42.4%; 95% CI: 16.1-64.9%) and also determined by the unshared environment (57.6%; 95% CI: 34.7-83.7%).

CONCLUSIONS

The diameter of the VAs is moderately genetically determined. Different factors influence the PSV and EDV of VAs, which may highlight the complex hemodynamic background of VA flow and help to understand the vertebral flow anomalies found by ultrasound.

Evidence for contemporary arterial stiffening in obese children and adolescents using pulse wave velocity: A systematic review and meta-analysis

INTRODUCTION

Pulse wave velocity (PWV) and augmentation index (AI) may provide information on future cardiovascular risk. Reports are conflicting on whether obese children show evidence of raised PWV and AI.

METHODS

Systematic review and meta-analysis of published studies using EMBASE, Web-of-Science and PUBMED databases for studies reporting PWV and AI in obese versus non-obese controls(<age 18 years). Studies were pooled in meta-analyses to generate weighted mean differences (WMD) using random effects methodology. Analyses were repeated by method, quality grade and anatomical region.

RESULTS

383 studies were found in initial searches and 81 were assessed in detail; 14 studies (6677 total participants, 1120 obese and 5557 non-obese) were suitable for meta-analysis for PWV, and 5 studies (728 participants obese and 317 non-obese) for AI. Across all studies, obese children had higher PWV than non-obese children (WMD 0.45(95% confidence interval 0.10 to 0.81 ms(-)(1))). This difference was not significant when only studies with low/medium risk of bias were included. Obese subjects had higher PWV measured directly at the carotid (WMD 0.51 (0.35-0.67 ms(-)(1))) and aorta (WMD 1.33 (0.36-2.31)). No significant differences were found for AI. Heterogeneity was high in all analyses(I(2) > 90% in PWV and AI meta-analyses).

CONCLUSION

There is moderate evidence that obese children have increased arterial stiffening, especially in central arteries. This supports concerns about future CVD risk in obese children. Developing effective obesity interventions must remain a health priority.