Familial aggregation of carotid artery intima media thickness: a three-generation study

BACKGROUND: Family history of premature cardiovascular events (FHPCE) is an independent risk factor for atherosclerosis and for vascular events, partially explainable by genetic or environmental atherosclerosis risk factors. Carotid intima media thickness (IMT) is a widely accepted subclinical marker of carotid and coronary atherosclerosis. On this basis, some authors have tried to confirm the nature of FHPCE as a risk factor for atherosclerosis by evaluating the amount of “offspring-carotid IMT variability” explained by parent’s IMT. These studies, however, reported contrasting results with an amount of offspring IMT variability explained by parent’s IMT ranging from 20 to 92%.(Moskau S et al., Stroke 2005;36;5-8) We hypothesized that these discrepancies might be related to the age of generational pairs (parent – offspring) studied. The contribution of parent’s-IMT to offspring-IMT variability in relatively young generational pairs (for example when parent-age is lower than 60) might, in fact, be different from the one evaluated in generational pairs relatively older (for example parent-age>75) in which environmental factors might have had the time to act as confounders. METHODS: Sixty-seven grandchildren (33 men and 34 women), one of their parents (37 men and 30 women) and one of their grandparents (18 men and 49 women), were recruited. Each of them had their CC-IMTmean, Bif-IMTmean, ICA-IMTmean and IMTmean measured by B-Mode ultrasound. Simple linear regression analysis was used to investigate correlations between carotid IMT in the young generational pairs (grandchildren vs parents) as well as in the old generational pairs (parents vs grandparents). For each generational pairs, the squared correlation coefficient (r2) was used to evaluate the extent of offspring’s carotid IMT variability explained by the carotid IMT of their respective parents. RESULTS: The mean age (±SD) of grandparents, parents and children was 70±8.3, 44±9.1 and 14±8.7, respectively. The corresponding figures for IMTmean was 1.17±0.19 mm, 1.11±0.35 mm and 1.06±0.28 mm, respectively. Mean carotid IMT variables of progenitors correlated with carotid IMT of their offspring in the young generational pairs (IMTmean: r2 =0.34 p<0.0001; IMTmax: r2 =0.21, p=0.001) but not in the old generational pairs. CONCLUSIONS: Familial aggregation of carotid IMT is better appreciable in the young generational pairs. This may be due to the higher prevalence of potential confounding environmental factors in the older generational pairs.