Abstract 080: A 15-year Cumulative High Exposure to Lean Mass and Blood Pressure but not Fat Mass predicts the 7-year change in Carotid-Femoral Pulse Wave Velocity and Carotid Intima-Media Thickness: The ALSPAC study
Authors: Agbaje Andrew O , Barker Alan R , Tuomainen Tomi-Pekka 
Published: May 2021

Introduction:
Evidence on the associations of fat mass and lean mass with changes in carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (cIMT), markers of pre-clinical atherosclerosis, from adolescence through young adulthood is lacking. Previous studies have reported strong associations of body mass index (BMI), a measure of adiposity, with these markers. However, it is unclear if increased BMI in relation to these markers represents a pathological process or physiological adaptation. A knowledge gap also exists on the independent associations of blood pressure (BP) measured from childhood through young adulthood with changes in cfPWV and cIMT between ages 17 and 24.5 years.

Hypothesis:
We assessed the hypothesis whether lean mass and systolic BP, independent of fat mass, cardiometabolic and lifestyle factors, measured at age 9, 17, and 24.5 years drive a 7-year change in cfPWV and cIMT.

Methods:
We studied 3863 British children from the Avon Longitudinal Study of Parents and Children's birth cohort (56% females). fat mass and lean mass were measured by dual-energy Xray absorptiometry, systolic and diastolic BP by Omron BP/pulse monitor, cfPWV by Vicorder device, and cIMT by CardioHealth ultrasound scan. All exposures were categorized in tertiles of low, normal, and high, with the low category as the reference group. We conducted linear mixed effect model analyses and adjusted for age, sex, low-density lipoprotein, C-reactive protein, fasting blood glucose, moderate to vigorous physical activity, smoking status, family history of cardiometabolic diseases, time in years between measure at 9 and 24.5 years, and systolic BP, fat mass, and/or lean mass depending on the predictor.

Results:
Participants mean (SD) age in years at different time points were [9.83 (0.30); 17.72 (0.33); 24.54 (0.73)]. Over a 15-year follow-up period, persistent exposure to high lean mass
effect estimate
=0.006 (CI 0.001 - 0.010, p=0.022), high systolic BP 0.013 (0.009 - 0.017, p<0.0001), and high diastolic BP 0.023 (0.019 - 0.027, p<0.0001), were independently associated with a 7-year increase in cfPWV. Accumulated fat mass and BMI were not related to cfPWV changes. Cumulative exposure to high lean mass 0.012 (0.008 - 0.016, p<0.0001), high BMI 0.007 (0.003 - 0.011, p=0.001) and high systolic BP 0.010 (0.006 - 0.014, p<0.0001) were independently associated with a 7-year increase in cIMT. fat mass and Diastolic BP were not associated with cIMT changes.

Conclusion:
For the first time, we showed in a healthy cohort that persistent exposure to higher lean mass and BP from childhood independently drives arterial wall adaptation in early adulthood. These arterial changes are likely normal responses to growth and maturation rather than subclinical signs of arterial diseases. Thus, cumulative exposure to high BMI in relation to higher cfPWV and cIMT may not indicate a deleterious effect of adiposity.