Subclinical Atherosclerosis in Adolescents and Young Adults and the Risk of Cardiovascular Disease: the Strong Heart Family Study (SHFS).

Introduction: Rates of cardiovascular disease (CVD) among American Indians (AI) have been increasing. Subclinical atherosclerosis is typically detected later in life and may develop into clinical CVD. Although investigators have established the association in older adults, the burden of subclinical atherosclerosis and its relation to CVD risk among AI youth is unclear. Hypothesis: Subclinical atherosclerosis will be prevalent and the risk of CVD will be higher in AI with atherosclerotic plaque in adolescence and early adulthood. Methods: We evaluated AI participants from the SHFS, who were 14-39 years old, CVD free, and had a carotid ultrasound at the baseline examination, 2001-2003 (n=1,376). We used carotid ultrasound to detect baseline atherosclerotic plaque. We identified fatal and/or non-fatal CVD events through the end of 2019 with a median follow-up of 17.8 years. We used shared frailty Cox Proportional Hazards models to assess the association between subclinical atherosclerosis and time to CVD events, while controlling for covariates. Results: Among 1,376 participants, 71 (5.2%) had atherosclerotic plaque at baseline. During follow-up, 120 (8.7%) participants had a fatal or non-fatal CVD event. CVD incidence was higher in participants with baseline plaque (13.51/1,000 person-years) than in those without (4.95/1,000 person-years, p=0.0003, Figure 1). Risk of CVD was higher in participants with baseline plaque compared to those without, while controlling for age and obesity (CVD HR=1.85, 95% CI=1.02-3.37, p=0.0420). Conclusions: AI adolescents and young adults have an unexpectedly high prevalence of atherosclerotic plaque, which is independently associated with incident CVD later in life. Thus, atherosclerosis begins early in life and interventions in adolescents and young adults to slow the progression of disease could prevent or delay CVD events later in life.