Association of Apolipoproteins B and A-1 With Markers of Vascular Health or Cardiovascular Events

BACKGROUND: Apolipoprotein B (apoB) and apolipoprotein A-1 (apoA-1) are markers of lipoprotein metabolism. Although their relationship to cardiovascular disease has been well documented, little is known regarding their correlation to measures of vascular structure and function. This study was conducted to investigate the relationship between apoA-1, apoB, and measures of vascular function, as well their relationship to adverse cardiovascular events. Moreover, we evaluated whether apoB or the apoB/apoA-1 ratio was more closely related to vascular markers than was low-density lipoprotein cholesterol (LDL-C) or non-high-density lipoprotein cholesterol (non-HDL-C). METHODS: One thousand five hundred twenty-two healthy middle-aged men of the Firefighters and Their Endothelium (FATE) cohort were assessed for risk factors and flow-mediated dilatation (FMD), hyperemic velocity (VTI), and carotid intima-media thickness (CIMT). Participants were then followed for 7.2 ± 1.7 years. ApoA-1 and apoB levels were measured at baseline. RESULTS: ApoA-1 was not correlated with VTI, FMD, or CIMT, whereas apoB was significantly related to VTI and CIMT. Multiple regression analyses confirmed apoB as being related to both VTI (β = -0.083; P = 0.001) and CIMT (β = 0.055; P = 0.022) in models adjusted for age; blood pressure; high-density lipoprotein C (HDL-C), triglyceride and insulin levels; waist circumference; and C-reactive protein levels. In substituted models, LDL-C (β = -0.092; P < 0.001) and non-HDL-C (β = -0.089; P = 0.001) levels appeared to have the same degree of association as apoB for VTI but were not associated with CIMT. ApoB was found to be associated with cardiovascular events (hazard ratio, 1.349; 95% confidence interval, 1.073-1.695; P = 0.010). CONCLUSIONS: ApoB had an independent but weak relationship with indices of microvascular health. Nevertheless, it was associated with occurrence rates of adverse cardiovascular events.