Using a non-invasive technique known as pulse waveform analysis, investigators determined that elasticity of both small and large blood vessels is reduced -- an indicator of atherosclerosis -- in untreated people with HIV, according to a report in the September 2009 Journal of Acquired Immune Deficiency Syndromes.

A growing body of research indicates that people with HIV have a higher risk of cardiovascular disease, but it is not yet clear whether this is due to HIV infection itself, antiretroviral therapy (ART), or traditional cardiovascular risk factors in an aging population.

Atherosclerosis, or loss of elasticity and build-up of plaque within the arteries, can restrict blood supply to the heart, leading to myocardial infarction. Recent research indicates that HIV infection is an independent risk factor for atherosclerosis based on measurement of carotid intima-media thickness, or thickness of the walls of the major arteries in the neck. Now, a study using a different technique has produced concordant results.

Jason Baker and colleagues estimated large and small artery elasticity in 32 untreated HIV positive study participants and 30 HIV negative control subjects by analyzing radial pulse waveforms, a technique that reveals evidence of early, preclinical atherosclerosis. Individuals with pre-existing clinical atherosclerotic disease (e.g., previous myocardial infarction or chronic angina) were excluded.

Differences in elasticity were compared with and without adjustment for Framingham cardiovascular risk. The researchers also took into account demographic characteristics and risk factors including sex, age, race/ethnicity, smoking, injection drug use, hepatitis C virus (HCV) coinfection, and high-density lipoprotein (HDL or "good") and non-HDL cholesterol levels.

Results

	HIV infection was associated with reduced large artery elasticity (-2.55 mL/mm Hg × 10; P = 0.02) and small artery elasticity (-1.50 mL/mm Hg × 100; P = 0.02).
	Associations with traditional risk factors were often stronger for small compared with large artery elasticity.
	After adjusting for other factors, artery elasticity differences between HIV positive and HIV negative participants were similar regardless of method of analysis.
	HCV coinfection was associated with reduced small artery elasticity, but its effect on large artery elasticity did not reach statistical significance.
	Fasting blood lipid levels were not significantly associated with large or small artery elasticity.
	CD4 cell count and HIV RNA level likewise were not associated with large or small artery elasticity among HIV positive participants.

"Untreated HIV infection is associated with impaired arterial elasticity, of both the large and small vasculature, after controlling for additional risk factors," the study authors concluded. "The degree of HIV-related impairment reported in arterial elasticity is clinically relevant."

"Pulse waveform analysis is a noninvasive technique to assess cardiovascular disease risk that should be evaluated in larger studies of HIV-infected persons," they added.

Large artery elasticity reflects damage to major central arteries, while small artery elasticity reflects the condition of the peripheral or distal circulation. "Our findings suggest that HIV-mediated vessel damage and dysfunction are present throughout the arterial vasculature," the researchers noted.

While the mechanisms underlying blood vessel damage and cardiovascular disease in HIV positive people is not fully understood, the authors suggested that inflammation and immune activation related to chronic viral infection likely plays a role.

Department of Medicine, Hennepin County Medical Center, Minneapolis, MN; School of Medicine and Department of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN.

9/11/09

Reference
JV Baker, D Duprez, J Rapkin, and others. Untreated HIV Infection and Large and Small Artery Elasticity. Journal of Acquired Immune Deficiency Syndromes 52(1): 25-31. September 2009. (Abstract).