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Coronary Artery Plaque Linked to Low Fat in MACS Men With HIV
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18th Conference on Retroviruses and Opportunistic Infections, February 27-March 2, 2011, Boston
"for men with HIV, less fat (lower total abdominal tissue, lower abdominal subcutaneous fat, and lower thigh subcutaneous fat) pointed to a higher coronary plaque score and thus to a higher heart disease risk."
Mark Mascolini
Detectable coronary artery calcium correlated with greater visceral and liver fat in Multicenter AIDS Cohort Study (MACS) men with and without HIV [1]. In men with HIV, lower total abdominal fat, subcutaneous abdominal, and thigh fat correlated with a higher total coronary plaque score. For men without HIV, more subcutaneous abdominal tissue correlated with a worse total coronary plaque score.
MACS is an ongoing multicenter study of gay men with and at risk for HIV infection in the United States. This analysis involved 250 HIV-positive men and 110 HIV-negative men who underwent coronary computed tomography angiography from January 2010 through January 2011 to assess coronary artery plaque volume, which the MACS team quantified in a total plaque severity score. Study participants also had CT scans to measure coronary artery calcium, total abdominal tissue (TAT), visceral abdominal tissue (VAT), subcutaneous abdominal tissue (SAT), and subcutaneous thigh fat (STF). The MACS investigators defined fatty liver as liver Hounsfield Units at or below 40. Coronary calcified plaque and coronary calcium score are strong predictors of coronary heart disease.
Compared with the HIV-negative group, men with HIV were younger (average 53.8 versus 57.2) and more likely to be black or Hispanic (46% versus 37.3%), to have diabetes (34.8% versus 23.6%), to have high lipids (86.8% versus 72.7%), and to smoke (29.6% versus 23.6%). But the HIV group was less likely to be obese than the HIV-negative group (14.8% versus 22.7%). Men with HIV had less abdominal TAT (average 355 versus 419 cm[2]), abdominal SAT (190 versus 259 cm[2]), and STF (31 versus 60 cm[2]), but similar amounts of VAT (167 and 160 cm[2]). The HIV group was also more likely to have evidence of fatty liver (5.6% versus 2.7%).
Coronary artery calcium could be detected (Agatston score above 0) in 131 men (52.4%) with HIV and 63 (57.2%) without HIV. A model to evaluate the association of total Agatston score (above 0 versus 0) and fat deposits considered age, HIV status, history of hypertension, and tobacco smoking. Agatston score did not correlate with TAT, SAT, or STF in either group. But an Agatston score above 0 was associated with higher VAT (odds ratio [OR] 1.03 per 10-unit increase, 95% confidence interval [CI] 1.005 to 1.058, P = 0.02) and with fatty liver (OR 5.3, 95% CI 1.1 to 26.0, P = 0.04).
A model to evaluate the association of total plaque score with fat deposits factored in age, hyperlipidemia, tobacco smoking, insulin resistance, and HIV status. Higher TAT correlated with higher total plaque score in men without HIV (P = 0.01), but lower TAT correlated with higher total plaque in men with HIV (P = 0.001) (difference between HIV-positive and negative -0.021, P = 0.001). SAT also correlated positively with total plaque score in the HIV-negative group (P = 0.02), but again the association was negative in men with HIV (P = 0.001) (difference between HIV-positive and negative -0.035, P < 0.001).
STF was negatively associated with total plaque score in HIV-positive men (P = 0.008) (difference between HIV-positive and negative -0.112, P = 0.0016). In an unadjusted analysis, VAT correlated positively with total plaque score in men with and without HIV, but adjustment for age and comorbidities attenuated that correlation to the point of nonsignificance. Liver fat was not associated with total plaque score in HIV-positive or negative men.
Associations between total coronary plaque score and fat by HIV status
Abdominal subcutaneous fat area (SAT):
HIV-positive: Negative association, -0.0178, P = 0.0012
HIV-negative: Positive association, +0.0167, P = 0.0192
Abdominal visceral fat area (VAT):
HIV-positive: No significant association
HIV-negative: No significant association
Thigh subcutaneous fat area (STF):
HIV-positive: Negative association, -0.0624, P = 0.0082
HIV-negative: No significant association
Liver fat:
HIV-positive: No significant association
HIV-negative: No significant association
The MACS investigators concluded that "there were stronger associations between adiposity and subclinical atherosclerotic plaque . . . in HIV-negative men than HIV-positive men." But for men with HIV, less fat (lower total abdominal tissue, lower abdominal subcutaneous fat, and lower thigh subcutaneous fat) pointed to a higher coronary plaque score and thus to a higher heart disease risk.
Reference
1. Palella F, Li X, Jacobson L, et al. Associations between visceral and subcutaneous fat depots with total and calcified coronary plaque: the MACS. 18th Conference on Retroviruses and Opportunistic Infections. February 27-March 2, 2011. Boston. Abstract 806..
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