Assessment of coronary artery calcium by chest CT compared with EKG-gated cardiac CT in the multicenter AIDS cohort study

<div><p>Rationale</p><p>Individuals with HIV are at increased risk for coronary artery disease (CAD). Early detection of subclinical CAD by assessment of coronary artery calcium (CAC) may help risk stratify and prevent CAD events in these individuals. However, the current standard to quantify CAC i.e. Agatston scoring requires EKG-gated cardiac CT imaging.</p><p>Objective</p><p>To determine if the assessment of CAC using non-EKG-gated chest CT and the Weston scoring system is a useful surrogate for Agatston scores in HIV-infected and HIV-uninfected individuals.</p><p>Methods and measurements</p><p>CAC was assessed by both the Weston and Agatston score in 108 men enrolled in the Multicenter AIDS Cohort Study.</p><p>Results</p><p>Participants were 55.2 (IQR 50.4; 59.9) years old and 62 (57.4%) were seropositive for HIV. Inter-observer agreement (<i>r</i>_<i>s</i> = 0.94, κ = 90.0%, <i>p</i><0.001, <i>n</i> = 21) and intra-observer agreement (<i>r</i>_<i>s</i> = 0.95, κ = 95.2%, <i>p</i><0.001, <i>n</i> = 97) for category of Weston score were excellent. Weston scores were associated with similar CAD risk factors as Agatston scores (age, race, HDL cholesterol level, all <i>p</i><0.05) in our cohort. There was excellent correlation (<i>r</i>_<i>s</i> = 0.92, <i>p</i><0.001) and agreement (κ_w = 0.77, <i>p</i><0.001) between Weston and Agatston scores.</p><p>Conclusions</p><p>This study is the first to examine calcium scoring using chest CT in HIV-infected individuals and to independently validate the Weston score as a surrogate for the Agatston score. In clinical or research settings where EKG-gated cardiac CT is not feasible for the assessment of coronary calcium, Weston scoring by using chest CT should be considered.</p></div

Correlation between Weston and Agatston scores performed on 108 individuals.

<p>Correlation between Weston and Agatston scores performed on 108 individuals.</p

HIV Infection Is Associated with Increased Fatty Infiltration of the Thigh Muscle with Aging Independent of Fat Distribution

<div><p>Background</p><p>Lower muscle density on computed tomography (CT) provides a measure of fatty infiltration of muscle, an aspect of muscle quality that has been associated with metabolic abnormalities, weakness, decreased mobility, and increased fracture risk in older adults. We assessed the cross-sectional relationship between HIV serostatus, age, thigh muscle attenuation, and thigh muscle cross-sectional area (CSA).</p><p>Methods</p><p>Mean CT-quantified Hounsfield units (HU) of the thigh muscle bundle and CSA were evaluated in 368 HIV-infected and 145 HIV-uninfected men enrolled in the Multicenter AIDS Cohort Study (MACS) Cardiovascular Substudy using multivariable linear regression. Models all were adjusted for HIV serostatus, age, race, and body mass index (BMI); each model was further adjusted for covariates that differed by HIV serostatus, including insulin resistance, hepatitis C, malignancy, smoking, alcohol use, and self-reported limitation in physical activity.</p><p>Results</p><p>HIV-infected men had greater thigh muscle CSA (p<0.001) but lower muscle density (p<0.001) compared to HIV-uninfected men. Muscle density remained lower in HIV-infected men (p = 0.001) when abdominal visceral adiposity, and thigh subcutaneous adipose tissue area were substituted for BMI in a multivariable model. Muscle density decreased by 0.16 HU per year (p<0.001) of increasing age among the HIV-infected men, but not in the HIV-uninfected men (HIV x age interaction -0.20 HU; p = 0.002).</p><p>Conclusion</p><p>HIV-infected men had lower thigh muscle density compared to HIV-uninfected men, and a more pronounced decline with increasing age, indicative of greater fatty infiltration. These findings suggest that lower muscle quality among HIV-infected persons may be a risk factor for impairments in physical function with aging.</p></div

Inter observer agreement for Weston coronary artery calcium score, n = 21 scans.

<p>Inter observer agreement for Weston coronary artery calcium score, n = 21 scans.</p

ROC curves for the selection of the optimal cut point for the Weston score that corresponds to the established cut point of 100 (panel A) and 400 (panel B) for the Agatston score.

<p>ROC curves for the selection of the optimal cut point for the Weston score that corresponds to the established cut point of 100 (panel A) and 400 (panel B) for the Agatston score.</p

Factors Associated with Thigh Muscle Density (TMD) among HIV-infected Men.

<p>Multivariable model includes age, race, BMI plus other factors associated with TMD in univariate models.</p

Pearson Correlations (r) between age, BMI, grip strength, thigh muscle cross sectional area, thigh muscle density (TMD), visceral adipose area, thigh subcutaneous adipose area and insulin resistance among HIV-infected and HIV-uninfected men.

<p>Pearson Correlations (r) between age, BMI, grip strength, thigh muscle cross sectional area, thigh muscle density (TMD), visceral adipose area, thigh subcutaneous adipose area and insulin resistance among HIV-infected and HIV-uninfected men.</p

Differences in Muscle CSA and attenuation between HIV-infected vs uninfected groups.

<p>Differences in Muscle CSA and attenuation between HIV-infected vs uninfected groups.</p

Study population characteristics.

<p>Study population characteristics.</p