The MACS is an ongoing prospective observational study that enrolled MSM in four major US cities. This report presents data on both the incidence and progression of CAC among 825 men (541 HIV+ and 284 HIV-) who participated in the Multicenter AIDS Cohort Study (MACS) and underwent two or more cardiac CT scans over a mean follow-up of 5 years (range 2-8). Major objective was to investigate whether HIV+ compared with HIV- men are at greater risk for either incidence or progression of CAC after controlling for HIV-associated risk factors, especially duration of ART as well as traditional CVD risk factors.

Active MACS participants over 40 years of age, without a history of prior coronary or cerebrovascular disease, and who weighed less than 300 pounds were invited to undergo noncontrast CT scanning beginning in 2004 during the initial MACS CVD study (CVD1). Baseline CT scanning was completed in 945 men and 794 had a second CT scan a median 2.9 years later. The second MACS CVD study (CVD2) was initiated in 2010 and included both coronary CT angiography and noncontrast CAC scans. Analysis was restricted to men with at least two CAC scans (N=825, 541 HIV+ and 284 HIV-).

During follow-up, a higher hazard rate for incident CAC was observed in HIV+ than HIV- men (21.0 vs. 16.4%, respectively). The HR for CAC incidence among HIV+ compared with HIV- men was 1.74 (95% CI 1.15–2.62) adjusted for race, study site, and cohort period (Model 1). The HR was 1.76 (1.14–2.70), even after additional adjustment for smoking history, BMI, SBP, use of antihypertensive medication, fasting glucose, total cholesterol, LDL-C, triglycerides, lipid-lowering medication usage and HOMA-IR (Model 2). The HR was 1.64 (1.07–2.53) after further adjustment for the average value of covariates over the entire duration of follow-up (Model 3).

Among HIV+ men, factors associated with an increased hazard of incident CAC included current smoking, 2.26 (1.25– 4.10) and increased HOMA-IR (log-transformed), 1.67 (1.05–2.65). No associations were observed for dyslipidemia, duration of HAART usage, HIV RNA level, or CD4 + cell count/µl nadir and incident CAC.

Progression of CAC occurred in the great majority of men among whom CAC was present at baseline. Among 267 men with CAC above 10 at baseline, higher CAC Agatston scores were observed during follow-up in 258 of 267 (97%) with no difference observed by HIV serostatus in the proportion of men with CAC progression (96% of HIV+ and 97% of HIV-men). Overall, rates of progression were not significantly different by HIV serostatus; however, these data reflect the natural history of coronary artery calcification as the amount of CAC roughly doubles every 3–5 years.

Conclusions : In this large study of HIV+ and HIV- men who underwent serial cardiac CT scan imaging, HIV+ men were at significantly higher risk for development of CAC. In addition, two important and modifiable risk factors were identified for increased incidence of CAC. Taken together, these findings underscore the potential importance for smoking cessation and interventions to improve insulin resistance among HIV+ men.