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Cardiac CT angiography points to preclinical atherosclerosis in HIV+ men
 
 
 
 
JANUARY 15, 2010 | Shelley Wood, http://www.theheart.org
 
"we wanted to perform this study-to try to find out whether patients with HIV did indeed have an increased risk of subclinical coronary atherosclerosis compared with non-HIV-infected individuals with similar cardiovascular risk factors........CTA (coronary computed-tomography angiography) results showed that the HIV-infected men had a higher prevalence of coronary atherosclerosis, higher overall plaque volume, and a greater number of coronary segments containing plaque......But what was interesting was that we observed that total duration of time since HIV diagnosis was associated with plaque burden, as measured by number of segments with plaque and plaque volume, as well as the Agatston calcium score........The CD4/CD8 ratio, cytomegalovirus (CMV) IgG titer, and monocyte chemotactic protein-1 (MCP-1) were also associated with plaque....These findings suggest that there may be something happening in HIV patients of an inflammatory or infectious nature that might be potentially playing a role in terms of development of atherosclerosis, in addition to the role traditional risk factors play, she said.
 
Boston, MA - Another imaging study-this time using coronary computed-tomography angiography (CTA)-should help confirm what other studies have previously suggested: that HIV-infected men have a higher prevalence of preclinical atherosclerosis than men without HIV [1]. According to study authors, led by Dr Janet Lo (Brigham and Women's Hospital, Boston, MA), the study is the first to use coronary CTA to screen for coronary atherosclerosis and/or stenosis and to quantify plaque burden.
 
Results from their study are published in the January 16, 2010 issue of AIDS. Recent imaging studies, using calcium scoring or carotid ultrasound, have produced mixed results regarding the link between the unique lipid profiles in HIV-positive individuals and the higher MI risk faced by this group. While the pathobiology and mechanisms are not fully understood, previous studies have illuminated specific cardiovascular effects of certain HIV medications but also point to vascular damage seemingly linked to the viral infection itself and associated inflammation.
 
Lo and colleagues screened 78 HIV-positive men (mean age 47) and compared their CTA results and traditional coronary disease risk factors with 32 matched, non-HIV-positive controls. None of the study participants had known cardiovascular disease. CTA results showed that the HIV-infected men had a higher prevalence of coronary atherosclerosis, higher overall plaque volume, and a greater number of coronary segments containing plaque.
 
"Even though both groups were similar in terms of their traditional CV risk factors-as reflected in their Framingham risk scores-and were asymptomatic, without angina or previously known heart disease, we found that the HIV group had higher prevalence of subclinical coronary atherosclerosis as measured by coronary CTA," Lo told heartwire.
 
Calcium scores were also significantly higher in the HIV group. These measures appeared to be higher in men with a longer history of HIV.
 
Almost 7% of HIV-positive men were found to have obstructive coronary artery disease, compared with none of the controls. Not surprisingly, presence of traditional coronary artery risk factors was associated with plaque burden, Lo observed. "But what was interesting was that we observed that total duration of time since HIV diagnosis was associated with plaque burden, as measured by number of segments with plaque and plaque volume, as well as the Agatston calcium score."
 
The CD4/CD8 ratio, cytomegalovirus (CMV) IgG titer, and monocyte chemotactic protein-1 (MCP-1) were also associated with plaque. "These findings suggest that there may be something happening in HIV patients of an inflammatory or infectious nature that might be potentially playing a role in terms of development of atherosclerosis, in addition to the role traditional risk factors play," she said.
 
Lo emphasized that HIV care providers, as well as cardiologists and endocrinologists who care for people with HIV, are by now well aware of the unique lipid concerns in this patient group. For example, LDL levels are often normal in HIV-positive people, but HDL levels are typically depressed and triglycerides are high: in the current study, LDL levels were similar between the HIV and control groups. But studies examining preclinical heart disease in HIV populations have been conflicting, she said. "That was one of the main reasons we wanted to perform this study-to try to find out whether patients with HIV did indeed have an increased risk of subclinical coronary atherosclerosis compared with non-HIV-infected individuals with similar cardiovascular risk factors."
 
More studies
 
As with other cardiac CTA studies making waves in recent years, Lo et al's study did not examine whether increased plaque burden correlated with worse clinical outcomes. "Our study design-this was a cross-sectional study-doesn't allow us to answer that question, but that certainly is a very important question, and hopefully future studies will help to answer that," she said.
 
Lo et al's paper coincides with the publication of at least two larger studies in the HIV/AIDS arena addressing lipid effects of some of the major HIV drugs. Results of the SWITCHMARK 1 and 2 studies were published online January 13, 2010 in the Lancet, showing that HIV patients who switch from a lopinavir-ritonavir regimen to raltegravir can get better reductions in triglyceride and total- and non-HDL levels, but at the expense of lower suppression of their viral load (from Jules: this is not true, patients with long duration of prior ART use had drug resistance that undermined their response to switching to raltegravir but patients with no prior experience did well after switching) [2]. Elsewhere, researchers writing in the February 2010 issue of the Journal of Infectious Diseases report an additional year of follow-up from the DAD study showing that HIV medications lopinavir-ritonavir, indinavir, abacavir, and didanosine were all associated with an increased risk of MI, although the absolute increased risk appeared to be small [3].(from Jules: this is questionable to regarding abacavir, more recent studies found questions surrounding the association of abacavir with MI, that there may have been channeling bias and othrr potential confounders).
 
 
 
 
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