Infection with HIV is associated with an
increased risk of heart attack, investigators from the United States report in
the Journal of the American Medical
Association Internal Medicine. Importantly, this finding was based upon
comparison of HIV-positive and HIV-negative individuals with the same
demographic and cardiovascular-risk profiles. Overall, infection with HIV was
associated with a 50% increase in the risk of heart attack beyond that
explained by other risk factors.
“HIV infection is independently associated
with AMI [acute myocardial infarction, or heart attack] after adjusting for
Framingham risk, comorbidities, and substance abuse,” comment the
Cardiovascular disease is an increasingly
important cause of serious illness and death in people with HIV. Earlier
research has found an association between infection with HIV and an increased
risk of heart attack. However, for the most part these studies did not
adequately control for confounding factors or had an inadequate control
population of HIV-negative people.
Investigators from the Veterans Aging
Cohort Study (VACS) Virtual Cohort (VC) therefore designed a large study with
well-matched patients and controls to examine whether HIV infection was
associated with an increased risk of heart attack, after taking into account
standard risk factors used to calculate Framingham risk scores (ten-year risk
of cardiovascular disease), co-infections such as hepatitis C virus, and
smoking, drug and alcohol use.
The study population comprised
approximately 84,500 individuals who were prospectively monitored between 2003
and 2009. Some 27,350 individuals were HIV positive. The HIV-negative controls were
well matched in terms of demographic characteristics. The mean age was approximately
48 years, 97% of participants were male and 48% were African Americans.
The Framingham risk score for both groups
was six, and the overall cardiovascular-risk profiles were simiular for the
patients and the controls. However, the HIV-infected participants were somewhat
more likely to smoke, and to have high triglycerides and lower HDL cholesterol.
During a median of 5.9 years of follow-up,
there were 871 heart attacks, 42% of which involved people with HIV.
After taking into account Framingham risk
factors, co-infections and substance abuse, HIV-positive participants were
approximately 50% more likely to experience a heart attack compared to the
HIV-negative controls (HR = 1.48; 95% CI, 1.27-1.72).
The associations between infection with HIV
and an increased risk of heart attack persisted when analysis was restricted to
participants who had never smoked (HR =1.75; 95% CI, 1.27-2.42) and those without
hepatitis C virus, renal disease or obesity (HR = 1.50; 95% CI, 1.20-1.88).
Expansion of the study population to include other data sets similarly showed
an independent association between HIV and an increased risk of heart attack
(HR = 1.58; 95% CI, 1.25-1.99).
Risk of heart attack was highest for
HIV-positive people with a low CD4 cell count (p = 0.04) and a detectable
viral load (p = 0.05). However, even participants with a viral load below 500
copies/ml had an increased risk of heart attack (HR = 1.39; 95% CI, 1.17-1.66).
The investigators then restricted their
analysis to the participants with HIV. A recent viral load above 500 copies/ml (HR
= 1.60; 95% CI, 1.14-2.22) and recent CD4 cell count below 200 cells/mm3
(HR = 1.57; 95% CI, 1.10-2.24) were both associated with heart attack.
Treatment with a protease inhibitor was of borderline significance (HR = 1.34;
95% CI, 0.98-1.81; p = 0.06) when included in a model that adjusted for
Framingham risk scores, co-infections and drug and alcohol use.
“Veterans with HIV infection have a
significantly higher risk of AMI compared with demographically and behaviorally
similar uninfected veterans even after adjusting for Framingham risk factors,
comorbidities and substance abuse,” comment the investigators. “Findings from
this and prior studies suggest that the increased risk of AMI among
HIV-positive people is likely a function of HIV, ART, and the burden of
comorbid disease including Framingham risk factors.”
However, the investigators emphasise that
the HIV-positive participants and controls had the same baseline Framingham risk
profiles. They therefore suggest that: “Framingham risk score may underestimate AMI
risk among HIV-positive people and that the addition of HIV and ART to a model
of established AMI risk factors may be clinically useful.”