Elevated blood pressure is associated with an increased risk of heart attack among people with HIV, a US study published in the online edition of Clinical Infectious Diseases shows. However, investigators from the Veterans Aging Study Virtual Cohort also found that, in most cases, people living with HIV who had elevated blood pressure had a similar risk of heart attack when compared with HIV-negative controls with similar elevations in blood pressure.
“HIV status and blood pressure are associated with AMI [acute myocardial infarction (heart attack)] risk independently of each other,” comment the authors. “By comparing all participants to a common referent group…we were better able to assess the individual and combined effects of HIV status on elevated blood pressure.”
There is now a large body of research showing that people living with HIV have an increased risk of heart attack compared to HIV-negative individuals. Elevated blood pressure – hypertension and prehypertension – are recognised risk factors for heart attack in the general population. Blood pressure control is as important for people with HIV as anyone else. Current goals for blood pressure control are below 140/90 mmgHg (hypertension) or below 130/80 mmHg (prehypertension).
Investigators wanted to see if people with HIV who have elevated blood pressure had an increased risk of heart attack over and above that seen in matched HIV-negative controls.
Their study population comprised 81,000 US veterans who received care after 2003. A third of participants in the study were living with HIV and each participant was matched with two HIV-negative controls of the same age and ethnicity.
Blood pressure was assessed at baseline. In people not taking blood pressure treatment, it was categorised as normal if between 90-120/60-80 mmHg (16%); prehypertensive when between 120-139/80-89 mmHg (44%) and hypertensive when 140/100 mmHg or above (39%). There were similar proportions of people with HIV and HIV-negative people in each blood pressure category. Mean age ranged from 46 to 53 years.
The participants in the study were followed for a median of 5.9 years and contributed a total of 406,000 person-years of follow-up. During this time there were 860 heart attacks.
The incidence of heart attack increased as blood pressure increased, and was 12.9 per 10,000 person-years among people with normal blood pressure compared to 14.5 per 10,000 person-years for people with hypertension.
People living with HIV who had normal blood pressure or prehypertension did not have an increased risk of heart attack compared to the HIV-negative controls. However, the risk of heart attack was significantly higher among people living with HIV who were hypertensive compared to control patients with hypertension (aHR = 2.57; 95% CI, 1.76-3.76 vs. aHR = 1.47; 95% CI, 1.02-2.11).
Despite this there was no significant interaction between elevated blood pressure and HIV status and the risk of heart attack in a statistical model that considered blood pressure as a continuous measure.
“We found no statistical interaction between HIV, elevated blood pressure and AMI risk,” the investigators write. “This suggests that HIV may not modify the association between blood pressure and AMI risk.”
Compared to HIV-negative individuals with normal blood pressure, people living with HIV who had prehypertension or hypertension had a significant increase in the risk of heart attack.
Each 10 mmg/Hg increase in pulse pressure was associated with a small but significant increase in the risk of heart attack (HR = 1.12; 95% CI, 1.06-1.19). Having HIV did not modify the association between pulse pressure and heart attack risk.
“Our data suggest that traditional CVD [cardiovascular disease] risk factors like hypertension contribute additional AMI risk independently of and in addition to that contributed by HIV infection,” comment the researchers. They acknowledge a number of limitations in their study, including its observational design, statistical power and the possibility of unmeasured confounding, such as family history.
“Prehypertensive and hypertensive blood pressure was associated with an increased risk of AMI in a cohort of HIV infected and uninfected Veterans,” the authors conclude. “Future studies should prospectively investigate whether HIV interacts with blood pressure to further increase AMI risk.”
Armah KA et al. Prehypertension, hypertension and the risk of acute myocardial infarction in HIV infected and uninfected veterans. Clin Infect Dis, online edition, 2013.