Longer duration of infection with HIV linked with hardening of coronary arteries

Using CT scans, US investigators have found that young men with HIV are significantly more likely than their HIV-negative peers to have hardening of the arteries. In a study published in the on-line edition of AIDS the researchers also found that arterial disease was so severe in 7% of men with HIV that it was blocking blood flow. Longer duration of HIV infection was the most important risk factor for hardening of the coronary arteries.

“The current study shows an increased prevalence and greater degree of subclinical coronary artery disease in asymptomatic young HIV-infected men without prior history of cardiovascular disease”, write the investigators.

Antiretroviral therapy can significantly extend the life expectancy of individuals with HIV. Although AIDS-related illnesses are now rare in patients taking HIV treatment, there is evidence that individuals with HIV have an increased risk of developing a number of diseases of ageing, including cardiovascular disease.

HIV infection itself and a higher prevalence of traditional risk factors for cardiovascular disease in the HIV-positive population are possible causes.

Prompt detection of cardiovascular disease can mean that individuals can be provided with appropriate treatment.

Coronary computed tomography (CT) angiography (a scan of the coronary arteries) is an accurate way of measuring asymptomatic hardening of the coronary arteries. It can also show how many plaques have formed in the arteries and their volume.

Investigators in the US therefore performed CT angiographs on 78 HIV-positive men and 32 HIV-negative controls to see if infection with HIV increased the risk of hardening of the arteries.

The HIV-positive men were all asymptomatic and none of the men in the study had a history of either heart or kidney disease.

The average duration of HIV infection was 14 years and 95% of the HIV-infected individuals were taking antiretroviral therapy. Median CD4 cell count was normal at 523 cells/mm³ and 81% had an undetectable viral load.

There were no significant differences in the prevalence of traditional risk factors for cardiovascular disease between the HIV-positive and HIV-negative men. Age, family history of heart disease, blood pressure, cholesterol and Framingham risk scores (ten year risk of heart disease) were comparable between the two groups.

Nevertheless, there was a significant difference in the prevalence of hardening of the coronary arteries between the HIV-positive and HIV-negative men. In total, 59% of those with HIV had arteriosclerosis compared to 34% of HIV-negative men (p = 0.02). This difference remained significant after controlling for traditional risk factors for cardiovascular disease (p = 0.02).

Moreover individuals with HIV had a higher number of arterial plaques (1 vs. O, p = 0.03) and a higher plaque volume (p = 0.02).

Patients with HIV also had higher arterial calcium scores, and 7% of those with HIV compared to none of the individuals without HIV had coronary stenosis (narrowing of the arteries) that was greater than 70%.

The investigators then restricted their analysis to the HIV-positive men.

Those with plaques detected by CT scans of the heart were older (p = 0.04), had been infected with HIV for longer (p = 0.02), had a higher Framingham score (p = 0.002), higher cholesterol (p = 0.04), higher triglycerides (p = 0.04) and a lower CD4/CD8 ratio (p = 0.001).

Both traditional and HIV-related risk-factors were associated with total number of plaques (age, Framingham score, duration of HIV infection, duration of treatment with a protease inhibitor, cholesterol and CD4/CD8 ratio).

After controlling for age and Framingham risk score, the duration of HIV infection remained significantly associated with both the number of plaques (p = 0.04) and plaque volume (p = 0.05).

The duration of HIV-infection’s association remained significant even when the investigators controlled for duration of treatment with a protease inhibitor, and lipids (p = 0.047), and for other HIV-related factors including CD4 cell count, viral load, and duration of antiretroviral therapy (p = 0.007).

“The prevalence of coronary artery disease in HIV-infected patients was significantly greater than that seen in…HIV-seronegative men with similar demographics, Framingham risk scores, and traditional risk factors”, note the investigators.

They add, “surprisingly and of important clinical relevance, even among asymptomatic young HIV-infected men, 6.5% had evidence of severe coronary arterial disease…in contrast, one of the controls had severe obstructive coronary arterial disease.”

Findings of the study look likely to contribute to the debate on why individual with HIV have an increased risk of heart disease. The investigators comment, “our data…support the hypothesis that there is a relationship between HIV infection and coronary artery atherosclerosis independent of traditional risk factors as [these] were generally similar between the two groups.”

Duration of HIV infection had a “significant and robust” relationship with hardening of the coronary artery.

“Our data highlight the need to address cardiac risk reduction early on in the course of HIV disease”, conclude the researchers.