Exercise-induced PH Linked to Cardiovascular Risk in HIV Patients

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Pulmonary hypertension (PH) induced in response to exercise may be linked to a higher risk of cardiovascular (CV) disease in patients with human immunodeficiency virus (HIV), a small study found.

Those with a higher CV risk had fewer CD4 T-cells, a type of immune cell that drops to extremely low numbers in acquired immunodeficiency syndrome (AIDS), the disease caused by HIV. They also had a faster progression to AIDS and a poorer response to antiretroviral medications that inhibit the ability of HIV to multiply in the body.

These patients’ lungs had significantly higher pulmonary vascular resistance, meaning the blood had to push harder to flow through the blood vessels. These patients’ right upper (atrial) chamber of the heart was larger, which occurs when it has to pump blood harder than usual.

The findings suggest an evaluation for exercise-induced PH may help identify those who are most at risk of diseases of the heart and the blood vessels.

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The study, “Exercise-induced pulmonary hypertension is associated with high cardiovascular risk in patients with HIV,” was published in the Journal of Clinical Medicine by a team of researchers in Italy.

Exercise-induced PH is linked with poor control of HIV infection and more difficulty with daily tasks in those with HIV. This may happen because worsening lung disease may limit how far the blood vessels can stretch to let blood flow from the heart to the lungs, causing an unusually high pressure to build up. This is relevant because “PH at rest can be preceded by the onset of exercise-induced PH,” the researchers wrote.

The high pressure also places a strain on the heart, which has to pump blood harder than usual, causing it to become larger and weaker with time. How exercise-induced PH may be linked to the risk of CV disease is unknown.

The researchers recruited 54 patients who tested positive for HIV from the Infectious Disease Clinic at Pisa University Hospital. Eight were highly likely to have PH at rest and were excluded. Of the remaining 46 patients, 43 had a low and three had an intermediate chance of having PH at rest. There were 30 men and 16 women, and their mean age was 53.

To make a diagnosis of exercise-induced PH, the researchers used the cardiopulmonary exercise test (CPET) and exercise stress echocardiogram (ESE). These measure how well the lungs and heart work in response to stress or exercise. They found that 13 (28%) patients had exercise-induced PH based on the results of both tests. They also found a good agreement between the two tests, as assessed by a statistical analysis.

Patients with exercise-induced PH had significantly worse functional capacity, higher pulmonary vascular resistance and pulmonary arterial pressure, and a larger right atrium than those without exercise-induced PH.

The researchers also looked at certain factors known to predict the risk of developing CV disease. Based on these factors, they calculated the CV risk score, which ranged from 8 (low risk) to 14 (high risk). The average was 10.2.

They also found that participants with exercise-induced PH had a CV risk score that was about four points higher than those without exercise-induced PH.

Having a higher CV risk score was linked to fewer CD4 T-cells, faster progression to AIDS, and a poorer response to antiretroviral medications. It was also linked to higher pulmonary vascular resistance at rest and a larger right atrium.

While the number of patients in the study was small, the findings suggest that “using the combined ESE and CPET approach allows for the identification of those patients with HIV who develop [exercise-induced PH] due to reduced pulmonary vasodilatory reserve and who have a worse CV risk profile,” the researchers said.