Reduction in coronary and peripheral vasomotor function in patients with HIV after initiation of antiretroviral therapy: a longitudinal study with positron emission tomography and flow-mediated dilation

Coronary Microvascular Dysfunction Is Present Among Well-Treated Asymptomatic Persons With HIV and Similar to Those With Diabetes

Background

Coronary microvascular dysfunction (CMD) could be a potential underlying mechanism for myocardial disease in HIV.

Methods

Comparisons of coronary flow reserve corrected for heart rate-blood pressure product (CFRCOR) were made among people with HIV (PWH) with no known history of cardiovascular disease (CVD) or diabetes mellitus, persons without HIV (PWOH), and persons with diabetes (PWDM) and no known history of CVD or HIV.

Results

PWH (n = 39, 74% male, age 55 [7] years, body mass index [BMI] 32.3 (26.8-34.9) kg/m2, duration of antiretroviral therapy 13 [5] years, CD4+ count 754 [598-961] cells/μL) were similar to PWOH (n = 69, 74% male, age 55 [8] years, BMI 32.2[25.6-36.5] kg/m2) and PWDM (n = 63, 63% male, age 55 [8] years, BMI 31.5 [28.6-35.6] kg/m2). CFRCOR was different among groups: PWOH 2.76 (2.37-3.36), PWH 2.47 (1.92-2.93), and PWDM 2.31 (1.98-2.84); overall P = .003. CFRCOR was reduced comparing PWH to PWOH (P = .04) and PWDM to PWOH (P = .007) but did not differ when comparing PWH to PWDM (P = .98). A total 31% of PWH had CFRCOR < 2.0, a critical cutoff for CMD, compared to 14% of PWOH and 27% with PWDM. A total 40% of women with HIV had a CFRCOR < 2.0 compared to 6% of women without HIV (P = .02).

Conclusions

Subclinical CMD is present among chronically infected and well-treated, asymptomatic PWH who are immunologically controlled. This study demonstrates CFR is reduced in PWH compared to PWOH and comparable to PWDM, further highlighting that well-treated HIV infection is a CVD-risk enhancing factor for CMD similar to diabetes. Clinical Trials Registration: NCT02740179.

HIV Infection, Antiretroviral Drugs, and the Vascular Endothelium

Endothelial cell activation, injury, and dysfunction underlies the pathophysiology of vascular diseases and infections associated with vascular dysfunction, including human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome. Despite viral suppression with combination antiretroviral therapy (ART), people living with HIV (PLWH) are prone to many comorbidities, including neurological and neuropsychiatric complications, cardiovascular and metabolic diseases, premature aging, and malignancies. HIV and viral proteins can directly contribute to the development of these comorbidities. However, with the continued high prevalence of these comorbidities despite viral suppression, it is likely that ART or some antiretroviral (ARVs) drugs contribute to the development and persistence of comorbid diseases in PLWH. These comorbid diseases often involve vascular activation, injury, and dysfunction. The purpose of this manuscript is to review the current literature on ARVs and the vascular endothelium in PLWH, animal models, and in vitro studies. I also summarize evidence of an association or lack thereof between ARV drugs or drug classes and the protection or injury/dysfunction of the vascular endothelium and vascular diseases.

Endothelial dysfunction and cardiovascular diseases in people living with HIV on specific highly active antiretroviral therapy regimen: A systematic review of clinical studies

Despite the improved efficacy of highly active antiretroviral therapy (HAART) in viral suppression, emerging evidence indicates an increased burden of noncommunicable diseases in people living with HIV (PLWH). Immune activation and persistently elevated levels of inflammation have been associated with endothelial dysfunction in PLWH, likely contributing to the development of cardiovascular diseases (CVDs). Here, electronic search databases including PubMed, Google Scholar, Cochrane Library, and Science Direct were used to retrieve scientific evidence reporting on any association between markers of endothelial function and CVD-related outcomes in PLWH on HAART. Extracted data was subjected to quality assessment using the Downs and Black checklist. Most (60 %) of the results indicated the presence of endothelial dysfunction in PLWH on HAART, and this was mainly through reduced flow mediated dilation and elevated serum makers of adhesion molecules like ICAM-1, VCAM-1, and P-selectin. The summarized evidence indicates an association between persistently elevated markers of endothelial dysfunction and a pro-inflammatory state in PLWH on HAART. Only a few studies reported on improved endothelial function markers in PLWH on HAART, while limited evidence is available to prove that endothelial dysfunction is associated with CVD-risk, which could be attributed to therapeutic effects of HAART. Limited studies with relatively high quality of evidence were included in this systematic review. In conclusion, results from this review lay an important foundation for future research, even a meta-analysis, that will improve the understanding of the contributing factors to the burden of CVDs in PLWH on HAART.

Large lessons learned from small vessels: coronary microvascular dysfunction in HIV

PURPOSE OF REVIEW

Large cohort studies have consistently shown the presence of heart failure is approximately doubled among persons with HIV (PWH). Early studies of cardiovascular disease (CVD) in HIV were primarily focused on atherosclerotic burden, and we now have a greater understanding of large vessel disease in HIV. More recent studies have begun to inform us about small vessel disease, or coronary microvascular dysfunction (CMD), in HIV. CMD is recognized to be an important risk factor for adverse events related to heart failure, associated with cardiovascular mortality, and often presents without overt atherosclerotic disease.

RECENT FINDINGS

In this review, we highlight implications for CMD and relevant clinical studies in HIV. Inflammation and endothelial dysfunction, well known risk factors in HIV, may mediate the pathogenesis of CMD. Initial studies suggest that CMD worsens with ART initiation. Newer studies reveal CMD is present among well treated PWH without known CVD. In addition, myocardial flow reserve (MFR), a marker of CMD, is reduced in HIV similar to diabetes. There also appears to be sex differences, such that CMD is worse among women vs. men with HIV.

SUMMARY

Alterations in the coronary microvasculature may be an important mediator of subclinical myocardial dysfunction that deserves further clinical attention among PWH without known CVD.

Coronary Microcirculatory Dysfunction in People With HIV and Its Association With Antiretroviral Therapy

BACKGROUND

HIV infection and abacavir-containing antiretroviral regimens are associated with vascular endothelial dysfunction and increased cardiovascular risk. Positron emission tomography (PET)-derived myocardial blood flow reserve (MBFR), the ratio of vasodilator stress to rest myocardial blood flow, is a well-validated measure of coronary microvascular health and marker of cardiovascular risk. Our objective was to compare MBFR among people with HIV (PWH) with matched non-HIV controls and to assess whether switching from dolutegravir/lamivudine/abacavir to the non-abacavir regimen bictegravir/emtricitabine/tenofovir alafenamide (TAF) would improve MBFR.

METHODS AND RESULTS

Thirty-seven PWH were 1:2 matched on cardiovascular risk factors to 75 people without HIV, and MBFR corrected for differences in resting hemodynamics was compared in a cross-sectional design. PWH were majority men (68%) with a mean age of 56 years. Mean stress myocardial blood flow (1.83 mL/min per g [95% CI, 1.68-1.98] versus 2.40 mL/min per g [95% CI, 2.25-2.54]; P<0.001) and MBFR (2.18 [95% CI, 1.96-2.40] versus 2.68 [95% CI, 2.47-2.89]; P=0.002) was significantly lower in PWH than in people without HIV. In a single-arm, multicenter trial, a subset of 25 PWH who were virologically suppressed on dolutegravir/lamivudine/abacavir underwent positron emission tomography myocardial perfusion imaging at baseline and after switching to bictegravir/emtricitabine/TAF. MBFR was unchanged after switching to bictegravir/emtricitabine/TAF for a mean of 27 weeks (MBFR, 2.34 to 2.29; P=0.61), except in PWH with impaired MBFR at baseline (<2.00; N=6) in whom MBFR increased from 1.58 to 2.02 (P=0.02).

CONCLUSIONS

PWH had reduced coronary microvascular function compared with controls without HIV. Coronary microvascular function did not improve after switching from dolutegravir/lamivudine/abacavir to bictegravir/emtricitabine/TAF.

REGISTRATION

URL: https://www.clinicaltrials.gov; unique identifier: NCT03656783.

Imaging modalities for cardiovascular phenotyping in asymptomatic people living with HIV

Cardiovascular disease (CVD) has emerged as a leading cause of non-HIV-related mortality among people living with HIV (PLWH). Despite the growing CVD burden in PLWH, there is concern that general population risk score models may underestimate CVD risk in these patients. Imaging modalities have received mounting attention lately to better understand the pathophysiology of subclinical CVD and provide improved risk assessment in this population. To date, traditional and well-established techniques such as echocardiography, pulse wave velocity, and carotid intima thickness continue to be the basis for the diagnosis and subsequent monitoring of vascular atherosclerosis and heart failure. Furthermore, novel imaging tools such as cardiac computed tomography (CT) and cardiac CT angiography (CCTA), positron emission tomography/CT (PET/CT), and cardiac magnetic resonance (CMR) have provided new insights into accelerated cardiovascular abnormalities in PLWH and are currently evaluated with regards to their potential to improve risk stratification.

HIV infection, antiretroviral therapy, and measures of endothelial function, inflammation, metabolism, and oxidative stress

Background

HIV-infected patients have an increased risk of cardiovascular disease (CVD). Impaired endothelial function is an early risk factor for CVD in the general population. It is presumed that HIV infection is associated with impaired endothelial function, but results have been inconsistent.

Objectives

Our objectives were to determine the relationships between HIV infection, virologic suppression with antiretroviral therapy (ART), in vivo measures of conduit artery and microvascular endothelial function, and circulating biomarkers of pathways associated with CVD.

Methods

We performed a cross-sectional analysis of three prospectively enrolled groups from a single center: 28 were HIV-infected and virologically-suppressed on a regimen of FTC/TDF/EFV (HIV+ART+), 44 were HIV-infected but not on ART (HIV+ART-), and 39 were HIV-uninfected healthy volunteers (HIV-) matched to the HIV+ART- group for age, sex, smoking status, and height. None had diabetes, uncontrolled hypertension, known CVD, or other pro-inflammatory condition. Flow mediated dilation (FMD), nitroglycerin-mediated dilation (NTGMD), reactive hyperemia velocity time integral (RHVTI), and FMD/RHVTI of the brachial artery were measured, as well as circulating biomarkers of systemic inflammation, metabolism, oxidative stress, and endothelial activation.

Results

No significant differences were found amongst the three groups in FMD (P = 0.46), NTGMD (P = 0.42), RHVTI (P = 0.17), and FMD/RHVTI (P = 0.22) in unadjusted comparisons. Adjusted ANOVA models which included brachial artery diameter, demographics, and conventional CVD risk factors did not appreciably change these findings. In pairwise comparisons, the HIV+ART- group had significantly higher soluble tumor necrosis factor receptor II, soluble CD163, β-2 microglobulin, interferon-γ- induced protein-10, tissue inhibitor of metalloproteinase-1, and vascular cell adhesion molecule-1 compared to the other two groups (all p<0.05). Correlates of endothelial function differed between study groups.

Conclusion

Although untreated HIV infection was associated with elevated levels of several biomarkers of inflammation and endothelial activation, we were unable to demonstrate differences in measures of conduit artery and microvascular endothelial function in this study population.

Coronary artery endothelial dysfunction is present in HIV-positive individuals without significant coronary artery disease

OBJECTIVE

HIV-positive (HIV+) individuals experience an increased burden of coronary artery disease (CAD) not adequately accounted for by traditional CAD risk factors. Coronary endothelial function (CEF), a barometer of vascular health, is depressed early in atherosclerosis and predict future events but has not been studied in HIV+ individuals. We tested whether CEF is impaired in HIV+ patients without CAD as compared with an HIV-negative (HIV-) population matched for cardiac risk factors.

DESIGN/METHODS

In this observational study, CEF was measured noninvasively by quantifying isometric handgrip exercise-induced changes in coronary vasoreactivity with MRI in 18 participants with HIV but no CAD (HIV+CAD-, based on prior imaging), 36 age-matched and cardiac risk factor-matched healthy participants with neither HIV nor CAD (HIV-CAD-), 41 patients with no HIV but with known CAD (HIV-CAD+), and 17 patients with both HIV and CAD (HIV+CAD+).

RESULTS

CEF was significantly depressed in HIV+CAD- patients as compared with that of risk-factor-matched HIV-CAD- patients (P < 0.0001) and was depressed to the level of that in HIV- participants with established CAD. Mean IL-6 levels were higher in HIV+ participants (P < 0.0001) and inversely related to CEF in the HIV+ patients (P = 0.007).

CONCLUSION

Marked coronary endothelial dysfunction is present in HIV+ patients without significant CAD and is as severe as that in clinical CAD patients. Furthermore, endothelial dysfunction appears inversely related to the degree of inflammation in HIV+ patients as measured by IL-6. CEF testing in HIV+ patients may be useful for assessing cardiovascular risk and testing new CAD treatment strategies, including those targeting inflammation.

Normal Myocardial Flow Reserve in HIV-Infected Patients on Stable Antiretroviral Therapy: A Cross-Sectional Study Using Rubidium-82 PET/CT

Studies have found HIV-infected patients to be at increased risk of myocardial infarction, which may be caused by coronary microvascular dysfunction. For the first time among HIV-infected patients, we assessed the myocardial flow reserve (MFR) by Rubidium-82 (82Rb) positron emission tomography (PET), which can quantify the coronary microvascular function. MFR has proved highly predictive of future coronary artery disease and cardiovascular events in the general population.In a prospective cross-sectional study, HIV-infected patients all receiving antiretroviral therapy (ART) with full viral suppression and HIV-uninfected controls were scanned using 82Rb PET/computed tomography at rest and adenosine-induced stress, thereby obtaining the MFR (stress flow/rest flow), stratified into low ≤1.5, borderline >1.5 to 2.0, or normal >2.0.Fifty-six HIV-infected patients and 25 controls were included. The HIV-infected patients had a mean age of 53 years (range 37-68 years) with 23% active smokers. The controls had a mean age of 52 years (range 36-68 years) and 26% active smokers. In the HIV-infected group 73% had a normal MFR, 17% borderline, and 10% low values of MFR. Among controls these values were 71%, 19%, and 10%, respectively (P = 0.99). However, the HIV-infected group had lower values of stress myocardial blood flow (MBF) (2.63 ± 0.09 mL/g/min vs 2.99 ± 0.14 mL/g/min; P = 0.03). We found no evidence of decreased MFR as assessed by 82Rb PET among HIV-infected patients on stable ART with full viral suppression compared with HIV-uninfected controls. We did notice a decreased MBF during stress.

A randomized, controlled trial of the effect of rilpivirine versus efavirenz on cardiovascular risk in healthy volunteers

OBJECTIVES

The HIV NNRTI rilpivirine is being evaluated as a possible agent for HIV pre-exposure prophylaxis. We have recently shown that the NNRTI efavirenz may impair endothelial function assessed as flow-mediated dilation (FMD), but whether this impairment is also found with rilpivirine is unknown. We sought to compare cardiovascular risk profiles between efavirenz and rilpivirine in healthy volunteers.

METHODS

We performed a prospective, randomized, open-label trial in 40 HIV-uninfected healthy volunteers who were randomized 1: 1 to either efavirenz or rilpivirine. Vascular indices, metabolic parameters, inflammatory biomarkers and oxidative stress were measured before and after 4 weeks of treatment. This study is registered at ClinicalTrials.gov (NCT01585038).

RESULTS

There were no significant differences in 4 week mean (SD) changes in FMD between efavirenz and rilpivirine [0.089 (3.65)% versus 0.63 (2.42)%; P = 0.77]. There were also no significant differences in 4 week changes in high-sensitivity C-reactive protein, IL-6, soluble vascular cell adhesion molecule-1, HDL-cholesterol, triglycerides or homeostasis model assessment-insulin resistance. However, efavirenz led to significant increases in total cholesterol [19.39 (23.9) versus -5.78 (16.5) mg/dL; P < 0.001], LDL-cholesterol [13.29 (19.5) versus -2.24 (13.4) mg/dL; P = 0.009] and F2-isoprostanes [92.7 (178.6) versus -101.4 (215.7) pg/mL; P = 0.019] compared with rilpivirine. Two participants from each study group discontinued prematurely for adverse events.

CONCLUSIONS

There were no significant differences in the changes in endothelial function over 1 month between the efavirenz and rilpivirine groups, although efavirenz had worse lipid changes compared with rilpivirine. Longer-term studies are required for confirmation.

HIV infection and arterial inflammation assessed by (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET): a prospective cross-sectional study

BACKGROUND

HIV-infected patients are at increased risk of myocardial infarction and arterial inflammation has been suggested as a pathophysiological explanation. We compared the uptake of (18)F-fluorodeoxyglucose (FDG) by PET in four arterial regions, and factors associated with FDG uptake in well-treated HIV-infected patients without cardiovascular disease (CVD) and healthy controls.

METHODS AND RESULTS

We prospectively scanned 26 HIV-infected patients on stable antiretroviral therapy and 25 healthy volunteers with FDG PET/CT, measuring standardized uptake values (SUV) in the carotid arteries, the ascending, descending, and abdominal aorta. We performed correlation analyses between FDG uptake and intima-media thickness (IMT), and soluble biomarkers of inflammation. We found no difference in arterial FDG uptake between the HIV-infected patients and healthy controls quantified either as mean SUVmax or target-to background ratio in the carotid region, the ascending aorta, the descending aorta, or the abdominal aorta. Correlations between SUV, IMT, and soluble biomarkers were scarce in both groups.

CONCLUSION

In a group of optimally treated HIV-infected patients with full viral suppression, low Framingham risk score and no known CVD, we found no evidence of increased arterial inflammation as assessed by FDG PET/CT compared to healthy volunteers.

Effects of switching from efavirenz to raltegravir on endothelial function, bone mineral metabolism, inflammation, and renal function: a randomized, controlled trial

We performed a randomized controlled trial in 30 HIV-infected participants to either continue tenofovir/emtricitabine/efavirenz (Continuation Group) or switch to tenofovir/emtricitabine/raltegravir (Switch Group) for 24 weeks. There were no significant differences in the changes in flow-mediated dilation, 25(OH) vitamin D, or parathyroid hormone levels. Total cholesterol, high sensitivity C-reactive protein, serum alkaline phosphatase, sCD14 levels, and renal function significantly declined in the Switch Group compared with the Continuation Group; however, sCD163 levels significantly increased in the Switch Group. These findings suggest that raltegravir is not inherently more beneficial to endothelial function compared with efavirenz but may impact renal function and monocyte activation.

Review: comparison of PET rubidium-82 with conventional SPECT myocardial perfusion imaging

Nuclear cardiology has for many years been focused on gamma camera technology. With ever improving cameras and software applications, this modality has developed into an important assessment tool for ischaemic heart disease. However, the development of new perfusion tracers has been scarce. While cardiac positron emission tomography (PET) so far largely has been limited to centres with on-site cyclotron, recent developments with generator produced perfusion tracers such as rubidium-82, as well as an increasing number of PET scanners installed, may enable a larger patient flow that may supersede that of gamma camera myocardial perfusion imaging.

Cardiovascular disease in patients with HIV

The introduction of combination antiretroviral therapy (cART) has substantially decreased mortality among the HIV-infected population. In this setting, cardiovascular disease (CVD) has become a leading cause of morbidity and mortality. Compared with the general population, higher rates of myocardial infarction as well as a high prevalence of subclinical coronary atherosclerosis have been found in the HIV-infected population. It has been suggested that in HIV-infected patients, the atherosclerotic burden is not based solely on traditional cardiovascular risk factors. The interplay of other mechanisms such as chronic inflammation, effects of cART or immune activation after initiation of cART may predispose to accelerated and increased risk of CVD. Effective treatment are available today to reduce CVD in at-risk patients, and therefore early detection of subclinical coronary atherosclerosis is important. However, the mechanisms behind the development of CVD in HIV-infected patients may limit the usefulness of the traditional noninvasive screening tools for CVD used in the general population. This review will focus on the different plausible mechanisms behind the increased risk of CVD and the noninvasive methods by which atherosclerosis may be assessed in the HIV-infected population.

Imaging atherosclerosis in HIV: carotid intima-media thickness and beyond

Chronic immune activation and inflammation are associated with an increased risk of atherosclerosis in HIV-infected patients. In this review, we discuss the role of established and novel imaging modalities to define more accurately the structure and function of inflammation-mediated atherosclerosis in the context of HIV. Historically, carotid ultrasound studies were the first to show higher rates of subclinical atherosclerosis in HIV-infected subjects versus uninfected controls. However, computed tomography is the noninvasive gold standard for imaging the coronary arteries, and studies in HIV suggest a higher prevalence of noncalcified plaque. Endothelial dysfunction can be quantified by measuring flow-mediated brachial artery dilation by ultrasound and has been used extensively in antiretroviral switching trials and small pilot trials of therapeutics to assess cardiovascular risk in this population. In the future, novel imaging modalities such as intracoronary optical coherence tomography, positron emission tomography imaging of (18)F-fluorodeoxyglucose uptake, and molecular-targeted magnetic resonance imaging will characterize the burden of vulnerable plaque and other unique features of inflammatory atherosclerosis in HIV.

Cardiovascular implications of HIV-induced dyslipidemia

Cardiovascular disease (CVD) is currently the second most frequent cause of death (after cancer) among HIV-positive subjects. The clinical use of highly active antiretroviral therapy (HAART) has dramatically reduced mortality and morbidity in HIV-positive population, leading to prolonged and improved quality of life. However, as mortality and morbidity from AIDS-related conditions improve, CVD assumes increasing magnitude. It is estimated that by 2015 more than 50% of HIV-positive patients will be older than 50 years. Since age is a major unmodifiable cardiovascular risk factor, the risk for CVD in this population will significantly and progressively increase in the near future. A large part of the risk for cardiovascular events appears to be a result of lipid abnormalities characterizing HIV-positive persons. This review focuses on HIV-associated lipid abnormalities and CVD. Lipid abnormalities may be related to either viral infection, HAART or both. Dyslipidemia characterizing HIV-infected patients has become a therapeutic target to reduce cardiovascular risk of HIV-treated patients. HAART-treated patients show an atherogenic lipid profile comprised of low HDL-cholesterol levels, hypertrigliceridemia and increased levels of small-LDL particles. Current guidelines for the treatment of dyslipidemia and reducing cardiovascular risk in HIV-positive patients suggest that when lifestyle modifications (i.e., diet and exercise) and switching antiretroviral therapy are not enough, statins should be the first-line therapy for dyslipidemia. HDL raising interventions (niacin and fibrates) should be considered to raise HDL levels and lower triglyceride in HIV-infected patients. Implications of lipid-related interventions in HIV-treated patients to avoid drug interactions and their adverse effects are also discussed.