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

Advances in the Management of Cardiovascular Disease in the Setting of Human Immunodeficiency Virus

This state-of-the art review discusses the underlying mechanisms that contribute to atherosclerotic cardiovascular disease, heart failure and arrhythmias among people with human immunodeficiency virus (HIV), risk prediction and prevention, management, and outstanding research questions, including a discussion of how the Randomized Trial to Prevent Vascular Events in HIV may inform clinical practice.

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.

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.

Myocardial perfusion reserve in patients with chronic hepatitis C before and after direct-acting antiviral treatment-a pilot study

INTRODUCTION

Patients with chronic hepatitis C (CHC) have an increased risk of atherosclerotic cardiovascular disease which may be due to inflammation and endothelial dysfunction caused by the chronic infection. In this prospective pilot study, we assessed, for the first time among patients with CHC the myocardial perfusion reserve (MPR) by Rubidium-82 (⁸² Rb) positron emission tomography (PET)/computed tomography (CT) before and after direct-acting antiviral (DAA) treatment and compared them with biomarkers of systemic inflammation and endothelial dysfunction.

METHODS

We included 10 patients with CHC who received 8 or 12 weeks of DAA treatment. To obtain the MPR, a cardiac ⁸² Rb PET/CT scan at rest and adenosine-induced stress was performed at baseline and between 12 and 24 weeks post DAA treatment. Additionally, markers of endothelial dysfunction and inflammation were measured at baseline and 12 weeks after DAA treatment.

RESULTS

All 10 patients achieved cure and the median age was 50 (range: 40-62 years). The median MPR before treatment was 3.1 (range: 2.3-4.8) compared to 2.9 (range: 2.2-4.1) after DAA treatment p = 0.63. Also, cure after DAA treatment was not associated with an overall significant decrease in markers of endothelial dysfunction and inflammation.

DISCUSSION

Cure after DAA treatment in patients with CHC did not improve coronary microvascular function nor did it lead to a decrease in soluble markers of cardiovascular risk in the given time frame where the patients were followed. It should be noted, that MPR before DAA treatment was in the normal range. Considering the small sample size and short follow-up time, further studies are warranted to determine if viral clearance has an effect on coronary microvascular function and endothelial dysfunction.

Cardiovascular disease risk in women living with HIV

PURPOSE OF REVIEW

To synthesize current evidence on the impact of cardiovascular disease among women living with HIV (WLWH) with a particular focus on disease prevalence, mechanisms and prevention.

RECENT FINDINGS

HIV-related cardiovascular disease risk is 1.5-fold to 2-fold higher for women than for men. Mechanisms of enhanced risk are multifactorial and include reinforcing pathways between traditional risk factors, metabolic dysregulation, early reproductive aging and chronic immune activation. These pathways influence both the presentation of overt syndromes of myocardial infarction, stroke and heart failure, as well as subclinical disease, such as microvascular dysfunction and cardiac fibrosis. Cardiovascular disease, therefore, remains a consistent threat to healthy aging among WLWH.

SUMMARY

Although no specific prevention strategies exist, patient-centered risk mitigation approaches that are adaptable to the needs of aging individuals are essential to combat disparities in cardiovascular outcomes among WLWH. Further research into the optimal prevention approach for CVD among WLWH, particularly for women living in under-resourced health systems, is needed.

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.

Rubidium-82 positron emission tomography for detection of acute doxorubicin-induced cardiac effects in lymphoma patients

BACKGROUND

Doxorubicin is a cornerstone in lymphoma treatment, but is limited by dose-dependent cardiotoxicity. Rubidium-82 positron emission tomography (82Rb PET) assesses coronary microvascular function through absolute quantification of myocardial perfusion and myocardial perfusion reserve (MPR). Doxorubicin-induced microvascular injury represents a potential early marker of cardiotoxicity.

METHODS AND RESULTS

We included 70 lymphoma patients scheduled for doxorubicin-based treatment. Cardiotoxicity was evaluated with 82Rb PET myocardial perfusion imaging during rest and adenosine stress before chemotherapy and shortly after the first doxorubicin exposure. Patients with a MPR decline > 20% were defined as having a low threshold for cardiotoxicity. In the 54 patients with complete data sets, MPR was significantly lower after the initial doxorubicin exposure (2.69 vs 2.51, P = .03). We registered a non-significant decline in stress perfusion (3.18 vs 3.02 ml/g/min, P = .08), but no change in resting myocardial perfusion. There were 13 patients with a low cardiotoxic threshold. These patients had a significantly higher age, but were otherwise similar to the remaining part of the study population.

CONCLUSION

Decreases in MPR after initial doxorubicin exposure in lymphoma patients may represent an early marker of doxorubicin-induced cardiotoxicity. The prognostic value of acute doxorubicin-induced changes in MPR remains to be investigated.

Seeing Is Believing: Nuclear Imaging of HIV Persistence

A major obstacle to HIV eradication is the presence of infected cells that persist despite suppressive antiretroviral therapy (ART). HIV largely resides outside of the peripheral circulation, and thus, numerous anatomical and lymphoid compartments that have the capacity to harbor HIV are inaccessible to routine sampling. As a result, there is a limited understanding of the tissue burden of HIV infection or anatomical distribution of HIV transcriptional and translational activity. Novel, non-invasive, in vivo methods are urgently needed to address this fundamental gap in knowledge. In this review, we discuss past and current nuclear imaging approaches that have been applied to HIV infection with an emphasis on current strategies to implement positron emission tomography (PET)-based imaging to directly visualize and characterize whole-body HIV burden. These imaging approaches have various limitations, such as the potential for limited PET sensitivity and specificity in the setting of ART suppression or low viral burden. However, recent advances in high-sensitivity, total-body PET imaging platforms and development of new radiotracer technologies that may enhance anatomical penetration of target-specific tracer molecules are discussed. Potential strategies to image non-viral markers of HIV tissue burden or focal immune perturbation are also addressed. Overall, emerging nuclear imaging techniques and platforms may play an important role in the development of novel therapeutic and HIV reservoir eradication strategies.

Noninvasive Cardiovascular Imaging: Emergence of a Powerful Tool for Early Identification of Cardiovascular Risk in People Living With HIV

Antiretroviral therapy (ART) has been pivotal in prolonging the lifespan of people living with HIV (PLWH). However, this also simultaneously increases their risk of cardiovascular disease (CVD) either related to ART, aging, hypertension, immunosenescence, inflammation, immune activation, or other comorbidities. Although the use of risk markers has greatly enhanced the field of cardiovascular (CV) medicine and improved the prognosis and early diagnosis in the general population, this strategy has not been clearly elucidated in PLWH. Developing accurate risk algorithms for PLWH requires an innate understanding of mechanistic factors influencing their risks. Early identification of CV risk will significantly enhance the prospects of PLWH living longer and relatively healthily. Herein, we discuss the use of multimodality noninvasive CV imaging as robust markers for ameliorating CV risk. The ability to prognosticate CV risk and hence prevent CV events in PLWH would represent an important advance in CV medicine, allowing precise detection and early institution of preventative strategies. Using novel CV imaging modalities and strategies would have a positive impact on precision medicine in this patient cohort.

Cardiac Microvascular Dysfunction in Women Living With HIV Is Associated With Cytomegalovirus Immunoglobulin G

Background

People living with HIV (PLWH) appear to be at increased risk of cardiovascular disease (CVD), and this is possibly more pronounced in women living with HIV (WLWH). In the general population, men are more likely to develop obstructive coronary artery disease (CAD), and women often present with a nonobstructive pattern with cardiac microvascular dysfunction. We investigated cardiac microvascular function in men and women living with HIV and tested for association with cytomegalovirus (CMV) immunoglobulin G (IgG), as this has been associated with CVD in PLWH.

Methods

In a cross-sectional study, 94 PLWH on antiretroviral therapy were scanned with ⁸²Rb positron emission tomography/computed tomography at rest and during adenosine-induced stress, which enables the quantification of the myocardial flow reserve (MFR). CMV IgG was measured in plasma.

Results

WLWH had significantly lower MFR compared with men living with HIV (MLWH; P = .003), and >45% of the women had an MFR indicative of cardiac microvascular dysfunction, whereas this was only true for 24% of men (P = .03). CMV IgG concentrations were inversely associated with MFR among WLWH but not MLWH (P = .05 for interaction).

Conclusions

In this first study comparing MFR in women and men living with HIV, we found that WLWH had significantly lower MFR than MLWH and 45% of the women had cardiac microvascular dysfunction despite younger age and lower cardiovascular risk. Furthermore, CMV IgG was inversely associated with MFR among women but not men. This calls for attention to CVD among young WLWH even with low cardiovascular risk.

The hidden risk: Incorporating inflammation and HIV serostatus into coronary artery disease screening

CAD is a well-established comorbidity associated with HIV infection. This association is in large part due to ongoing inflammation propagated by viremia and dysregulation of the immune system. Despite this knowledge, evidence to guide clinical management and screening for CAD among HIV-infected patients is lacking. The following editorial discusses recent evidence that HIV-infected patients with abnormal cardiovascular stress testing are more likely to undergo subsequent percutaneous coronary intervention. Importantly, the cardiovascular consequences of HIV infection and potential clinical implications are discussed.

Comparison of the Peripheral Reactive Hyperemia Index with Myocardial Perfusion Reserve by 82Rb PET/CT in HIV-Infected Patients

After the introduction of antiretroviral therapy (ART) the life expectancy of patients infected with human immunodeficiency virus (HIV) is now approaching that of the general population and the importance of non-AIDS co-morbidities is increasing. Specifically, the risk of coronary artery disease (CAD) seems to be higher in HIV-infected patients and an accurate risk prediction of CAD is of high importance for optimal long term treatment. In this study, we assessed the correlation of the endoPAT, which is an office-based CVD screening tool with the myocardial perfusion reserve by ⁸²-rubidium PET/CT. We measured the reactive hyperemia index, which is a measure of the endothelial responsiveness, by the use of an endoPAT device (Itamar Medical, Caesarea, Israel) in 48 ART treated HIV-infected patients with high CD 4 cell counts and viral suppression (HIV-RNA < 20 copies/mL), who had previously undergone measurement of the myocardial perfusion reserve by ⁸²-rubidium PET/CT for study purposes. We found an inverse correlation between the reactive hyperemia index and the myocardial perfusion reserve which most likely indicates different vascular physiology. This study did not find evidence to suggest the immediate implementation of the reactive hyperemia index as a screening tool for early coronary artery disease in well-treated HIV-infected patients pending further validation in larger prospective studies.

Updates on Stress Imaging Testing and Myocardial Viability With Advanced Imaging Modalities

OPINION STATEMENT

Non-invasive stress testing plays a key role in diagnosis and risk stratification in patients with coronary artery disease. Technical advances in CT, MRI, and PET have lead to increased utility of these modalities in myocardial perfusion imaging. The aim of the review is to provide a succinct update on CT, PET, and MRI for myocardial stress perfusion imaging.

What happens to cardiovascular system behind the undetectable level of HIV viremia?

Despite the combined antiretroviral therapy has improved the length and quality of life of HIV infected patients, the survival of these patients is always decreased compared with the general population. This is the consequence of non-infectious illnesses including cardio vascular diseases. In fact large studies have indicated an increased risk of coronary atherosclerotic disease, myocardial infarction even in HIV patients on cART. In HIV infected patients several factors may contribute to the pathogenesis of cardiovascular problems: life-style, metabolic parameters, genetic predisposition, viral factors, immune activation, chronic inflammation and side effects of antiretroviral therapy. The same factors may also contribute to complicate the clinical management of these patients. Therefore, treatment of these non-infectious illnesses in HIV infected population is an emerging challenge for physicians. The purpose of this review is to focus on the new insights in non AIDS-related cardiovascular diseases in patients with suppressed HIV viremia.