Epicardial adipose tissue is an independent marker of cardiovascular risk in HIV-infected patients

Exercise to Prevent Accelerated Vascular Aging in People Living With HIV

Given advances in antiretroviral therapy, the mortality rate for HIV infection has dropped considerably over recent decades. However, people living with HIV (PLWH) experience longer life spans coupled with persistent immune activation despite viral suppression and potential toxicity from long-term antiretroviral therapy use. Consequently, PLWH face a cardiovascular disease (CVD) risk more than twice that of the general population, making it the leading cause of death among this group. Here, we briefly review the epidemiology of CVD in PLWH highlighting disparities at the intersections of sex and gender, age, race/ethnicity, and the contributions of social determinants of health and psychosocial stress to increased CVD risk among individuals with marginalized identities. We then overview the pathophysiology of HIV and discuss the primary factors implicated as contributors to CVD risk among PLWH on antiretroviral therapy. Subsequently, we highlight the functional evidence of premature vascular dysfunction as an early pathophysiological determinant of CVD risk among PLWH, discuss several mechanisms underlying premature vascular dysfunction in PLWH, and synthesize current research on the pathophysiological mechanisms underlying accelerated vascular aging in PLWH, focusing on immune activation, chronic inflammation, and oxidative stress. We consider understudied aspects such as HIV-related changes to the gut microbiome and psychosocial stress, which may serve as mechanisms through which exercise can abrogate accelerated vascular aging. Emphasizing the significance of exercise, we review various modalities and their impacts on vascular health, proposing a holistic approach to managing CVD risks in PLWH. The discussion extends to critical future study areas related to vascular aging, CVD, and the efficacy of exercise interventions, with a call for more inclusive research that considers the diversity of the PLWH population.

Adipose Tissue Dysfunction and Energy Balance Paradigms in People Living With HIV

Over the past 4 decades, the clinical care of people living with HIV (PLWH) evolved from treatment of acute opportunistic infections to the management of chronic, noncommunicable comorbidities. Concurrently, our understanding of adipose tissue function matured to acknowledge its important endocrine contributions to energy balance. PLWH experience changes in the mass and composition of adipose tissue depots before and after initiating antiretroviral therapy, including regional loss (lipoatrophy), gain (lipohypertrophy), or mixed lipodystrophy. These conditions may coexist with generalized obesity in PLWH and reflect disturbances of energy balance regulation caused by HIV persistence and antiretroviral therapy drugs. Adipocyte hypertrophy characterizes visceral and subcutaneous adipose tissue depot expansion, as well as ectopic lipid deposition that occurs diffusely in the liver, skeletal muscle, and heart. PLWH with excess visceral adipose tissue exhibit adipokine dysregulation coupled with increased insulin resistance, heightening their risk for cardiovascular disease above that of the HIV-negative population. However, conventional therapies are ineffective for the management of cardiometabolic risk in this patient population. Although the knowledge of complex cardiometabolic comorbidities in PLWH continues to expand, significant knowledge gaps remain. Ongoing studies aimed at understanding interorgan communication and energy balance provide insights into metabolic observations in PLWH and reveal potential therapeutic targets. Our review focuses on current knowledge and recent advances in HIV-associated adipose tissue dysfunction, highlights emerging adipokine paradigms, and describes critical mechanistic and clinical insights.

HIV-Related Atherosclerosis: State-of-the-Art-Review

The infection caused by the Human Immunodeficiency Virus (HIV) has spread rapidly across the globe, assuming the characteristics of an epidemic in some regions. Thanks to the introduction of antiretroviral therapy into routine clinical practice, there was a considerable breakthrough in the treatment of HIV, that is now HIV is potentially well-controlled even in low-income countries. To date, HIV infection has moved from the group of life-threatening conditions to the group of chronic and well controlled ones and the quality of life and life expectancy of HIV+ people, with an undetectable viral load is closer to that of an HIV- people. However, unsolved issues still persist. For example: people living with HIV are more prone to the age-related diseases, especially atherosclerosis. For this reason, a better understanding of the mechanisms of HIV-associated destabilization of vascular homeostasis seems to be an urgent duty, that may lead to the development of new protocols, bringing the possibilities of pathogenetic therapies to a new level. The purpose of the article was to evaluate the pathological aspects of HIV-induced atherosclerosis.

Diabetes in HIV: the Link to Weight Gain

PURPOSE OF REVIEW

The burden of metabolic diseases, including type 2 diabetes mellitus (T2DM), is rising among persons with HIV (PWH) on antiretroviral therapy (ART). This increase coincides with an aging population and a greater proportion who are overweight/obese. This review summarizes the changing epidemic of T2DM on contemporary ART, the role of weight gain, and therapeutic options.

RECENT FINDINGS

Recent studies confirm that PWH face an epidemic of obesity and T2DM, similar to the general population. Contemporary ART is associated with greater weight gain and may contribute to the risk of T2DM. Recent advances in medical weight loss therapy offer a way forward in the prevention and treatment of weight-associated T2DM. Weight gain is one of the biggest contributors to T2DM in PWH. Future studies on the role of adipose tissue distribution, adipose tissue function and clinical use of effective weight loss medications may change the paradigm of care for PWH.

Ectopic Fat and Cardiac Health in People with HIV: Serious as a Heart Attack

PURPOSE OF REVIEW

This study aims to summarize knowledge of alterations in adipose tissue distribution among people with HIV (PWH), with a focus on the cardiac depot and how this relates to the known higher risk of cardiovascular disease in this unique population.

RECENT FINDINGS

Similar to the general population, cardiac fat depots mirror visceral adipose tissue in PWH. However, altered fat distribution, altered fat quality, and higher prevalence of enlarged epicardial adipose tissue depots are associated with increased coronary artery disease among PWH. Adipose tissue disturbances present in PWH ultimately contribute to increased risk of cardiovascular disease beyond traditional risk factors. Future research should aim to understand how regulating adipose tissue quantity and quality can modify cardiovascular risk.

Higher epicardial fat in older adults living with HIV with viral suppression and relationship with liver steatosis, coronary calcium and cardiometabolic risks

OBJECTIVES

HIV infection is associated with ectopic fat deposition, which leads to chronic inflammation and cardiometabolic dysregulation. We assessed the epicardial adipose tissue (EAT) volume and its associated factors among people with HIV (PWH).

DESIGN

A cross-sectional study.

METHODS

We conducted a cross-sectional study among PWH aged at least 50 years and age-matched and sex-matched HIV-negative older individuals in Bangkok, Thailand. Participants underwent a noncontrast, cardiac computed tomography (CT) scan to assess coronary artery calcium (CAC) score and EAT between March 2016 and June 2017. Multivariate linear regression analyses were used to investigate HIV-related factors, cardiac and metabolic markers associated with EAT volume.

RESULTS

Median age was 55 years [interquartile range (IQR) 52-60] and 63% were men. Median duration of antiretroviral therapy (ART) was 16 years with 97% had HIV-1 RNA less than 50 copies/ml and median CD4 + cell count of 617 cells/μl. Median EAT volume was significantly higher in PWH [99 (IQR 75-122) cm 3 ] than HIV-negative individuals [93 (IQR 69-117) cm 3 ], P  = 0.022. In adjusted model, factors associated with EAT volume included male sex ( P  = 0.045), older age ( P  < 0.001), abnormal waist circumference ( P  < 0.001) and HOMA-IR ( P  = 0.01). In addition, higher CAC score was independently associated with EAT volume. Higher mean EAT volume was seen in PWH with severe liver steatosis than those without steatosis ( P  = 0.018). In adjusted PWH-only model, duration of HIV was significantly associated with higher EAT volume ( P  = 0.028).

CONCLUSION

In an aging cohort, PWH had higher EAT volume than HIV-negative controls. EAT was also independently associated with central fat accumulation, insulin resistance, liver steatosis and CAC score.

High rate of left ventricular hypertrophy on screening echocardiography among adults living with HIV in Malawi

BACKGROUND

There are limited data on structural heart disease among people living with HIV in southern Africa, where the success of antiretroviral therapy (ART) has drastically improved life expectancy and where risk factors for cardiovascular disease are prevalent.

METHODS

We performed a cross-sectional study of screening echocardiography among adults (≥18 years) with HIV in Malawi presenting for routine ART care. We used univariable and multivariable logistic regression to evaluate correlates of abnormal echocardiogram.

RESULTS

A total of 202 individuals were enrolled with a median age of 45 years (IQR 39-52); 52% were female, and 27.7% were on antihypertensive medication. The most common clinically significant abnormality was left ventricular hypertrophy (LVH) (12.9%, n=26), and other serious structural heart lesions were rare (<2% with ejection fraction less than 40%, moderate-severe valve lesions or moderate-severe pericardial effusion). Characteristics associated with abnormal echocardiogram included older age (OR 1.04, 95% CI 1.01 to 1.08), higher body mass index (OR 1.09, 95% CI 1.02 to 1.17), higher mean systolic blood pressure (OR 1.03, 95% CI 1.02 to 1.05) and higher mean diastolic blood pressure (OR 1.03, 95% CI 1.01 to 1.05). In a multivariable model including age, duration on ART, body mass index, and systolic and diastolic blood pressure, only mean body mass index (adjusted OR 1.10, 95% CI 1.02 to 1.19), systolic blood pressure (aOR 1.05, 95% CI 1.03 to 1.08) and diastolic blood pressure (aOR 0.96, 95% CI 0.92 to 1.00) remained associated with abnormal echocardiogram.

CONCLUSIONS

LVH was common in this population of adults on ART presenting for routine care and was associated with elevated blood pressure. Further research is needed to characterise the relationship between chronic hypertension, LVH and downstream consequences, such as diastolic dysfunction and heart failure in people living with HIV.

Cardiovascular computed tomography and HIV: The evolving role of imaging biomarkers in enhanced risk prediction

The treatment of human immunodeficiency virus (HIV) with antiretroviral (ARV) medications has revolutionised the care for these patients. The dramatic increase in life expectancy has brought new challenges in treating diseases of aging in this cohort. Cardiovascular disease (CVD) is now a leading cause of morbidity and mortality with risk matched HIV-positive patients having double the risk of MI compared to HIV-negative patients. This enhanced risk is secondary to the interplay the virus (and accessory proteins), ARV medications and traditional risk factors. The culmination of these factors can lead to a hybrid metabolic syndrome characterised by heightened ectopic fat. Cardiovascular computed tomography (CT) is ideal for quantifying epicardial adipose tissue volumes, hepatosteatosis and cardiovascular disease burden. The CVD risk attributed to disease burden and plaque morphology is well established in general populations but is less clear in HIV populations. The purpose of this review article is to appraise the latest data on CVD development in HIV-positive patients and how the use of cardiovascular CT may be used to enhance risk prediction in this population. This may have important implications on individualised treatment decisions and risk reduction strategies which will improve the care of these patients.

Coronary Artery Calcification and Plaque Characteristics in People Living With HIV: A Systematic Review and Meta-Analysis

Background

Studies have reported that people living with HIV have higher burden of subclinical cardiovascular disease, but the data are not adequately synthesized. We performed meta‐analyses of studies of coronary artery calcium and coronary plaque in people living with HIV.

Methods and Results

We performed systematic search in electronic databases, and data were abstracted in standardized forms. Study‐specific estimates were pooled using meta‐analysis. 43 reports representing 27 unique studies and involving 10 867 participants (6699 HIV positive, 4168 HIV negative, mean age 52 years, 86% men, 32% Black) were included. The HIV‐positive participants were younger (mean age 49 versus 57 years) and had lower Framingham Risk Score (mean score 6 versus 18) compared with the HIV‐negative participants. The pooled estimate of percentage with coronary artery calcium >0 was 45% (95% CI, 43%–47%) for HIV‐positive participants, and 52% (50%–53%) for HIV‐negative participants. This difference was no longer significant after adjusting for difference in Framingham Risk Score between the 2 groups. The odds ratio of coronary artery calcium progression for HIV‐positive versus ‐negative participants was 1.64 (95% CI, 0.91–2.37). The pooled estimate for prevalence of noncalcified plaque was 49% (95% CI, 47%–52%) versus 20% (95% CI, 17%–23%) for HIV‐positive versus HIV‐negative participants, respectively. Odds ratio for noncalcified plaque for HIV‐positive versus ‐negative participants was 1.23 (95% CI, 1.08–1.38). There was significant heterogeneity that was only partially explained by available study‐level characteristics.

Conclusions

People living with HIV have higher prevalence of noncalcified coronary plaques and similar prevalence of coronary artery calcium, compared with HIV‐negative individuals. Future studies on coronary artery calcium and plaque progression can further elucidate subclinical atherosclerosis in people living with HIV.

Cardiac adiposity as a modulator of cardiovascular disease in HIV

BACKGROUND

With the number of people living with human immunodeficiency virus (HIV) steadily increasing, cardiovascular disease has emerged as a leading cause of non-HIV related mortality. People living with HIV (PLWH) appear to be at increased risk of coronary artery disease and heart failure (HF), while the underlying mechanism appears to be multifactorial. In the general population, ectopic cardiac adiposity has been highlighted as an important modulator of accelerated coronary artery atherosclerosis, arrhythmogenesis and HF with preserved ejection fraction (HFpEF). Cardiac adiposity is also strongly linked with obesity, especially with visceral adipose tissue accumulation.

AIMS

This review aims to summarize the possible role of cardiac fat depositions, assessed by imaging modalities,as potential contributors to the increased cardiac morbidity and mortality seen in PLWH, as well as therapeutic targets in the current ART era.

MATERIALS & METHODS

Review of contemporary literature on this topic.

DISCUSSION

Despite antiretroviral therapy (ART), PLWH have evidence of persistent, HIV-related systemic inflammation and body fat alterations. Cardiac adiposity can play an additional role in the pathogenesis of cardiovascular disease in the HIV setting. Imaging modalities such as echocardiography, cardiac multidetector computed tomography and cardiac magnetic resonance have demonstrated increased adipose tissue. Studies show that high cardiac fat depots play an additive role in promoting coronary artery atherosclerosis and HFpEF in PLWH. Systemic inflammation due to HIV infection, metabolic adverse effects of ART, adipose alterations in the ageing HIV population, inflammation and immune activation are likely important mechanisms for adipose dysfunction and disproportionately occurrence of ectopic fat depots in the heart among PLWH.

CONCLUSIONS

High cardiac adiposity seems to plays an additive role in promoting coronary artery atherosclerosis and HFpEF in PLWH. The underlying mechanisms are multiple and warrant further investigation. Improved understanding of the regulating mechanisms that increase cardiovascular risk in HIV infection may give rise to more tailored therapeutic strategies targeting cardiac fat depots.

Association of epicardial fat with noncalcified coronary plaque volume and with low attenuation plaque in people with HIV

OBJECTIVES

People with HIV are exposed to a higher risk of coronary artery disease (CAD) compared with the general population. Epicardial fat may play a unique role in promoting coronary atherosclerosis. We measured epicardial fat in participants living with HIV and controls and investigated its association with coronary plaque volume and low attenuation plaque, a marker of plaque vulnerability.

DESIGN

This is a cross-sectional study, nested in the Canadian HIV and Aging Cohort Study, a large prospective cohort actively following participants with HIV and controls. Participants with low/intermediate cardiovascular risk without symptoms/history of CAD were invited to undergo cardiac computed tomography (CT).

METHODS

Volume of epicardial fat, coronary plaque and low attenuation component of the plaque were measured. Association between epicardial fat, coronary plaque volume and low attenuation component was tested using adjusted regression analysis.

RESULTS

A total of 169 participants with HIV and 81 controls underwent cardiac CT. Participants with HIV had a greater epicardial fat volume compared with controls (P = 0.019). In participants with HIV, epicardial fat volume was positively associated with duration of nonnucleoside reverse transcriptase inhibitors (NNRTI) (β=2.19, P = 0.004). After adjustment for cardiovascular risk factors, epicardial fat volume was positively associated to noncalcified plaque volume [odds ratio (OR) = 1.09, P = 0.028] and to the low-attenuation plaque component portion (β=0.38, P = 0.026).

CONCLUSION

The association of epicardial fat volume to noncalcified plaque volume and to low attenuation component plaque may suggest a potential mechanism by which epicardial fat could be a silent driver of CAD in the HIV population.

Epicardial adipose tissue and severe Coronavirus Disease 19

BACKGROUND

Both visceral adipose tissue and epicardial adipose tissue (EAT) have pro-inflammatory properties. The former is associated with Coronavirus Disease 19 (COVID-19) severity. We aimed to investigate whether an association also exists for EAT.

MATERIAL AND METHODS

We retrospectively measured EAT volume using computed tomography (CT) scans (semi-automatic software) of inpatients with COVID-19 and analyzed the correlation between EAT volume and anthropometric characteristics and comorbidities. We then analyzed the clinicobiological and radiological parameters associated with severe COVID-19 (O2 [Formula: see text] 6 l/min), intensive care unit (ICU) admission or death, and 25% or more CT lung involvement, which are three key indicators of COVID-19 severity.

RESULTS

We included 100 consecutive patients; 63% were men, mean age was 61.8 ± 16.2 years, 47% were obese, 54% had hypertension, 42% diabetes, and 17.2% a cardiovascular event history. Severe COVID-19 (n = 35, 35%) was associated with EAT volume (132 ± 62 vs 104 ± 40 cm³, p = 0.02), age, ferritinemia, and 25% or more CT lung involvement. ICU admission or death (n = 14, 14%) was associated with EAT volume (153 ± 67 vs 108 ± 45 cm³, p = 0.015), hypertension and 25% or more CT lung involvement. The association between EAT volume and severe COVID-19 remained after adjustment for sex, BMI, ferritinemia and lung involvement, but not after adjustment for age. Instead, the association between EAT volume and ICU admission or death remained after adjustment for all five of these parameters.

CONCLUSIONS

Our results suggest that measuring EAT volume on chest CT scans at hospital admission in patients diagnosed with COVID-19 might help to assess the risk of disease aggravation.

Pericardial Adipose Tissue Volume Is Independently Associated With Human Immunodeficiency Virus Status and Prior Use of Stavudine, Didanosine, or Indinavir

BACKGROUND

Increased pericardial adipose tissue is associated with higher risk of cardiovascular disease. We aimed to determine whether human immunodeficiency virus (HIV) status was independently associated with larger pericardial adipose tissue volume and to explore possible HIV-specific risk factors.

METHODS

Persons with HIV (PWH) were recruited from the Copenhagen Comorbidity in HIV Infection (COCOMO) Study and matched 1:1 on age and sex to uninfected controls. Pericardial adipose tissue volume was measured using cardiac computed tomography.

RESULTS

A total of 587 PWH and 587 controls were included. Median age was 52 years, and 88% were male. Human immunodeficiency virus status was independently associated with 17 mL (95% confidence interval [CI], 10-23; P < .001) larger pericardial adipose tissue volume. Larger pericardial adipose tissue volume was associated with low CD4+ nadir and prior use of stavudine, didanosine, and indinavir. Among PWH without thymidine analogue or didanosine exposure, time since initiating combination antiretroviral treatment (per 5-year use) was associated with l6 mL (95% CI, -6 to -25; P = .002) lower pericardial adipose tissue volume.

CONCLUSIONS

Human immunodeficiency virus status was independently associated with larger pericardial adipose tissue volume. Severe immunodeficiency, stavudine, didanosine, and indinavir were associated with larger pericardial adipose tissue volume. Persons with HIV with prior exposure to these drugs may constitute a distinct cardiovascular risk population.

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.

A Meta-Analysis of Different Types of Cardiac Adipose Tissue in HIV Patients

Background

Antiretroviral therapy transformed HIV infection into a chronic disease but accelerated cardiovascular disease (CVD). Both of epicardial adipose tissue (EAT) and pericardial fat (PCF) have close relationships with CVD. The associations between these two cardiac adipose tissue and HIV are unclear.

Methods

Eligible studies were searched in PubMed, Embase, Web of Science, and Scopus from database inception to March 24, 2020. The summarized standard mean difference (SMD) or weighted mean difference (WMD) with 95% confidence intervals (CIs) was used to assess the association between EAT/PCF and HIV. Subgroup analysis was performed based on EAT types. Trial sequential analysis was conducted to estimate whether the evidence of the results is sufficient.

Results

In total, 2561 HIV patients and 1767 non-HIV participants were included. Compared to the control group, EAT was significantly higher in the HIV overall group and subgroup with EAT thickness (SMD = 0.59, 95% CI: 0.24-0.95, P = 0.001; SMD = 1.10, 95% CI: 0.41-1.79, P = 0.002); however, the EAT volume and PCF volume were unchanged in the HIV group (SMD = 0.16, 95% CI: -0.07-0.39, P = 0.169; WMD = 10.78, 95% CI: -14.11-35.67, P = 0.396). Trial sequential analysis indicated that the available samples were sufficient in the HIV overall group and subgroup with EAT thickness, and more studies are needed for EAT volume and PCF volume.

Conclusions

EAT thickness was significantly higher in patients with HIV. The association between EAT/PCF volume and HIV needs more studies to confirm.

HIV and antiretroviral therapy-related fat alterations

Early in the HIV epidemic, lipodystrophy, characterized by subcutaneous fat loss (lipoatrophy), with or without central fat accumulation (lipohypertrophy), was recognized as a frequent condition among people living with HIV (PLWH) receiving combination antiretroviral therapy. The subsequent identification of thymidine analogue nucleoside reverse transcriptase inhibitors as the cause of lipoatrophy led to the development of newer antiretroviral agents; however, studies have demonstrated continued abnormalities in fat and/or lipid storage in PLWH treated with newer drugs (including integrase inhibitor-based regimens), with fat gain due to restoration to health in antiretroviral therapy-naive PLWH, which is compounded by the rising rates of obesity. The mechanisms of fat alterations in PLWH are complex, multifactorial and not fully understood, although they are known to result in part from the direct effects of HIV proteins and antiretroviral agents on adipocyte health, genetic factors, increased microbial translocation, changes in the adaptive immune milieu after infection, increased tissue inflammation and accelerated fibrosis. Management includes classical lifestyle alterations with a role for pharmacological therapies and surgery in some patients. Continued fat alterations in PLWH will have an important effect on lifespan, healthspan and quality of life as patients age worldwide, highlighting the need to investigate the critical uncertainties regarding pathophysiology, risk factors and management.

Left Ventricular Function, Epicardial Adipose Tissue, and Carotid Intima-Media Thickness in Children and Adolescents With Vertical HIV Infection

BACKGROUND

Life expectancy of HIV patients has increased considerably as a result of antiretroviral therapy (ART), and cardiovascular (CV) disease has emerged as an important late concern. People with HIV infection could have an impaired systolic function; however data on diastolic function and markers of CV risk, such as epicardial adipose tissue (EAT) and intima-media thickness (IMT), are lacking. Aim of this study is to evaluate left ventricular function, EAT, and IMT in children and adolescents with vertically acquired HIV infection.

METHODS

We enrolled 29 subjects on ART (13, 45% men; median age of 13.0, and interquartile range 9-18), and 29 age-matched controls. All patients and controls underwent echocardiographic evaluation, with study of the systolic and diastolic function and measurement of the EAT, and a carotid ultrasound study for IMT measurement.

RESULTS

Comparing HIV-infected patients to healthy controls, we found a statistically significant increase of EAT and IMT (mean ± SD) (EAT: 3.16 ± 1.05 vs 1.24 ± 0.61 mm; P < 0.0001. IMT: 0.77 ± 0.15 vs 0.51 ± 0.11 mm; P < 0.0001), and a significant reduction of ejection fraction, evaluated with the biplane Simpson method (mean ± SD) (58.5% ± 6.66% vs 66% ± 4.24%; P = 0.029). These results are not related with age, gender, degree of lipodystrophy, dyslipidemia, hyperinsulinism, and ART duration or the use of single antiretroviral classes.

CONCLUSIONS

Vertically infected HIV children and adolescents show an increased thickness of EAT and IMT, expression of potentially increased CV risk. They also show an impaired systolic function.

Obesity and Weight Gain in Persons with HIV

PURPOSE OF REVIEW

The proportion of overweight and obese persons with HIV (PWH) has increased since the introduction of antiretroviral therapy (ART). We aim to summarize recent literature on risks of weight gain, discuss adipose tissue changes in HIV and obesity, and synthesize current understanding of how excess adiposity and HIV contribute to metabolic complications.

RECENT FINDINGS

Recent studies have implicated contemporary ART regimens, including use of integrase strand transfer inhibitors and tenofovir alafenamide, as a contributor to weight gain, though the mechanisms are unclear. Metabolic dysregulation is linked to ectopic fat and alterations in adipose immune cell populations that accompany HIV and obesity. These factors contribute to an increasing burden of metabolic diseases in the aging HIV population. Obesity compounds an increasing burden of metabolic disease among PWH, and understanding the role of fat partitioning and HIV- and ART-related adipose tissue dysfunction may guide prevention and treatment strategies.

Epicardial Adipose Tissue: Clinical Biomarker of Cardio-Metabolic Risk

Epicardial adipose tissue (EAT) is part of the visceral adipose tissue (VAT) that surrounds the heart and it is a quantifiable, modifiable, and multifaceted tissue that has both local and systemic effects. When EAT is enlarged, EAT contributes to atherosclerotic cardiovascular disease (ASCVD) risk and plays a role in the development of metabolic syndrome (MetS). In this review, we will discuss the role of EAT in various facets of MetS, including type 2 diabetes mellitus (T2DM) and insulin resistance. We examine the association between EAT and liver steatosis. We also address the correlations of EAT with HIV therapy and with psoriasis. We discuss racial differences in baseline EAT thickness. We conclude that EAT measurement serves as a powerful potential diagnostic tool in assessing cardiovascular and metabolic risk. Measurement of EAT is made less costly, more convenient, and yet accurate and reliable by transthoracic echocardiography. Furthermore, modification of EAT thickness has therapeutic implications for ASCVD, T2DM, and MetS.

Epicardial adipose tissue volume and cardiovascular risk indices among asymptomatic women with and without HIV

BACKGROUND

Mechanisms underlying the heightened myocardial infarction risk among HIV-infected women (versus non-HIV-infected women) remain unclear. Our objectives were to assess epicardial adipose tissue (EAT) volume and its associations among asymptomatic women with and without HIV.

METHODS

A total of 55 HIV-infected and 27 non-HIV-infected women without known cardiovascular disease who underwent cardiac CT and metabolic/immune phenotyping were included. EAT volume derived from CT was compared among women with and without HIV, and within-group EAT associations were assessed. Next, immune and atherosclerotic plaque parameters were compared among groups stratified by HIV serostatus and high/low EAT (defined in reference to median EAT for each serostatus group).

RESULTS

Asymptomatic HIV-infected women and age-matched non-HIV-infected women with comparable mean body mass index (28 ±1 versus 29 ±1 kg/m²) had similar median (IQR) volumes of EAT (54 [41-79] versus 65 [41-78] cm³; P>0.05); however, different within-group associations were noted. Markers of monocyte activation/arterial inflammation differed by HIV serostatus/EAT volume subgroup (CXCL10 [P=0.02], sCD163 [P=0.004], sCD14 [P=0.03], Lp-PLA₂ [P=0.04]; P for overall ANOVA) and were highest among HIV-infected women with excess EAT (versus HIV-infected women without excess EAT, non-HIV-infected women with excess EAT and non-HIV-infected women without excess EAT). The percentage of segments with non-calcified coronary plaque also differed by HIV serostatus/EAT volume subgroup and was highest among HIV-infected women with excess EAT.

CONCLUSIONS

Asymptomatic women with and without HIV have similar volumes of EAT, but drivers of EAT may differ between groups. HIV-infected women with excess EAT have highest-level immune activation and the highest percentage of non-calcified plaque. Future studies are needed to determine whether EAT contributes pathogenetically to HIV-associated cardiovascular disease in women.

HIV and pericardial fat are associated with abnormal cardiac structure and function among Ugandans

OBJECTIVES

To examine the relationship between pericardial fat (PCF) and cardiac structure and function among HIV-infected patients in the sub-Saharan African country of Uganda. People living with HIV (PLHIV) have altered fat distribution and an elevated risk for heart failure. Whether altered quantity and radiodensity of fat surrounding the heart relates to cardiac dysfunction in this population is unknown.

METHODS

One hundred HIV-positive Ugandans on antiretroviral therapy were compared with 100 age and sex-matched HIV-negative Ugandans; all were >45 years old with >1 cardiovascular disease risk factor. Subjects underwent ECG-gated non-contrast cardiac CT and transthoracic echocardiography with speckle tracking strain imaging. Multivariable linear and logistic regression models were used to explore the association of PCF with echocardiographic outcomes.

RESULTS

Median age was 55% and 62% were female. Compared with uninfected controls, PLHIV had lower body mass index (27 vs 30, p=0.02) and less diabetes (26% vs 45%, p=0.005). Median left ventricular (LV) ejection fraction was 67%. In models adjusted for traditional risk factors, HIV was associated with 10.3 g/m² higher LV mass index (LVMI) (95% CI 3.22 to 17.4; p=0.005), 0.87% worse LV global longitudinal strain (GLS) (95% CI -1.66 to -0.07; p=0.03) and higher odds of diastolic dysfunction (OR 1.96; 95% CI 0.95 to 4.06; p=0.07). In adjusted models, PCF volume was significantly associated with increased LVMI and worse LV GLS, while PCF radiodensity was associated with worse LV GLS (all p<0.05).

CONCLUSIONS

In Uganda, HIV infection, PCF volume and density are associated with abnormal cardiac structure and function.

Effects of antidiabetic drugs on epicardial fat

Epicardial adipose tissue is defined as a deposit of adipocytes with pathophysiological properties similar to those of visceral fat, located in the space between the myocardial muscle and the pericardial sac. When compared with subcutaneous adipose tissue, visceral adipocytes show higher metabolic activity, lipolysis rates, increased insulin resistance along with more steroid hormone receptors. The epicardial adipose tissue interacts with numerous cardiovascular pathways via vasocrine and paracrine signalling comprised of pro- and anti-inflammatory cytokines excretion. Both the physiological differences between the two tissue types, as well as the fact that fat distribution and phenotype, rather than quantity, affect cardiovascular function and metabolic processes, establish epicardial fat as a biomarker for cardiovascular and metabolic syndrome. Numerous studies have underlined an association of altered epicardial fat morphology, type 2 diabetes mellitus (T2DM) and adverse cardiovascular events. In this review, we explore the prospect of using the epicardial adipose tissue as a therapeutic target in T2DM and describe the underlying mechanisms by which the antidiabetic drugs affect the pathophysiological processes induced from adipose tissue accumulation and possibly allow for more favourable cardiovascular outcomes though epicardial fat manipulation.

Epicardial Adipose Tissue Thickness and its Corelation with Metabolic Risk Parameters in People Living with HIV: A RIMS Study

CONTEXT

Epicardial fat envelopes the coronary vessel adventitia without fascial separation, thus pathologic inflammation in the fat may promote the growth of atherosclerotic plaque in coronary arteries in an 'outside-in' fashion. Epicardial fat is quantitatively increased in HIV compared to un-infected people.

AIMS

1. To assess Epicardial Adipose tissue (EAT) by Computed tomography (CT) in PLHIV receiving first line ART (antiretroviral therapy) 2. To correlate EAT with metabolic risk parameters.

MATERIAL AND METHODS

215 HIV-infected patients aged >18 years on first line ART were included in the cross sectional study. EAT thickness were measured by CT scan. Metabolic parameters were measured based on metabolic syndrome criteria.

STATISTICAL ANALYSIS USED

Data analysis was done using IBM SPSS version ver. 21. Probability value of less than 0.5 was taken as significant.

ETHICAL ISSUES

The study was carried out after obtaining approval from the Institutional Ethical Committee (IEC), Regional Institute of Medical Sciences, Imphal.

RESULTS

Half of the patients were found to have EAT thickness of 8.1-9 mm and 12.6% of cases had EAT of >9 mm. Mean epicardial thickness was 8.3 mm ± 0.7 mm for whole population. Triglyceride and high density lipoprotein (HDL) were also found to have positive correlation with EAT thickness (rp= 0.364, P = 0.04 and rp= 0.343, P = 0.05 respectively).

CONCLUSION

Epicardial adipose tissue thickness is increased in PLHIV receiving highly active anti retroviral therapy (HAART) and positively co-related with parameters of metabolic syndrome such as waist circumference, HDL cholesterol and triglyceride level.

Heart fat in HIV: marker or mediator of risk?

PURPOSE OF REVIEW

The review aims to summarize the literature describing the clinical impact of cardiac fat depots in patients with HIV infection.

RECENT FINDINGS

People living with HIV (PLHIV) have accelerated rates of cardiovascular disease, and are prone to the development of ectopic fat deposition. Specifically, PLHIV have higher volumes of epicardial and intracardiac fat quantified by noninvasive imaging. Higher volumes of epicardial fat may be related to antiretroviral therapy duration and chronic inflammation, independently of other measures of body adiposity such as BMI. They have been associated with increased coronary artery calcium, myocardial perfusion defects, death, and myocardial infarction. The association with risk may be partly mediated through direct actions of cytokines and adipokines produced by the adipose tissue. Furthermore, HIV-infected patients have increased myocardial fat deposition that is also associated with antiretroviral therapy duration, and may be responsible for myocardial systolic and diastolic dysfunction.

SUMMARY

PLHIV have increased fat deposition surrounding and inside the heart that may serve as an important imaging marker of risk but may also directly mediate coronary artery disease and cardiac dysfunction. Although robust data of targeted therapies is lacking, some pharmacotherapies may be able to reduce cardiac fat volumes. In the meantime, as the evidence grows, physicians may consider intensifying preventive strategies and monitoring in patients with abnormal heart fat on noninvasive imaging.

Metabolically Healthy or Metabolically Unhealthy Obese HIV-Infected Patients: Mostly a Matter of Age?

Background: Life expectancy of HIV-infected patients has increased with antiretroviral treatment (ART). Chronic diseases associated with aging, including metabolic and cardiovascular diseases are becoming more prevalent in this population. We aimed to evaluate the association of obesity and aging with cardiometabolic comorbidities and metabolic health status among patients with HIV infection. Methods: We evaluated 580 HIV-1 infected patients (71.7% male, mean age of 47.7 ± 11.5 years). We analyzed the association of age and obesity (defined by and by central obesity) with gender, duration of HIV infection, and ART, anthropometric parameters, cardiometabolic comorbidities, Framingham risk score (FRS), blood pressure, lipid profile, uric acid, liver biochemical tests, and glycemic profile. Furthermore, we analyzed the above-mentioned associations according to the category and central obesity into the metabolically healthy (MH) and unhealthy (MUH) categories. To evaluate the association of anthropometric parameters with cardiometabolic comorbidities, we performed unadjusted and adjusted logistic regression models. Results: The prevalence of excessive weight and cardiometabolic comorbidities increased with age. Patients with normal weight were younger and there was a higher proportion of female patients in the obesity group. The prevalence of hypertension and metabolic syndrome were higher among patients who were overweight or with obesity. The FRS was higher among patients with obesity. The proportion of MUH patients was higher among patients with excessive weight and central obesity. MUH patients had more cardiometabolic comorbidities and a higher FRS. In the normal weight group, MUH patients were older, and in the obesity group they were more likely to be male. The anthropometric parameter most associated with metabolic syndrome was waist circumference and that most associated with hypertension was waist-to-height ratio. The anthropometric parameter most associated with diabetes and FRS was waist-to-hip ratio. Conclusion: Patients with HIV present a high prevalence of obesity and related comorbidities. Ageing significantly contributes to metabolic dysfunction in this population. The proportion of MUH patients is higher among groups with excessive weight and central obesity, with those patients presenting a higher cardiovascular risk. Our results highlight the importance of evaluating and addressing obesity in patients with HIV, as well as metabolic comorbidities and cardiovascular risk.

Cardiac Steatosis in HIV-A Marker or Mediator of Disease?

Although people living with HIV (PLHIV) are approaching normal life expectancy, a limitation to achieving this goal is managing the higher prevalence of co-morbidities, including cardiovascular disease. Whilst ischaemic heart disease likely contributes to a large proportion of cardiac disease in the modern era of treatment, cardio-metabolic disease, including cardiac steatosis, akin to obesity-related heart disease, is also a possible mechanism of increased cardiac morbidity and mortality. HIV and other metabolic and inflammatory diseases affecting the heart, including obesity, share many cardio-metabolic abnormalities, with increased pericardial and myocardial fat content, in association with chronic systemic inflammatory changes and alterations in cardiac metabolism. Understanding the mechanisms of HIV-associated cardiac steatosis remains an important challenge, as managing the untreated metabolic and inflammatory precipitants may substantially improve cardiac outcomes for PLHIV.

Differential relationships of hepatic and epicardial fat to body composition in HIV

HIV-infected patients commonly experience changes in central and peripheral fat content as well as ectopic fat accumulation. However, whether hepatic and epicardial fat stores relate differentially to body composition or how these associations are modified by HIV status has not been well explored. A previously recruited sample of 124 HIV-infected patients and 58 healthy controls had undergone dual energy X-ray absorptiometry (DEXA) and computed tomography (CT) from which body composition measures, liver-spleen ratio, and epicardial fat volume were obtained. Unique to the HIV-infected group, there was a parabolic association between abdominal subcutaneous adipose tissue (SAT) area and liver-spleen ratio (P = 0.03, inflection point 324 cm²) such that hepatic fat content was greatest at the extremes of low and high SAT A quadratic model also closely described the relationship between mean leg fat and liver-spleen ratio among patients with HIV (P = 0.02, inflection point 4.7 kg), again suggesting greater liver fat content with both low and high leg fat. Notably, an analogous relationship of epicardial fat with SAT was not evident among HIV-infected individuals or healthy controls. In contrast, visceral adipose tissue (VAT) linearly related to both liver-spleen ratio in HIV and epicardial fat volume irrespective of HIV status in multivariable models. In conclusion, our analyses implicate both low and high SAT as risk factors for hepatic fat accumulation in HIV These findings add to growing evidence of SAT dysfunction in the setting of HIV infection, and highlight key physiologic differences between hepatic and epicardial fat depots.

Pathophysiology and management of cardiovascular disease in patients with HIV

Results from several studies have suggested that people with HIV have an increased risk of cardiovascular disease, especially coronary heart disease, compared with people not infected with HIV. People living with HIV have an increased prevalence of traditional cardiovascular disease risk factors, and HIV-specific mechanisms such as immune activation. Although older, more metabolically harmful antiretroviral regimens probably contributed to the risk of cardiovascular disease, new data suggest that early and continuous use of modern regimens, which might have fewer metabolic effects, minimises the risk of myocardial infarction by maintaining viral suppression and decreasing immune activation. Even with antiretroviral therapy, however, immune activation persists in people with HIV and could contribute to accelerated atherosclerosis, especially of coronary lesions that are susceptible to rupture. Therefore, treatments that safely reduce inflammation in people with HIV could provide additional cardiovascular protection alongside treatment of both traditional and non-traditional risk factors.

Increased pericardial fat accumulation is associated with increased intramyocardial lipid content and duration of highly active antiretroviral therapy exposure in patients infected with human immunodeficiency virus: a 3T cardiovascular magnetic resonance feasibility study

BACKGROUND

The aim of the current study was to examine whether the use of highly active antiretroviral therapy (HAART) in patients with HIV is associated with changes in pericardial fat and myocardial lipid content measured by cardiovascular magnetic resonance (CMR).

METHODS

In this prospective case-control study, we compared 27 HIV seropositive (+) male subjects receiving HAART to 22 control male subjects without HIV matched for age, ethnicity and body mass index. All participants underwent CMR imaging for determination of pericardial fat [as volume at the level of the origin of the left main coronary artery (LM) and at the right ventricular free wall] and magnetic resonance spectroscopy (MRS) for evaluation of intramyocardial lipid content (% of fat to water in a single voxel at the interventricular septum). All measurements were made by two experienced readers blinded to the clinical history of the study participants. Two-sample t-test, Spearman's correlation coefficient or Pearson's correlation coefficient and multivariable logistic regression were used for statistical analysis.

RESULTS

Pericardial fat volume at the level of LM origin was higher in HIV (+) subjects (33.4 cm(3) vs. 27.4 cm(3), p = 0.03). On multivariable analysis adjusted for age, Framingham risk score (FRS) and waist/hip ratio, pericardial fat remained significantly associated to HIV-status (OR 1.09, p = 0.047). For both HIV (+) and HIV (-) subjects, pericardial fat volume showed strong correlation with intramyocardial lipid content (r = 0.58, p < 0.0001) and FRS (r = 0.53, p = 0.0002). Among HIV (+) subjects, pericardial fat was significantly higher in patients with lipo-accumulation (37 cm(3) vs. 27.1 cm(3), p = 0.03) and showed significant correlation with duration of both HIV infection (r = 0.5, p = 0.01) and HAART (r = 0.46, p = 0.02).

CONCLUSIONS

Pericardial fat content is increased in HIV (+) subjects on chronic HAART (>5 years), who demonstrate HAART-related lipo-accumulation and prolonged HIV duration of infection. Further investigation is warranted to determine whether increased pericardial fat is associated with higher cardiovascular risk leading to premature cardiovascular events in this patient population.

Predictors of Treatment Response to Tesamorelin, a Growth Hormone-Releasing Factor Analog, in HIV-Infected Patients with Excess Abdominal Fat

BACKGROUND

Tesamorelin, a synthetic analog of human growth hormone-releasing factor, decreases visceral adipose tissue (VAT) in human immunodeficiency virus (HIV)-infected patients with lipodystrophy.

OBJECTIVES

1) To evaluate the utility of patient characteristics and validated disease-risk scores, namely indicator variables for the metabolic syndrome defined by the International Diabetes Federation (MetS-IDF) or the National Cholesterol Education Program (MetS-NCEP) and the Framingham Risk Score (FRS), as predictors of VAT reduction during tesamorelin therapy at 3 and 6 months, and 2) To explore the characteristics of patients who reached a threshold of VAT <140 cm2, a level associated with lower risk of adverse health outcomes, after 6 months of treatment with tesamorelin.

METHODS

Data were analyzed from two Phase 3 studies in which HIV-infected patients with excess abdominal fat were randomized in a 2:1 ratio to receive tesamorelin 2 mg (n = 543) or placebo (n = 263) subcutaneously daily for 6 months, using ANOVA and ANCOVA models.

RESULTS

Metabolic syndrome (MetS-IDF or MetS-NCEP) and FRS were significantly associated with VAT at baseline. Presence of metabolic syndrome ([MetS-NCEP), triglyceride levels >1.7 mmol/L, and white race had a significant impact on likelihood of response to tesamorelin after 6 months of therapy (interaction p-values 0.054, 0.063, and 0.025, respectively). No predictive factors were identified at 3 months. The odds of a VAT reduction to <140 cm2 for subjects treated with tesamorelin was 3.9 times greater than that of subjects randomized to placebo after controlling for study, gender, baseline body mass index (BMI) and baseline VAT (95% confidence interval [CI] 2.03; 7.44).

CONCLUSIONS

Individuals with baseline MetS-NCEP, elevated triglyceride levels, or white race were most likely to experience reductions in VAT after 6 months of tesamorelin treatment. The odds of response of VAT <140 cm2 was 3.9 times greater for tesamorelin-treated patients than that of patients receiving placebo.

The effect of physical activity on cardiometabolic health and inflammation in treated HIV infection

BACKGROUND

In HIV-uninfected populations, physical activity decreases mortality and inflammation. Inflammation is a potential cause of comorbidities in HIV+ adults, the evidence examining the effect of physical activity on cardiometabolic health is limited. This analysis examines the relationship between physical activity, cardiometabolic health and inflammation.

METHODS

We conducted a nested study within the SATURN-HIV trial in which 147 HIV+ adults were randomized to 10 mg daily rosuvastatin or placebo. Measures of physical activity, cardiometabolic health, inflammation and vascular disease (carotid artery intima media thickness and computed tomography-acquired measures pericardial fat volume) were assessed at baseline and through 96 weeks. Spearman correlations and multivariable analyses were used to explore relationships between physical activity, cardiometabolic health and inflammation.

RESULTS

Median age (Q1, Q3) was 46 (40.4, 52.7) years, 80% were male, 69% were African American and 46% were on protease inhibitors. Baseline median physical activity was 44 min per week (0, 150), 24% of participants performed greater than 150 min per week. At baseline, physical activity correlated with several markers of cardiometabolic health and inflammation (all P≤0.05). Over all time points median physical activity was independently associated with carotid distensibility (β=2.53; P=0.008), pericardial fat volume (β=-6.13; P=0.001) and interleukin-6 (β=-0.468; P<0.001).

CONCLUSIONS

Physical activity is associated with vascular disease, endothelial function, and may be an adjuvant to decreasing comorbidities in HIV+ adults. Further studies should examine long-term effects of physical activity on cardiometabolic health and inflammation in this population. Clinicaltrials.gov NCT01218802.

Epicardial adipose tissue and coronary artery calcium predict incident myocardial infarction and death in HIV-infected patients

BACKGROUND

Epicardial adipose tissue (EAT) and coronary artery calcium (CAC) have been associated with incident coronary artery disease (CAD) and all-cause mortality in the general population. Their prognostic impact in HIV is unknown.

METHODS

Observational study of 843 consecutive HIV-infected patients receiving antiretroviral therapy for at least 6 months. Risk stratification was performed with coronary artery calcium (CAC) scoring and EAT screening. Patients were followed for CAD and all-cause mortality for a median of 2.8 years accounting for a total of 2572 patient-year follow-up.

RESULTS

Mean patient age was 50 ± 8 years and 69% were men. At baseline EAT was associated with male gender, age, waist circumference, visceral adipose tissue, and lipodystrophy, while CAC score ≥ 100 was associated with male gender, age and total cholesterol. During follow-up 33 patients suffered an event (15 incident myocardial infarctions and 18 deaths); the EAT volume was larger and the CAC score was higher in patients with events (p = 0.038 and p = 0.001 respectively). Multivariable regression analyses demonstrated that the upper tertile of EAT (≥ 93 cc; OR 2.15, 95% CI 1.06 - 4.39, p = 0.034), and CAC score ≥ 100 (OR 3.37, 95% CI 1.49 - 7.60, p = 0.003) were independent predictors of events after adjusting for age and sex.

CONCLUSIONS

In this observational cohort of HIV patients, EAT and CAC were independent predictors of hard outcomes after a median follow-up of approximately 3 years.

Cardiovascular disease in HIV patients: from bench to bedside and backwards

HIV patients are exposed to a higher risk of adverse cardiovascular events, due to complex interactions between traditional risk factors and HIV infection itself in terms of ongoing endothelial dysfunctional immune activation/inflammation and increased risk of thrombosis. On the other hand, long-span antiretroviral therapy administration still raises questions on its long-term safety in an era in which life expectancy is becoming longer and longer while treatment of non-HIV-related serious events is increasingly raising concern. In this article, we will critically analyse the current knowledge of pathological and clinical aspects pertaining to the increased risk of cardiovascular events associated with HIV.

Epicardial fat is associated with duration of antiretroviral therapy and coronary atherosclerosis

OBJECTIVE

Cytokines released by epicardial fat are implicated in the pathogenesis of atherosclerosis. HIV infection and antiretroviral therapy have been associated with changes in body fat distribution and coronary artery disease. We sought to determine whether HIV infection is associated with greater epicardial fat and whether epicardial fat is associated with subclinical coronary atherosclerosis.

DESIGN

We studied 579 HIV-infected and 353 HIV-uninfected men aged 40-70 years with noncontrast computed tomography to measure epicardial adipose tissue (EAT) volume and coronary artery calcium (CAC). Total plaque score (TPS) and plaque subtypes (noncalcified, calcified, and mixed) were measured by coronary computed tomography angiography in 706 men.

METHODS

We evaluated the association between EAT and HIV serostatus, and the association of EAT with subclinical atherosclerosis, adjusting for age, race, and serostatus and with additional cardiovascular risk factors and tested for modifying effects of HIV serostatus.

RESULTS

HIV-infected men had greater EAT than HIV-uninfected men (P=0.001). EAT was positively associated with duration of antiretroviral therapy (P=0.02), specifically azidothymidine (P<0.05). EAT was associated with presence of any coronary artery plaque (P=0.006) and noncalcified plaque (P=0.001), adjusting for age, race, serostatus, and cardiovascular risk factors. Among men with CAC, EAT was associated with CAC extent (P=0.006). HIV serostatus did not modify associations between EAT and either CAC extent or presence of plaque.

CONCLUSION

Greater epicardial fat volume in HIV-infected men and its association with coronary plaque and antiretroviral therapy duration suggest potential mechanisms that might lead to increased risk for cardiovascular disease in HIV.

Epicardial fat: definition, measurements and systematic review of main outcomes

Epicardial fat (EF) is a visceral fat deposit, located between the heart and the pericardium, which shares many of the pathophysiological properties of other visceral fat deposits, It also potentially causes local inflammation and likely has direct effects on coronary atherosclerosis. Echocardiography, computed tomography and magnetic resonance imaging have been used to evaluate EF, but variations between methodologies limit the comparability between these modalities.

We performed a systematic review of the literature finding associations of EF with metabolic syndrome and coronary artery disease. The summarization of these associations is limited by the heterogeneity of the methods used and the populations studied, where most of the subjects were at high cardiovascular disease risk.

EF is also associated with other known factors, such as obesity, diabetes mellitus, age and hypertension, which makes the interpretation of its role as an independent risk marker intricate. Based on these data, we conclude that EF is a visceral fat deposit with potential implications in coronary artery disease. We describe the reference values of EF for the different imaging modalities, even though these have not yet been validated for clinical use. It is still necessary to better define normal reference values and the risk associated with EF to further evaluate its role in cardiovascular and metabolic risk assessment in relation to other criteria currently used.

Visceral adipose tissue as a source of inflammation and promoter of atherosclerosis

The current epidemic of obesity with the associated increasing incidence of insulin resistance, diabetes mellitus and atherosclerosis affecting a large proportion of the North American and Western populations, has generated a strong interest in the potential role of visceral adipose tissue in the development of atherosclerosis and its complications. The intra-abdominal and epicardial space are two compartments that contain visceral adipose tissue with a similar embryological origin. These visceral fats are highly inflamed in obese patients, patients with the metabolic syndrome and in those with established coronary artery disease; additionally they are capable of secreting large quantities of pro-inflammatory cytokines and free fatty acids. There is accumulating evidence to support a direct involvement of these regional adipose tissue deposits in the development of atherosclerosis and its complicating events, as will be reviewed in this article.

Initiation of antiretroviral therapy at high CD4 cell counts: does it reduce the risk of cardiovascular disease?

PURPOSE OF REVIEW

Inflammation and immune activation associated with untreated HIV infection may increase the risk for cardiovascular disease (CVD) and are not entirely reversed by antiretroviral therapy (ART). Although older ART regimens were associated with drug-specific risks for CVD, this may not be true for modern ART. Thus, with regard to CVD risk, the net benefit of initiating ART at higher CD4 T-cell counts remains unclear.

RECENT FINDINGS

In addition to the well established risk of coronary heart disease, emerging evidence now suggests that chronic HIV infection is associated with higher risk of ischemic stroke, heart failure, and arrhythmias. These epidemiologic studies have associated immunodeficiency and active viral replication with higher CVD risk. Novel methods of imaging subclinical vascular disease continue to implicate inflammation and immune activation as likely mediators of CVD among patients with HIV. Newer generation protease inhibitors, chemokine receptor 5 antagonists, and integrase inhibitors do not appear to be associated with the adverse cardiometabolic risks of older drugs.

SUMMARY

Recent evidence suggests that treating HIV infection with ART may reduce the risk of CVD, even at higher CD4 T-cell counts; however, the definitive answer to this question will come from clinical trials and long-term observational studies.

Hybrid myocardial imaging for risk stratification prior to kidney transplantation: added value of coronary calcium and epicardial adipose tissue

BACKGROUND

Patient selection and optimal approach to risk stratification prior to kidney transplantation remain uncertain. We sought new predictors of an abnormal myocardial perfusion (MYP) stress test result.

METHODS

Retrospective study of 411 consecutive chronic kidney disease stages 4-5D patients awaiting kidney transplantation referred for risk stratification. PET-CT or SPECT-CT was used to assess MYP and quantify coronary artery calcium (CAC) and epicardial adipose tissue (EAT). Abnormal MYP was defined as a perfusion defect involving ≥5% of the left ventricular myocardium.

RESULTS

Fixed or reversible MYP defects were present in 41 patients (10%). Male sex, smoking, and history of cardiovascular disease were more prevalent; age was higher and CAC and EAT were greater in patients with MYP defects than in those with normal MYP. On multivariate logistic regression, EAT and CAC were independent predictors of abnormal MYP while diabetes mellitus showed a borderline association (P = .08). EAT added incremental diagnostic value to a model including age, CAC and diabetes mellitus [AUC 0.73 (95% CI 0.64-0.81) to 0.76 (95% CI 0.68-0.84; P = .02)]. Furthermore, the model containing EAT showed improved diagnostic discrimination.

CONCLUSIONS

Abnormal MYP on screening stress testing appears to be rare in patients awaiting kidney transplantation suggesting an excess of testing. EAT and CAC may help predict what patients are at higher risk of developing abnormalities of MYP under stress.

Silent ischemic heart disease and pericardial fat volume in HIV-infected patients: a case-control myocardial perfusion scintigraphy study

OBJECTIVES

to determine the prevalence of asymptomatic ischemic heart disease (IHD) in HIV patients by myocardial perfusion scintigraphy (MPS) and to determine the value of coronary artery calcium score (CACS), carotid intima-media thickness (cIMT) and pericardial fat volume as screening tools for detection of IHD in subjects with HIV.

BACKGROUND

Patients with HIV seem prone to early development of IHD.

METHODS

105 consecutive HIV patients (mean age 47.4 years; mean duration of HIV 12.3 years; mean CD4+ cell count 636×10⁶/L; all receiving antiretroviral therapy) and 105 controls matched for age, gender and smoking status, without history of IHD were recruited. MPS, CACS, cIMT, pericardial fat volume, and cardiovascular risk scores were measured.

RESULTS

HIV patients demonstrated higher prevalence of perfusion defects than controls (18% vs. 0%; p<0.001) despite similar risk scores. Of HIV patients with perfusion defects, 42% had a CACS = 0. CACS and cIMT were similar in HIV patients and controls. HIV patients on average had 35% increased pericardial fat volume and increased concentration of biomarkers of atherosclerosis in the blood. HIV patients with myocardial perfusion defects had increased pericardial fat volume compared with HIV patients without perfusion defects (314±43 vs. 189±12 mL; p<0.001).

CONCLUSIONS

HIV patients had an increased prevalence of silent IHD compared to controls as demonstrated by MPS. The finding was strongly associated with pericardial fat volume, whereas cardiovascular risk scores, cIMT and CACS seem less useful as screening tools for detection of myocardial perfusion defects in HIV patients.

Perivascular fat, inflammation, and cardiovascular risk in HIV-infected patients on antiretroviral therapy

BACKGROUND

HIV-infection is characterized by chronic immune activation that persists despite effective antiretroviral therapy (ART) and is associated with elevated cardiovascular risk. Whether specific perivascular fat depots are associated with inflammation in HIV is unknown.

METHODS

In a cross-sectional study, epicardial (EAT) and thoracic periaortic (TAT) adipose tissue volumes were measured by computed tomography in 100 HIV-infected adults, on stable ART, with LDL-cholesterol ≤130 mg/dL and evidence of heightened T-cell activation (CD8+CD38+HLA-DR+ ≥19%) or increased inflammation (high sensitivity C-reactive protein ≥2 mg/L).

RESULTS

Overall, 77% were males and 70% African American. Mean (standard deviation) age and body mass index were 47 (10) years and 28 (6.4) kg/m(2), respectively. All subjects had HIV-1 RNA <1000 copies/mL with mean (standard deviation) CD4+ T cell count of 665 (280) cells/μL; 50% were on a protease inhibitor. EAT and TAT were correlated with each other (r = 0.766, p < 0.0001). Both were associated with metabolic syndrome, atherogenic lipid profile, insulin resistance, total and central body fat, serum biomarkers of inflammation, and soluble CD163, but not with cellular immune activation markers. In multivariable models that adjusted for age, sex, and other measures of adiposity, both perivascular fat depots were independently associated with the presence of coronary calcium.

CONCLUSIONS

Perivascular fat is associated with soluble CD163, biomarkers of inflammation, insulin resistance, and subclinical atherosclerosis in this population of virologically suppressed HIV-infected patients on ART. The association of perivascular fat with coronary artery calcification appears to be independent of other measures of adiposity.

Impact of epicardial fat volume on coronary artery disease in symptomatic patients with a zero calcium score

BACKGROUND

This study sought to evaluate the prevalence of coronary artery disease (CAD) and the impact of epicardial fat volume (EFV) on CAD in symptomatic patients with a zero calcium score (CS) using multislice computed tomography (MSCT).

METHODS

In this study, 1308 consecutive symptomatic patients who underwent 64-slice MSCT with a zero CS were evaluated. EFV was quantified with CS data sets. Presence of an obstructive plaque (diameter stenosis >50%) and a CT-derived vulnerable plaque, which was defined as a plaque with remodeling index >1.10 and mean CT density value <3 0HU, was assessed with a CT coronary angiography.

RESULTS

Obstructive plaques were detected in 86 patients (7%) and CT-derived vulnerable plaques in 63 (5%). EFV was larger in patients with obstructive plaques than no plaque (124.3 ± 43.2 cm(3) vs. 95.1 ± 40.3 cm(3); p<0.01). Patients with CT-derived vulnerable plaques had a greater amount of EFV than no plaque (133.0 ± 40.2 cm(3) vs. 95.1 ± 40.3 cm(3); p<0.01). Multivariate analysis revealed EFV as a predictor of the presence of an obstructive and a CT-derived vulnerable plaque (per 10 cm(3); Odds ratio (OR) 1.10; 95% confidence interval (CI), 1.04-1.16; p<0.01 and OR 1.19; 95% CI, 1.12-1.27; p<0.01). The combination of EFV and Framingham risk score (FRS) resulted in an area under the receiver-operating characteristic curve for prediction of obstructive and CT-derived vulnerable plaque of 0.75 and 0.75, which was significantly higher than 0.68 and 0.64 for FRS alone (p=0.02 and p<0.01).

CONCLUSIONS

A zero CS doesn't exclude CAD and EFV can be a useful marker of CAD in symptomatic zero CS patients.

The association of epicardial adipose tissue with coronary artery calcification among HIV-infected men

Little data exist regarding the association of epicardial adipose tissue (EAT) and cardiovascular disease among HIV-infected persons. Among 213 HIV-infected men, there was a significant association between protease inhibitor use and increasing EAT volume. EAT was significantly associated with coronary artery calcium greater than 100. The elevated coronary artery disease risk in HIV-infected men may be partially explained by EAT associated with protease inhibitor use.

Parallel increase of subclinical atherosclerosis and epicardial adipose tissue in patients with HIV

BACKGROUND

Epicardial adipose tissue (EAT) may contribute to the development of coronary atherosclerosis via paracrine secretion of inflammatory cytokines.

METHODS

This is a prospective, observational study of 240 consecutive HIV-infected patients receiving antiretroviral therapy. All patients underwent 2 sequential chest computed tomographic scans to assess the change in coronary artery calcium (CAC), a marker of subclinical atherosclerosis, and EAT volume. Patients with known cardiovascular disease were excluded. Factors independently associated with EAT change were explored using multivariable linear regression analyses. The association between EAT increase and CAC progression was explored using logistic regression analyses.

RESULTS

Two hundred forty patients were included. Patients' mean age was 47.5 ± 8 years, and 68% were men. The median interval between computed tomographic scans was 18.7 months (interquartile range 10-27 months). Men showed a larger increase in EAT (5 ± 14.2 cm(3)) than did women (-0.45 ± 8.8 cm(3), P = .007). Factors independently associated with change in EAT were CD4(+) recovery (β = 0.43, CI 0.05-0.82) and male gender (β = 5.65, CI, 1.05-10.26). Change in EAT was independently associated with CAC progression (odds ratio 1.04, 95% CI 1.004-1.88, P = .030) after adjusting for traditional cardiovascular risk factors.

CONCLUSIONS

In this cohort of patients with HIV receiving antiretroviral therapy, male gender and CD4(+) were independent predictors of EAT increase, and there was a parallel progression of CAC and EAT. Abnormal immunoreactivity associated with T-lymphocyte recovery should be further studied as a determinant of atherosclerosis progression in HIV-infected patients.

Review article: fructose in non-alcoholic fatty liver disease

BACKGROUND

The role of excess fructose intake in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) has recently received increasing attention, but the pathophysiology of this relationship has been only partly elucidated.

AIM

To provide an overview of the potential role played by fructose in the pathogenesis of NAFLD by focusing on both indirect and direct harmful effects.

METHODS

Experimental and clinical studies which investigated the relation of fructose with NAFLD are reviewed.

RESULTS

Several factors may potentially contribute to fructose-induced NAFLD, including the induction of the metabolic syndrome, copper deficiency, bacterial translocation from the gut to the liver, the formation of advanced glycation endproducts and a direct dysmetabolic effect on liver enzymes.

CONCLUSIONS

Experimentally-increased fructose intake recapitulates many of the pathophysiological characteristics of the metabolic syndrome in humans, which may in turn lead to NAFLD. However, the majority of experimental studies tend to involve feeding excessively high levels of fructose (60-70% of total energy intake) which is not reflective of average human intake. Hopefully, the combination of in vivo, in vitro and genetic research will provide substantial mechanistic evidence into the role of fructose in NAFLD development and its complications.

Ectopic fat is linked to prior cardiovascular events in men with HIV

Epicardial Adipose Tissue (EAT) has been associated with adverse cardiovascular events in the general population. We studied the association of general adiposity measures (body mass index, waist circumference) and ectopic adipose tissue [visceral adipose tissue (VAT); liver fat (LF); EAT) with prevalent cardiovascular disease (CVD) (prior myocardial infarction, coronary revascularization, stroke, peripheral vascular disease] in 583 HIV-infected men. VAT, EAT, and LF (liver/spleen attenuation ratio < 1.1) were measured by computed tomography. Patients' mean age was 48.5 ± 8.1 years, prior CVD was present in 33 (5.7%) patients. Factors independently associated with CVD on multivariable analyses were age [incidence-rate ratio (IRR) = 1.07, 95% confidence interval (CI): 1.02 to 1.12], smoking (IRR = 2.70, 95% CI: 1.22 to 6.01), Center for Disease Control group C (IRR = 3.09, 95% CI: 1.41 to 6.76), EAT (IRR = 1.13, 95% CI: 1.04 to 1.24, per 10 cm), LF (IRR = 1.17, 95% CI: 1.04 to 1.32), and VAT (IRR = 1.05, 95% CI: 1.00 to 1.10, per 10 cm). Ectopic fat but not general adiposity measures were associated with prevalent CVD in men with HIV.

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.