The association of non-alcoholic fatty liver disease and cardiac structure and function-Framingham Heart Study

Flexible Machine Learning Estimation of Conditional Average Treatment Effects: A Blessing and a Curse

Causal inference from observational data requires untestable identification assumptions. If these assumptions apply, machine learning methods can be used to study complex forms of causal effect heterogeneity. Recently, several machine learning methods were developed to estimate the conditional average treatment effect (ATE). If the features at hand cannot explain all heterogeneity, the individual treatment effects can seriously deviate from the conditional ATE. In this work, we demonstrate how the distributions of the individual treatment effect and the conditional ATE can differ when a causal random forest is applied. We extend the causal random forest to estimate the difference in conditional variance between treated and controls. If the distribution of the individual treatment effect equals that of the conditional ATE, this estimated difference in variance should be small. If they differ, an additional causal assumption is necessary to quantify the heterogeneity not captured by the distribution of the conditional ATE. The conditional variance of the individual treatment effect can be identified when the individual effect is independent of the outcome under no treatment given the measured features. Then, in the cases where the individual treatment effect and conditional ATE distributions differ, the extended causal random forest can appropriately estimate the variance of the individual treatment effect distribution, whereas the causal random forest fails to do so.

Metabolic dysfunction-associated steatotic liver disease and the heart

The prevalence and severity of metabolic dysfunction-associated steatotic liver disease (MASLD) are increasing. Physicians who treat patients with MASLD may acknowledge the strong coincidence with cardiometabolic disease, including atherosclerotic cardiovascular disease (asCVD). This raises questions on co-occurrence, causality, and the need for screening and multidisciplinary care for MASLD in patients with asCVD, and vice versa. Here, we review the interrelations of MASLD and heart disease and formulate answers to these matters. Epidemiological studies scoring proxies for atherosclerosis and actual cardiovascular events indicate increased atherosclerosis in patients with MASLD, yet no increased risk of asCVD mortality. MASLD and asCVD share common drivers: obesity, insulin resistance and type 2 diabetes mellitus (T2DM), smoking, hypertension, and sleep apnea syndrome. In addition, Mendelian randomization studies support that MASLD may cause atherosclerosis through mixed hyperlipidemia, while such evidence is lacking for liver-derived procoagulant factors. In the more advanced fibrotic stages, MASLD may contribute to heart failure with preserved ejection fraction by reduced filling of the right ventricle, which may induce fatigue upon exertion, often mentioned by patients with MASLD. Some evidence points to an association between MASLD and cardiac arrhythmias. Regarding treatment and given the strong co-occurrence of MASLD and asCVD, pharmacotherapy in development for advanced stages of MASLD would ideally also reduce cardiovascular events, as has been demonstrated for T2DM treatments. Given the common drivers, potential causal factors and especially given the increased rate of cardiovascular events, comprehensive cardiometabolic risk management is warranted in patients with MASLD, preferably in a multidisciplinary approach.

Non-Alcoholic Fatty Liver Disease (NAFLD) and risk of new-onset heart failure: a retrospective analysis of 173,966 patients

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) represents the leading cause of chronic liver disease. Its high mortality and morbidity are mainly caused by non-hepatic comorbidities and their clinical complications. Accumulating evidence suggests an association between NAFLD and heart failure (HF), but large-scale data analyses from Germany are scarce.

METHODS

Using the Disease Analyzer database (IQVIA), this analysis retrospectively evaluated two cohorts of outpatients with and without NAFLD with respect to the cumulative incidence of HF as the primary outcome between January 2005 and December 2020. Cohorts were propensity score matched for sex, age, index year, yearly consultation frequency, and known risk factors for HF.

RESULTS

A total of 173,966 patients were included in the analysis. Within 10 years of the index date, 13.2% vs. 10.0% of patients with and without NAFLD were newly diagnosed with HF (p < 0.001). This finding was supported by univariate Cox regression analysis in which NAFLD was found to be significantly associated with subsequent HF (Hazard Ratio (HR) 1.34, 95% Confidence Interval (CI) 1.28-1.39, p < 0.001). The association between NAFLD and HF was observed across all analysed age groups and as comparable between both men (HR 1.30, 95% CI 1.23-1.38; p < 0.001) and women (HR: 1.37, 95% CI 1.29-1.45; p < 0.001).

CONCLUSION

NAFLD is significantly associated with an increased cumulative incidence of HF, which, given its rapidly increasing global prevalence, could be crucial to further reduce its high mortality and morbidity. We recommend risk stratification within a multidisciplinary approach for NAFLD patients, including systematic prevention or early detection strategies for HF.

Non-Alcoholic Fatty Liver Disease and Echocardiographic Parameters of Left Ventricular Diastolic Function: A Systematic Review and Meta-Analysis

The cardiovascular implications of non-alcoholic fatty liver disease (NAFLD) have been associated with heart failure with preserved ejection fraction (HFpEF). The purpose of this review was to conduct a bibliographic search regarding the correlation between NAFLD and the echocardiographic parameters of left ventricular diastolic function. A systematic literature search was conducted in PubMed and Embase for original research data reporting on the association of NAFLD with diastolic function markers [E/e', left atrial volume index (LAVi), left ventricular mass index (LVMi)]. Meta-analysis was performed using the meta and dmetar packages in R studio v.1.4.1106, with p < 0.05 values being considered significant. Results are expressed as the standardized mean difference (SMD) for continuous variables and as the odds ratio (OR) for categorical variables, with respective 95% confidence intervals (CI). Heterogeneity between studies was expressed with index Ι2. From the preliminary search, 2619 articles were found from which 31 studies were included in the final statistical analysis. The meta-analysis of 8 studies which reported on the prevalence of diastolic dysfunction showed that it was increased in patients with NAFLD (OR: 2.07, 95% CI 1.24-3.44 with p = 0.01, I2: 80% with p < 0.01). The meta-analysis of 21 studies showed significantly higher E/e' in NAFLD patients (SMD 1.02, 95% CI 0.43-1.61 with p < 0.001, I2: 97% with p < 0.001). Individuals with NAFLD had increased LAVi (SMD: 0.87, 95% CI 0.38-1.37 with p < 0.001, I2: 96% with p < 0.001) and LVMi (SMD: 0.89, 95% CI 0.31-1.48 with p = 0.003, I2: 100% with p < 0.001). To conclude, in the meta-analysis of 31 observational studies, NAFLD patients were found to have affected left ventricular diastolic function, supporting the hypothesis of NAFLD being associated with HFpEF.

Association Between End-Stage Liver Disease and Incident Heart Failure in an Integrated Health System

BACKGROUND

End-stage liver disease (ESLD) and heart failure (HF) often coexist and are associated with significant morbidity and mortality. However, the true incidence of HF among patients with ESLD remains understudied.

OBJECTIVE

This study aims to evaluate the association between ESLD and incident HF in a real-world clinical cohort.

DESIGN AND PARTICIPANTS

A retrospective electronic health records database analysis of individuals with ESLD and frequency-matched controls without ESLD in a large integrated health system.

MAIN MEASURES

The primary outcome was incident HF, which was defined by the International Classification of Disease codes and manually adjudicated by physician reviewers. The Kaplan-Meier method was used to estimate the cumulative incidence of HF. Multivariate proportional hazards models adjusted for shared metabolic factors (diabetes, hypertension, chronic kidney disease, coronary heart disease, body mass index) were used to compare the risk of HF in patients with and without ESLD.

KEY RESULTS

Of 5004 patients (2502 with ESLD and 2502 without ESLD), the median (Q1-Q3) age was 57.0 (55.0-65.0) years, 59% were male, and 18% had diabetes. Over a median (Q1-Q3) follow-up of 2.3 (0.6-6.0) years, 121 incident HF cases occurred. Risk for incident HF was significantly higher for patients with ESLD compared with the non-ESLD group (adjusted HR: 4.67; 95% CI: 2.82-7.75; p < 0.001), with the majority of the ESLD group (70.7%) having HF with preserved ejection fraction (ejection fraction ≥ 50%).

CONCLUSION

ESLD was significantly associated with a higher risk of incident HF, independent of shared metabolic risk factors, with the predominant phenotype being HF with preserved ejection fraction.

Loss of hepatic PPARα in mice causes hypertension and cardiovascular disease

The leading cause of death in patients with nonalcoholic fatty liver disease (NAFLD) is cardiovascular disease (CVD). However, the mechanisms are unknown. Mice deficient in hepatocyte proliferator-activated receptor-α (PPARα) (PparaHepKO) exhibit hepatic steatosis on a regular chow diet, making them prone to manifesting NAFLD. We hypothesized that the PparaHepKO mice might be predisposed to poorer cardiovascular phenotypes due to increased liver fat content. Therefore, we used PparaHepKO and littermate control mice fed a regular chow diet to avoid complications with a high-fat diet, such as insulin resistance and increased adiposity. After 30 wk on a standard diet, male PparaHepKO mice exhibited elevated hepatic fat content compared with littermates as measured by Echo MRI (11.95 ± 1.4 vs. 3.74 ± 1.4%, P < 0.05), hepatic triglycerides (1.4 ± 0.10 vs. 0.3 ± 0.01 mM, P < 0.05), and Oil Red O staining, despite body weight, fasting blood glucose, and insulin levels being the same as controls. The PparaHepKO mice also displayed elevated mean arterial blood pressure (121 ± 4 vs. 108 ± 2 mmHg, P < 0.05), impaired diastolic function, cardiac remodeling, and enhanced vascular stiffness. To determine mechanisms controlling the increase in stiffness in the aorta, we used state-of-the-art PamGene technology to measure kinase activity in this tissue. Our data suggest that the loss of hepatic PPARα induces alterations in the aortas that reduce the kinase activity of tropomyosin receptor kinases and p70S6K kinase, which might contribute to the pathogenesis of NAFLD-induced CVD. These data indicate that hepatic PPARα protects the cardiovascular system through some as-of-yet undefined mechanism.

Association of the triglyceride-glucose index with subclinical left ventricular dysfunction in type 2 diabetes mellitus patients: A retrospective cross-sectional study

AIMS/INTRODUCTION

The triglyceride-glucose (TyG) index is a simple and reliable indicator of insulin resistance, and is associated with the development and poor outcomes of cardiovascular disease. Subclinical left ventricular dysfunction (SLVD) is frequently detected in approximately one-third of diabetes patients, but it has not been established whether the TyG index correlates with SLVD. We carried out this research to evaluate the relationship between the TyG index and SLVD in type 2 diabetes mellitus patients.

MATERIALS AND METHODS

This was a cross-sectional and observational study of 183 type 2 diabetes mellitus inpatients at Nanjing Drum Tower Hospital, Nanjing, China. The TyG index and homeostasis model assessment 2 estimates for insulin resistance (HOMA2-IR) were calculated from biochemical measurements, and speckle-tracking echocardiography was carried out. According to global longitudinal strain (GLS) by echocardiography, participants were categorized into the SLVD (GLS <18%) group or the non-SLVD (GLS ≥18%) group.

RESULTS

In comparison with non-SLVD participants, SLVD participants had higher insulin resistance, as reflected by elevated TyG and HOMA2-IR indices, as well as a higher body mass index, waist circumference and triglyceride level (P < 0.05 for each). When grouped by TyG index tertiles, an elevated TyG index was correlated with other cardiometabolic risk factors, as well as a decrease in GLS. In the multivariate logistic regression analyses, the TyG index was an independent risk factor for SLVD in type 2 diabetes mellitus patients (odds ratio 2.047, 95% confidence interval 1.07-3.914, P  = 0.03), whereas HOMA2-IR was not.

CONCLUSIONS

The TyG index is independently associated with SLVD in type 2 diabetes mellitus patients and is a more reliable indicator of SLVD than HOMA2-IR.

Correlation between nonalcoholic fatty liver disease and left ventricular diastolic dysfunction in non-obese adults: a cross-sectional study

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) is associated with a greater risk of developing cardiovascular disease and have adverse impacts on the cardiac structure and function. Little is known about the effect of non-obese NAFLD upon cardiac function. We aimed to compare the echocardiographic parameters of left ventricle (LV) between non-obese NAFLD group and control group, and explore the correlation of non-obese NAFLD with LV diastolic dysfunction.

METHODS AND RESULTS

In this cross-sectional study, 316 non-obese inpatients were enrolled, including 72 participants with NAFLD (non-obese NAFLD group) and 244 participants without NAFLD (control group). LV structural and functional indices of two groups were comparatively analyzed. LV diastolic disfunction was diagnosed and graded using the ratio of the peak velocity of the early filling (E) wave to the atrial contraction (A) wave and E value. Compared with control group, the non-obese NAFLD group had the lower E/A〔(0.80 ± 0.22) vs (0.88 ± 0.35), t = 2.528, p = 0.012〕and the smaller LV end-diastolic diameter〔(4.51 ± 0.42)cm vs (4.64 ± 0.43)cm, t = 2.182, p = 0.030〕. And the non-obese NAFLD group had a higher prevalence of E/A < 1 than control group (83.3% vs 68.9%, X² = 5.802, p = 0.016) while two groups had similar proportions of LV diastolic dysfunction (58.3% vs 53.7%, X² = 0.484, p = 0.487). Multivariate logistic regression analysis showed that non-obese NAFLD was associated with an increase in E/A < 1 (OR = 6.562, 95%CI 2.014, 21.373, p = 0.002).

CONCLUSIONS

Non-obese NAFLD was associated with decrease of E/A, while more research will be necessary to evaluate risk of non-obese NAFLD for LV diastolic dysfunction in future.

From NAFLD to MAFLD: Definition, Pathophysiological Basis and Cardiovascular Implications

Non-alcoholic fatty liver disease (NAFLD) is defined as a chronic liver disease characterized by excessive fat accumulation in the liver without another obvious cause (no excessive alcohol consumption, hepatotoxic medications, toxins, viral infections, genetic hepatic diseases), therefore it is an exclusion diagnosis. The term NAFLD literally refers to non-alcohol related hepatopathy and does not adequately correlate with metabolic dysfunction and related cardiovascular risks. Therefore, researchers and scientific societies have moved towards changing the terminology. The novel nomenclature for a metabolic-associated fatty liver disease (MAFLD) has been proposed in 2020 by a group of experts to overcome the issues related to the old terminology. The diagnosis of MAFLD is based on the presence of hepatic steatosis and at least one between these three conditions: type 2 diabetes mellitus (T2DM), obesity or metabolic dysregulation. MAFLD has been shown to be an independent risk factor for cardiovascular diseases and atherosclerosis. It is better related to the main risk factors for atherosclerosis and cardiovascular diseases than NAFLD, such as dyslipidemia, T2DM and hypertension. The aim of this review is to highlight the reasons why the term NAFLD is moving to the term MAFLD, what are the conceptual basis of this choice and its clinical implications, particularly in the cardiovascular field.

Effects of treatment of non-alcoholic fatty liver disease on heart failure with preserved ejection fraction

In the past few decades, non-alcoholic fatty liver disease (NAFLD) and heart failure with preserved ejection fraction (HFpEF) have become the most common chronic liver disease and the main form of heart failure (HF), respectively. NAFLD is closely associated with HFpEF by sharing common risk factors and/or by boosting systemic inflammation, releasing other secretory factors, and having an expansion of epicardial adipose tissue (EAT). Therefore, the treatments of NAFLD may also affect the development and prognosis of HFpEF. However, no specific drugs for NAFLD have been approved by the Food and Drug Administration (FDA) and some non-specific treatments for NAFLD are applied in the clinic. Currently, the treatments of NAFLD can be divided into non-pharmacological and pharmacological treatments. Non-pharmacological treatments mainly include dietary intervention, weight loss by exercise, caloric restriction, and bariatric surgery. Pharmacological treatments mainly include administering statins, thiazolidinediones, glucagon-like peptide-1 receptor agonists, sodium-glucose cotransporter 2 inhibitors, and metformin. This review will mainly focus on analyzing how these treatments may affect the development and prognosis of HFpEF.

Cardiometabolic-based chronic disease: adiposity and dysglycemia drivers of heart failure

Heart failure (HF) is a complex clinical syndrome, associated with high rates of mortality, hospitalization, and impairment of quality of life. Obesity and type 2 diabetes are major cardiometabolic drivers, represented as distinct stages of adiposity- and dysglycemia-based chronic disease (ABCD, DBCD), respectively, and leading to cardiometabolic-based chronic disease (CMBCD). This review focuses on one aspect of the CMBCD model: how ABCD and DBCD influence genesis and progression of HF phenotypes. Specifically, the relationships of ABCD and DBCD stages with structural and functional heart disease, HF risk, and outcomes in overt HF are detailed. Also, evidence-based lifestyle, pharmacological, and procedural interventions that promote or reverse cardiac remodeling and outcomes in individuals at risk or with HF are discussed. In summary, driver-based chronic disease models for individuals at risk or with HF can expose prevention targets for more comprehensive interventions to improve clinical outcomes. Future randomized trials that investigate structured lifestyle, pharmacological, and procedural therapies specifically tailored for the CMBCD model are needed to develop personalized care plans to decrease HF susceptibility and improve outcomes.

Association between non-alcoholic fatty liver disease and risk of incident heart failure: a meta-analysis of observational studies

Background and aims:

Recent research has associated non-alcoholic fatty liver disease (NAFLD) with an increased risk of atherosclerotic cardiovascular disease. Previous studies that evaluated the association between NAFLD and risk of heart failure (HF) yielded inconsistent results, however. This meta-analysis aimed to evaluate the association between NAFLD and the risk of HF.

Methods:

We searched multiple electronic databases, including PubMed, Google Scholar, Embase and Web of Science for potential studies published from inception until 30 October 2021. Cohort studies reported multivariable-adjusted risks of incident HF in NAFLD patients comparing those without NAFLD were included.

Results:

Six cohort studies comprising 10,979,967 participants (women = 55.5%) were included in the study. The median prevalence of NAFLD in these studies was 22.2%. During a median follow-up duration of 7.0 years, 92,915 HF cases were detected. In the unadjusted model, patients with NAFLD had a greater risk of incident HF [random-effect hazard ratio (HR) = 1.47, 95% confidence interval (CI) = 1.25–1.75, I² = 99%], compared with those without NAFLD. After multivariable adjustment of confounding risk factors, NAFLD was still linked with a higher risk of HF incidence (random-effect HR = 1.36, 95% CI = 1.16–1.58, I² = 98%). The risk of HF was increased not only in patients with progressive NAFLD severity but also in those with simple steatosis. The absolute risk difference of HF in NAFLD patients compared with those without NAFLD was 11.0 (95% CI = 4.9–17.7) per 10,000 person-years after multivariable adjustment.

Conclusion:

This meta-analysis suggests that NAFLD may be associated with an increased risk of incident HF. Owing to the high heterogeneity of the published studies, however, further high-quality studies are still needed.

Non-Alcoholic Fatty Liver Disease, Liver Fibrosis, and Regional Amyloid-β and Tau Pathology in Middle-Aged Adults: The Framingham Study

BACKGROUND

Liver steatosis and fibrosis are emerging as risk factors for multiple extrahepatic health conditions; however, their relationship with Alzheimer's disease pathology is unclear.

OBJECTIVE

To examine whether non-alcoholic fatty liver disease (NAFLD) and FIB-4, a non-invasive index of advanced fibrosis, are associated with brain amyloid-β (Aβ) and tau pathology.

METHODS

The study sample included Framingham Study participants from the Offspring and Third generation cohorts who attended exams 9 (2011-2014) and 2 (2008-2011), respectively. Participants underwent 11C-Pittsburgh Compound-B amyloid and 18F-Flortaucipir tau positron emission tomography (PET) imaging and abdomen computed tomography, or had information on all components of the FIB-4 index. Linear regression models were used to assess the relationship of NAFLD and FIB-4 with regional tau and Aβ, adjusting for potential confounders and multiple comparisons.

RESULTS

Of the subsample with NAFLD information (N = 169; mean age 52±9 y; 57% males), 57 (34%) had NAFLD. Of the subsample with information on liver fibrosis (N = 177; mean age 50±10 y; 51% males), 34 (19%) had advanced fibrosis (FIB-4 >  1.3). Prevalent NAFLD was not associated with Aβ or tau PET. However, FIB-4 index was significantly associated with increased rhinal tau (β= 1.03±0.33, p = 0.002). Among individuals with prevalent NAFLD, FIB-4 was related to inferior temporal, parahippocampal gyrus, entorhinal and rhinal tau (β= 2.01±0.47, p <  0.001; β= 1.60±0.53, p = 0.007, and β= 1.59±0.47, p = 0.003 and β= 1.60±0.42, p = 0.001, respectively) and to Aβ deposition overall and in the inferior temporal and parahippocampal regions (β= 1.93±0.47, p <  0.001; β= 1.59±0.38, p <  0.001, and β= 1.52±0.54, p = 0.008, respectively).

CONCLUSION

This study suggests a possible association between liver fibrosis and early Alzheimer's disease pathology, independently of cardio-metabolic risk factors.

Pathophysiological Molecular Mechanisms of Obesity: A Link between MAFLD and NASH with Cardiovascular Diseases

Obesity is now a worldwide epidemic ensuing an increase in comorbidities’ prevalence, such as insulin resistance, type 2 diabetes (T2D), metabolic dysfunction-associated fatty liver disease (MAFLD), nonalcoholic steatohepatitis (NASH), hypertension, cardiovascular disease (CVD), autoimmune diseases, and some cancers, CVD being one of the main causes of death in the world. Several studies provide evidence for an association between MAFLD and atherosclerosis and cardio-metabolic disorders, including CVDs such as coronary heart disease and stroke. Therefore, the combination of MAFLD/NASH is associated with vascular risk and CVD progression, but the underlying mechanisms linking MAFLD/NASH and CVD are still under investigation. Several underlying mechanisms may probably be involved, including hepatic/systemic insulin resistance, atherogenic dyslipidemia, hypertension, as well as pro-atherogenic, pro-coagulant, and pro-inflammatory mediators released from the steatotic/inflamed liver. MAFLD is strongly associated with insulin resistance, which is involved in its pathogenesis and progression to NASH. Insulin resistance is a major cardiovascular risk factor in subjects without diabetes. However, T2D has been considered the most common link between MAFLD/NASH and CVD. This review summarizes the evidence linking obesity with MAFLD, NASH, and CVD, considering the pathophysiological molecular mechanisms involved in these diseases. We also discuss the association of MAFLD and NASH with the development and progression of CVD, including structural and functional cardiac alterations, and pharmacological strategies to treat MAFLD/NASH and cardiovascular prevention.

Dietary Patterns Influence Target Gene Expression through Emerging Epigenetic Mechanisms in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) refers to the pathologic buildup of extra fat in the form of triglycerides in liver cells without excessive alcohol intake. NAFLD became the most common cause of chronic liver disease that is tightly associated with key aspects of metabolic disorders, including insulin resistance, obesity, diabetes, and metabolic syndrome. It is generally accepted that multiple mechanisms and pathways are involved in the pathogenesis of NAFLD. Heredity, sedentary lifestyle, westernized high sugar saturated fat diet, metabolic derangements, and gut microbiota, all may interact on a on genetically susceptible individual to cause the disease initiation and progression. While there is an unquestionable role for gene-diet interaction in the etiopathogenesis of NAFLD, it is increasingly apparent that epigenetic processes can orchestrate many aspects of this interaction and provide additional mechanistic insight. Exciting research demonstrated that epigenetic alterations in chromatin can influence gene expression chiefly at the transcriptional level in response to unbalanced diet, and therefore predispose an individual to NAFLD. Thus, further discoveries into molecular epigenetic mechanisms underlying the link between nutrition and aberrant hepatic gene expression can yield new insights into the pathogenesis of NAFLD, and allow innovative epigenetic-based strategies for its early prevention and targeted therapies. Herein, we outline the current knowledge of the interactive role of a high-fat high-calories diet and gene expression through DNA methylation and histone modifications on the pathogenesis of NAFLD. We also provide perspectives on the advancement of the epigenomics in the field and possible shortcomings and limitations ahead.

Mitochondrial Lipid Homeostasis at the Crossroads of Liver and Heart Diseases

The prevalence of NAFLD (non-alcoholic fatty liver disease) is a rapidly increasing problem, affecting a huge population around the globe. However, CVDs (cardiovascular diseases) are the most common cause of mortality in NAFLD patients. Atherogenic dyslipidemia, characterized by plasma hypertriglyceridemia, increased small dense LDL (low-density lipoprotein) particles, and decreased HDL-C (high-density lipoprotein cholesterol) levels, is often observed in NAFLD patients. In this review, we summarize recent genetic evidence, proving the diverse nature of metabolic pathways involved in NAFLD pathogenesis. Analysis of available genetic data suggests that the altered operation of fatty-acid β-oxidation in liver mitochondria is the key process, connecting NAFLD-mediated dyslipidemia and elevated CVD risk. In addition, we discuss several NAFLD-associated genes with documented anti-atherosclerotic or cardioprotective effects, and current pharmaceutical strategies focused on both NAFLD treatment and reduction of CVD risk.

NAFLD, and cardiovascular and cardiac diseases: Factors influencing risk, prediction and treatment

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD), affecting up to around 30% of the world's adult population, causes considerable liver-related and extrahepatic morbidity and mortality. Strong evidence indicates that NAFLD (especially its more severe forms) is associated with a greater risk of all-cause mortality, and the predominant cause of mortality in this patient population is cardiovascular disease (CVD). This narrative review aims to discuss the strong association between NAFLD and increased risk of cardiovascular, cardiac and arrhythmic complications. Also discussed are the putative mechanisms linking NAFLD to CVD and other cardiac/arrhythmic complications, with a brief summary of CVD risk prediction/stratification and management of the increased CVD risk observed in patients with NAFLD.

RESULTS

NAFLD is associated with an increased risk of CVD events and other cardiac complications (left ventricular hypertrophy, valvular calcification, certain arrhythmias) independently of traditional CVD risk factors. The magnitude of risk of CVD and other cardiac/arrhythmic complications parallels the severity of NAFLD (especially liver fibrosis severity). There are most likely multiple underlying mechanisms through which NAFLD may increase risk of CVD and cardiac/arrhythmic complications. Indeed, NAFLD exacerbates hepatic and systemic insulin resistance, promotes atherogenic dyslipidaemia, induces hypertension, and triggers synthesis of proatherogenic, procoagulant and proinflammatory mediators that may contribute to the development of CVD and other cardiac/arrhythmic complications.

CONCLUSION

Careful assessment of CVD risk is mandatory in patients with NAFLD for primary prevention of CVD, together with pharmacological treatment for coexisting CVD risk factors.

Genetic and epigenetic factors determining NAFLD risk

BACKGROUND

Hepatic steatosis is a common chronic liver disease that can progress into more severe stages of NAFLD or promote the development of life-threatening secondary diseases for some of those affected. These include the liver itself (nonalcoholic steatohepatitis or NASH; fibrosis and cirrhosis, and hepatocellular carcinoma) or other organs such as the vessels and the heart (cardiovascular disease) or the islets of Langerhans (type 2 diabetes). In addition to elevated caloric intake and a sedentary lifestyle, genetic and epigenetic predisposition contribute to the development of NAFLD and the secondary diseases.

SCOPE OF REVIEW

We present data from genome-wide association studies (GWAS) and functional studies in rodents which describe polymorphisms identified in genes relevant for the disease as well as changes caused by altered DNA methylation and gene regulation via specific miRNAs. The review also provides information on the current status of the use of genetic and epigenetic factors as risk markers.

MAJOR CONCLUSION

With our overview we provide an insight into the genetic and epigenetic landscape of NAFLD and argue about the applicability of currently defined risk scores for risk stratification and conclude that further efforts are needed to make the scores more usable and meaningful.