Cardiac structure and function are altered in adults with non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease is associated with aortic valve sclerosis in patients with type 2 diabetes mellitus

Background

Recent epidemiological data suggest that non-alcoholic fatty liver disease (NAFLD) is closely associated with aortic valve sclerosis (AVS), an emerging risk factor for adverse cardiovascular outcomes, in nondiabetic and type 2 diabetic individuals. To date, nobody has investigated the association between NAFLD and AVS in people with type 2 diabetes, a group of individuals in which the prevalence of these two diseases is high.

Methods and Results

We recruited 180 consecutive type 2 diabetic patients without ischemic heart disease, valvular heart disease, hepatic diseases or excessive alcohol consumption. NAFLD was diagnosed by liver ultrasonography whereas AVS was determined by conventional echocardiography in all participants. In the whole sample, 120 (66.7%) patients had NAFLD and 53 (29.4%) had AVS. No patients had aortic stenosis. NAFLD was strongly associated with an increased risk of prevalent AVS (odds ratio [OR] 2.79, 95% CI 1.3–6.1, p<0.01). Adjustments for age, sex, duration of diabetes, diabetes treatment, body mass index, smoking, alcohol consumption, hypertension, dyslipidemia, hemoglobin A1c and estimated glomerular filtration rate did not attenuate the strong association between NAFLD and risk of prevalent AVS (adjusted-OR 3.04, 95% CI 1.3–7.3, p = 0.01).

Conclusions

Our results provide the first demonstration of a positive and independent association between NAFLD and AVS in patients with type 2 diabetes mellitus.

Left ventricular dysfunction in obese children and adolescents with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) may increase the risk for cardiac dysfunction. The present study aimed to determine whether, in children, NAFLD is associated with subclinical left ventricular (LV) structural and functional abnormalities independently of metabolic risk factors. We performed a complete echocardiographic study including tissue Doppler imaging, magnetic resonance imaging (MRI) for measurement of hepatic fat fraction (HFF) and abdominal fat mass distribution, along with lipid profile, insulin sensitivity, and high-sensitivity C-reactive protein in 108 obese children, 54 with (HFF ≥5%) and 54 without NAFLD, and 18 lean healthy subjects. The three groups were matched for age, gender, and pubertal status, and obese children with NAFLD were matched for body mass index/standard deviation score with those without NAFLD. Forty-one of the children with NAFLD underwent liver biopsy. Compared to controls and children without liver involvement, those with NAFLD had features of LV diastolic dysfunction, including higher E-to-e' ratio and lower e' tissue velocity. The Tei index (reflecting the combined systolic and diastolic LV function) was also significantly higher in NAFLD children. Among children with biopsy-proven NAFLD, 26 had definite nonalcoholic steatohepatitis (NASH) and 15 were not-NASH. Patients with definite-NASH had significantly lower e' velocity and significantly higher E-to-e' and Tei index (P < 0.001, respectively) than those without NASH. In multiple logistic regression analysis, NAFLD was the only statistically significant variable associated with increased E-to-e' ratio, whereas NAFLD and systolic blood pressure were significantly associated with increased Tei index.

CONCLUSION

Asymptomatic obese children with NAFLD exhibit features of early LV diastolic and systolic dysfunction, and these abnormalities are more severe in those with NASH.

The interactions of nonalcoholic fatty liver disease and cardiovascular diseases

A complex interaction among metabolic factors, adipose tissue lipolysis, oxidative stress, and insulin resistance results in a deleterious process that may link nonalcoholic fatty liver disease (NAFLD) with severe cardiovascular (CV) outcomes. Patients with NAFLD are at higher risk of atherosclerosis, new onset of CV events, and overall mortality. The strong association between NAFLD and CV disease should affect clinical practice, with screening and surveillance of patients with NAFLD. This review discusses the data linking these major diseases.

The Role of Non-alcoholic Fatty Liver Disease in Cardiovascular Disease

Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease in western countries and is closely related to the metabolic syndrome. When NAFLD is associated with hepatocellular damage and inflammation (non-alcoholic steatohepatitis [NASH]) it can lead to severe liver disease. However, it has become clear that NAFLD is also associated with an increased risk of cardiovascular disease (CVD), independently of classical known risk factors for the latter. In the current review we briefly summarise the current clinical evidence on the role of NAFLD in CVD and discuss the potential mechanisms by which NAFLD can be linked to the pathophysiology of CVD.

Left atrial deformation parameters in patients with non-alcoholic fatty liver disease: a 2D speckle tracking imaging study

The presence of the metabolic syndrome is a strong predictor for the presence of NASH (non-alcoholic steatohepatitis) in patients with NAFLD (non-alcoholic fatty liver disease). In the present study, we assessed LA (left atrial) deformation parameters in patients with NAFLD using 2D-STE (speckle tracking echocardiography) and to investigate if any changes exist between subgroups of the NAFLD. A total of 55 NAFLD patients and 21 healthy controls were included in the study. The diagnosis of NAFLD was based on liver biopsy. After patients were categorized into groups according to histopathological analysis (simple steatosis, borderline NASH, definitive NASH), all patients underwent echocardiography with Doppler examination. In the 2D-STE analysis of the left atrium, LA-Res (peak LA strain during ventricular systole), LA-Pump (peak LA strain during atrial systole), LA-SR(S) (peak LA strain rate during ventricular systole), LA-SR(E) (peak LA strain rate during early diastole) and LA-SR(A) (peak LA strain rate during atrial systole) were obtained. LA-Res, LA-Pump and LA-SR(A) were lower in the NAFLD group than in the control group. LA-Res was found to be significantly lower in NAFLD subgroups compared with healthy subjects (43.9±14.2 in healthy controls compared with 31.4±8.3 with simple steatosis, 32.8±12.8 with borderline NASH and 33.8±9.0 with definitive NASH). LA-Pump was significantly lower in the NAFLD group (18.2±3.1 in healthy controls compared with 13.3±4.7 with borderline NASH and 14.4±4.7 with definitive NASH). There were significant differences in LA-SR(A) between healthy controls compared with simple steatosis and borderline NASH (-1.56±0.36 compared with 1.14±0.38 and 1.24±0.32 respectively). Correlation analysis showed significant correlation of LA-Res values with E (early diastolic peak velocity)/E(m) (early diastolic mitral annular velocity) ratio (r=-0.50, P≤0.001), with LAVI (LA volume index; r=-0.45, P≤0.001) and with V(p) (propagation velocity; r=0.39, P≤0.001). 2D-STE-based LA deformation parameters are impaired in patients with NAFLD with normal systolic function. Although LA-Res and pump function parameters might be useful in estimating LV (left ventricular) filling pressure in the NAFLD patient group, it could not be used for differentiating the subgroups.

The relationship between visceral adiposity and left ventricular diastolic function: results from the Baltimore Longitudinal Study of Aging

BACKGROUND AND AIMS

It is unclear whether subcutaneous and visceral fat are differentially correlated to the decline in left ventricular (LV) diastolic function with aging. This study sought to examine the hypothesis that age-related changes in the regional fat distribution account for changes in LV diastolic function and to explore potential mediators of this association.

METHODS AND RESULTS

In this cross-sectional study, we evaluated 843 participants of the Baltimore Longitudinal Study of Aging with echocardiogram, dual-energy X-ray absorptiometry (DEXA), abdominal computed tomography (CT) and blood tests performed at the same visit. LV diastolic function was assessed by parameters of LV relaxation (E/A ratio, Em and Em/Am ratio) and LV filling pressures (E/Em ratio). Total body fat was computed by DEXA, while visceral and subcutaneous fat were determined from abdominal CT. In multivariate models adjusted for demographics, cardiovascular risk factors, antihypertensive medications, physical activity and LV mass, both visceral and subcutaneous fat were associated with LV diastolic dysfunction. When both measures of adiposity were simultaneously included in the same model, only visceral fat was significantly associated with LV diastolic dysfunction. Triglycerides and sex-hormone binding globulin, but not adiponectin and leptin, were found to be significant mediators of the relationship between visceral fat and LV diastolic function, explaining 28-47% of the association. Bootstrapping analyses confirmed the significance of these findings.

CONCLUSIONS

Increased visceral adiposity is associated with LV diastolic dysfunction, possibly through a metabolic pathway involving blood lipids and ectopic fat accumulation rather than adipokines.

Hepatic function and the cardiometabolic syndrome

Despite skeletal muscle being considered by many as the source of insulin resistance, physiology tells us that the liver is a central and cardinal regulator of glucose homeostasis. This is sometimes underestimated because, in contrast with muscle, investigations of liver function are technically very difficult. Nevertheless, recent experimental and clinical research has demonstrated clearly that, due in part to its anatomic position, the liver is exquisitely sensitive to insulin and other hormonal and neural factors, either by direct intrahepatic mechanisms or indirectly by organ cross-talk with muscle or adipose tissue. Because the liver receives absorbed nutrients, these have a direct impact on liver function, whether via a caloric excess or via the nature of food components (eg, fructose, many lipids, and trans fatty acids). An emerging observation with a possibly great future is the increase in intestinal permeability observed as a consequence of high fat intake or bacterial modifications in microbiota, whereby substances normally not crossing the gut gain access to the liver, where inflammation, oxidative stress, and lipid accumulation leads to fatty liver, a situation observed very early in the development of diabetes. The visceral adipose tissue located nearby is another main source of inflammatory substances and oxidative stress, and also acts on hepatocytes and Kupffer cells, resulting in stimulation of macrophages. Liberation of these substances, in particular triglycerides and inflammation factors, into the circulation leads to ectopic fat deposition and vascular damage. Therefore, the liver is directly involved in the development of the prediabetic cardiometabolic syndrome. Treatments are mainly metformin, and possibly statins and vitamin D. A very promising avenue is treatment of the leaky gut, which appears increasingly to be an important causal factor in hepatic insulin resistance and steatosis.

Max-IDEAL: a max-flow based approach for IDEAL water/fat separation

PURPOSE

To propose a novel approach to water/fat separation using a unique smoothness constraint.

THEORY AND METHODS

Chemical-shift based water/fat separation is an established noninvasive imaging tool for the visualization of body fat in various anatomies. Nevertheless, B0 magnetic field inhomogeneities can hamper the water/fat separation process. In this work, B0 variations are mapped using a convex-relaxed labeling model which produces a coarse estimate of the field map, while considering T2* decay during the labeling process. Fat and water components are subsequently resolved using T2*-IDEAL. An adaptive spatial filtering (ASF) was introduced to improve the robustness of the estimate. The method was tested on cardiac and abdominal datasets from healthy volunteers and nonalcoholic fatty liver disease (NAFLD) patients.

RESULTS

Out of 168 cardiac and abdominal images, only 1 case has shown water/fat swaps that can hinder the clinical interpretation of the underlying anatomy.

CONCLUSION

This work demonstrates a new water/fat separation approach that prevents the occurrence of water/fat swaps, by means of a unique smoothness constraint. Incorporating T2* effect in the labeling procedure and including the ASF processing enhance the robustness of the proposed approach and permit the procedure to handle abrupt B0 variations within the field of view.

Non-alcoholic fatty liver disease is associated with an increased prevalence of atrial fibrillation in hospitalized patients with type 2 diabetes

NAFLD (non-alcoholic fatty liver disease) and AF (atrial fibrillation) are two pathological conditions that are highly prevalent in developed countries and share multiple risk factors. The relationship between NAFLD and AF in Type 2 diabetes is currently unknown. We studied a hospital-based sample of 702 patients with Type 2 diabetes discharged from our Division of Endocrinology during 2007-2011. The diagnosis of AF was confirmed in affected participants on the basis of ECGs and medical history by experienced cardiologists. NAFLD was defined by ultrasonographic detection of hepatic steatosis in the absence of other liver diseases. Of the 702 hospitalized patients included in the study, 514 (73.2%) of them had NAFLD and 85 (12.1%) had persistent or permanent AF. NAFLD was associated with an increased risk of prevalent AF {OR (odds ratio), 3.04 [95% CI (confidence interval), 1.54-6.02]; P<0.001}. Adjustments for age, sex, systolic BP (blood pressure), HbA1c, (glycated haemoglobin), estimated GFR (glomerular filtration rate), total cholesterol, electrocardiographic LVH (left ventricular hypertrophy), COPD (chronic obstructive pulmonary disease), and prior history of HF (heart failure), VHD (valvular heart disease) or hyperthyroidism did not attenuate the association between NAFLD and AF [adjusted OR, 5.88 (95% CI, 2.72-12.7); P<0.001]. In conclusion, our results show that ultrasound-diagnosed NAFLD is strongly associated with an increased prevalence of persistent or permanent AF in patients with Type 2 diabetes, independently of several clinical risk factors for AF. The potential impact of NAFLD on AF deserves particular attention, especially with respect to the implications for screening and surveillance strategies in the growing number of patients with NAFLD.

Progression of NAFLD to diabetes mellitus, cardiovascular disease or cirrhosis

NAFLD is a spectrum of progressive liver disease that encompasses simple steatosis, NASH, fibrosis and, ultimately, cirrhosis. NAFLD is recognized as the hepatic component of the metabolic syndrome, as these conditions have insulin resistance as a common pathophysiological mechanism. Therefore, NAFLD is strongly associated with type 2 diabetes mellitus and abdominal obesity. As lifestyles have become increasingly sedentary and dietary patterns have changed, the worldwide prevalence of NAFLD has increased dramatically and is projected to be the principal aetiology for liver transplantation within the next decade. Importantly, a growing body of clinical and epidemiological evidence suggests that NAFLD is associated not only with liver-related morbidity and mortality, but also with an increased risk of developing both cardiovascular disease and type 2 diabetes mellitus. This article reviews the evidence that suggests NAFLD is a multisystem disease and the factors that might determine interindividual variation in the development and progression of its major hepatic and extrahepatic manifestations (principally type 2 diabetes mellitus and cardiovascular disease).

Non-alcoholic fatty liver disease is associated with an increased incidence of atrial fibrillation in patients with type 2 diabetes

Background

The relationship between non-alcoholic fatty liver disease (NAFLD) and atrial fibrillation (AF) in type 2 diabetes is currently unknown. We examined the relationship between NAFLD and risk of incident AF in people with type 2 diabetes.

Methods and Results

We prospectively followed for 10 years a random sample of 400 patients with type 2 diabetes, who were free from AF at baseline. A standard 12-lead electrocardiogram was undertaken annually and a diagnosis of incident AF was confirmed in affected participants by a single cardiologist. At baseline, NAFLD was defined by ultrasonographic detection of hepatic steatosis in the absence of other liver diseases. During the 10 years of follow-up, there were 42 (10.5%) incident AF cases. NAFLD was associated with an increased risk of incident AF (odds ratio [OR] 4.49, 95% CI 1.6–12.9, p<0.005). Adjustments for age, sex, hypertension and electrocardiographic features (left ventricular hypertrophy and PR interval) did not attenuate the association between NAFLD and incident AF (adjusted-OR 6.38, 95% CI 1.7–24.2, p = 0.005). Further adjustment for variables that were included in the 10-year Framingham Heart Study-derived AF risk score did not appreciably weaken this association. Other independent predictors of AF were older age, longer PR interval and left ventricular hypertrophy.

Conclusions

Our results indicate that ultrasound-diagnosed NAFLD is strongly associated with an increased incidence of AF in patients with type 2 diabetes even after adjustment for important clinical risk factors for AF.