Metabolic syndrome and insulin resistance are associated with abnormal left ventricular diastolic function and structure independent of blood pressure and fasting plasma glucose level. Int J Cardiol. 2012;159:107-111. [PMID: 21392830 DOI: 10.1016/j.ijcard.2011.02.039]

Metabolic syndrome, left ventricular diastolic dysfunction and heart failure with preserved ejective fraction

Metabolic syndrome (MetS) encompasses a cluster of interrelated conditions, including obesity, hyperglycemia, hyperlipidemia, and hypertension, and has been established as a significant risk factor for cardiovascular events and heightened mortality. At its core, insulin resistance serves as the primary underlying mechanism driving the development of MetS. The prevalence of MetS is rising at an alarming rate, posing a significant public health challenge worldwide. Even in the absence of overt obstructive coronary artery disease or valvular heart disease, patients with MetS often exhibit adverse cardiac remodeling and myocardial dysfunction. Left ventricular hypertrophy (LVH) and left ventricular diastolic dysfunction (LVDD) are the leading manifestations of heart failure with preserved ejection fraction (HFpEF). Abnormal myocardial substrate utilization, neurohormonal activation, interstitial fibrosis, coronary microvascular dysfunction, and metabolic inflammation have all been implicated in the development and progression of adverse cardiac remodeling associated with MetS. However, despite the tremendous research produced on this subject, HFpEF remains highly prevalent in such a population. The early diagnosis of abnormal cardiac remodeling would enable optimal effective therapies to prevent the progression of the disease to the symptomatic phase. HFpEF encompasses a diverse range of pathological processes. In these patients, LVDD and elevated left ventricular filling pressure are the primary manifestations. Echocardiography remains the popular imaging modality for the assessment of LVDD and LV filling pressure. The article aims to review recent articles covering the association between MetS components or MetS and LVDD in HFpEF.

The Relationship Between Insulin Resistance Indicated by Triglyceride and Glucose Index and Left Ventricular Hypertrophy and Decreased Left Ventricular Diastolic Function with Preserved Ejection Fraction

Aim

The evidence on the association between insulin resistance (IR) and the prevalence or incidence of cardiac dysfunction has been controversial, and the relationship between pre-diabetic IR and cardiac function is lacking. Large sample studies in the Chinese general population are urgently needed to explore the association between IR and the risk of left ventricular hypertrophy (LVH) and decreased left ventricular diastolic function with preserved ejection fraction (LVDFpEF).

Methods

Based on a National Health Check-up database in China, we conducted a multicenter cross-sectional retrospective study in 344,420 individuals. Furthermore, at a single center, we performed two retrospective longitudinal studies encompassing 8270 and 5827 individuals to investigate the association between IR and the development of new-onset LVH and LVDFpEF, respectively. The median follow-up duration exceeded 2.5 years. The triglyceride and glucose (TyG) index, known for its high sensitivity in detecting IR, serves as a reliable alternative marker of IR. The logistic and cox proportional hazard regression models were used to determine the relationships.

Results

In the cross-sectional study, IR showed a positive association with the prevalence of LVH and decreased LVDFpEF after adjusting for confounders. In the longitudinal cohort, IR was also correlated with the new onset of LVH and decreased LVDFpEF, with hazard ratios (HR) of 1.986 (95% CI: 1.307, 3.017) and 1.386 (95% CI: 1.167, 1.647) in the fourth quartile of TyG levels compared to the lowest quartile, respectively, after adjusting for confounders. The subgroup analysis in non-hypertensive or non-diabetic people and the sensitivity analysis in the population with homeostasis model assessment of insulin resistance (HOMA-IR) further verified the above-mentioned results.

Conclusion

IR was associated with LVH and decreased LVDFpEF. Effective management of IR may prevent or delay the development of adverse LVH and decreased LVDFpEF.

Association between glycosylated hemoglobin levels, diabetes duration, and left ventricular diastolic dysfunction in patients with type 2 diabetes and preserved ejection fraction: a cross-sectional study

Background

We aimed to explore the intricate interplay between glycated hemoglobin (HbA1C) levels, disease duration, and left ventricular diastolic dysfunction in patients with type 2 diabetes mellitus (T2DM) characterized by preserved ejection fraction.

Methods

A cross-sectional study was conducted at the Second Affiliated Hospital of Hebei Medical University from January 2022 to December 2022. A total of 114 inpatients from the Department of Endocrinology were randomly selected based on the inclusion and exclusion criteria. Patients with T2DM were stratified into three subgroups, each comprising 38 patients, based on disease duration and HbA1C levels. A sub-analysis was conducted to explore variations among these three distinct groups. A control group comprised 38 age, gender, body mass index (BMI), and smoking habit-matched healthy volunteers form the Physical Examination Center of the same hospital. General demographic information, biochemical results, and echocardiographic data were collected, and correlation and linear regression analyses were performed.

Results

Diabetic patients exhibited lower E/A values (0.85 (0.72, 1.17) vs. 1.20 (0.97, 1.30)) and elevated E/e' values (9.50 (8.75, 11.00) vs. 9.00 (7.67, 9.85)) compared to their normal controls. In the subgroup analysis, patients with a disease duration exceeding 2 years displayed reduced E/A values (0.85 (0.75, 1.10) vs. 1.10 (0.80, 1.30)) and elevated E/e' values (9.80 (9.20, 10.80) vs. 8.95 (7.77, 9.50)) in comparison to those with a disease duration of ≤2 years, p<0.05. Among patients with a disease duration surpassing 2 years, those with higher HbA1C levels exhibited lower E/A values (0.80 (0.70, 0.90) vs. (0.85 (0.75, 1.10)) and higher E/e' values (11.00 (9.87, 12.15) vs. 9.80 (9.20, 10.80)) in contrast to patients with low HbA1C levels, p<0.05. Multiple linear regression analysis identified HbA1C (β=0.294, p<0.001) and disease duration (β=0.319, p<0.001) as independent risk factors for the E/A value in diabetes patients. Furthermore, HbA1C (β=0.178, p=0.015) and disease duration (β=0.529, p<0.001) emerged as independent risk factors for the E/e' value in diabetic patients.

Conclusions

In individuals with T2DM exhibiting preserved ejection fraction, the presence of left ventricular diastolic dysfunction is significantly associated with HbA1C levels and the duration of diabetes.

The effect of physical activity level on the severity of diastolic dysfunction

BACKGROUND

Diastolic dysfunction (DD) is a risk factor for cardiovascular events in patients undergoing non-cardiac surgeries. Investigators aimed to assess the effect of physical activity level on the diastolic function of the left ventricle (LV) in patients attending the preoperative visit.

METHODS

This analytic cross-sectional study was conducted on 228 patients referred to Poursina hospital from November 2021 to March 2022. To define the physical activity level, we used the short form of the International Physical Activity Questionnaire (IPAQ). We categorized patients into inactive, minimally active, and health-enhancing physical activity groups. We also divided participants into three groups based on their daily sitting time. Also, echocardiographic parameters were calculated. The diastolic function of LV was evaluated, and its grading was defined from mild (grade1) to severe (grade 3).

RESULTS

Results showed that patients with DD had significantly higher age and lower levels of education (P < 0.001 and P = 0.005, respectively). After assessing echocardiographic parameters, we found that E/e', TR Velocity, left atrial volume index, and pulmonary artery pressure had a statistically significant inverse relationship with physical activity level (P < 0.001 for all). Comparing physical activity level of subgroups showed that in HEPA (health-enhancing physical activity), the chance of developing grade 2 or 3 DD was reduced by 97% compared to the inactive group (OR = 0.03, P < 0.001). Still, there was no significant difference between the inactive and minimally active groups (P = 0.223).

CONCLUSIONS

This study showed an inverse relationship between physical activity level and DD of the LV in a sample of 228 individuals attending the Anesthesia Clinic, independent of potentially confounding variables.Therefore, due to lower rate of DD in patients who are physically active, we can expect lower occurrence rate of cardiovascular events during surgery.

Cardiac function and exercise capacity in patients with metabolic syndrome: A cross-sectional study

Background

Metabolic syndrome is a pre-diabetes condition that is associated with increased cardiovascular morbidity and mortality. We aimed to explore how exercise capacity, cardiac structure, and function were affected in patients with metabolic syndrome.

Methods

Outpatients with echocardiography and exercise stress test combined with impedance cardiography (ETT + ICGG) results available from Nov 2018 to Oct 2020 were retrospectively enrolled. Echocardiographic, ETT + ICG profiles, and exercise performance were compared between patients with metabolic syndrome and the ones without. Sensitivity analyses were performed excluding patients without established coronary heart disease and further 1:1 paired for age and gender, respectively. Multiple linear regression was used to find out related predictors for maximal metabolic equivalents (METs).

Results

Three hundred and twenty-third patients were included, among whom 97 were diagnosed as metabolic syndrome. Compared to patients without metabolic syndrome, echocardiography showed that patients with metabolic syndrome had a significantly lower E/A ratio (p &lt; 0.001). Besides, they have larger left atrium, larger right ventricle, and thicker interventricular septum (all p &lt; 0.001), but similar left ventricular ejection fraction (P = 0.443). ICG showed that patients with metabolic syndrome had significantly higher stroke volume at rest and maximum (p &lt; 0.001), higher left cardiac work index at rest and maximum (p = 0.005), higher systemic vascular resistance (SVR) at rest (p &lt; 0.001), but similar SVI (p = 0.888). During exercise, patients with metabolic syndrome had lower maximal METs (p &lt; 0.001), and a higher proportion suffering from ST-segment depression during exercise (p = 0.009). Sensitivity analyses yielded similar results. As for the linear regression model, 6 independent variables (systolic blood pressure, BMI, E/A ratio, the height of O wave, the peak value of LCWi, and the baseline of SVR) had statistically significant effects on the maximal METs tested in exercise (R = 0.525, R2 = 0.246, P &lt; 0.001).

Conclusion

Patients with metabolic syndrome had significant structural alteration, apparent overburden of left ventricular work index, pre-and afterload, which may be the main cause of impaired exercise tolerance.

Association between metabolic syndrome and left ventricular geometric change including diastolic dysfunction

BACKGROUND

We investigated the association between individual components of metabolic syndrome (MetS) and left ventricular (LV) geometric changes, including diastolic dysfunction, in a large cohort of healthy individuals.

METHODS

Overall, 148 461 adults who underwent echocardiography during a health-screening program were enrolled. Geographic characteristics on echocardiography and several markers of LV relaxation function were identified according to individual MetS components. Univariate linear regression analysis and a multivariate regression model adjusted for factors known to influence LV relaxation function were conducted.

RESULTS

The prevalence of LV diastolic dysfunction (LVDD) was higher in the MetS group than in the non-MetS group (0.56% vs. 0.27%, p < .001). In univariate and multivariate analyses, E/A ratio, e' velocity, and left atrial volume index were significantly associated with each component of MetS and covariates (all p ≤ .001). In the age- and sex-adjusted model, MetS was significantly associated with LVDD (odds ratio [95% confidence interval], 1.350 [1.103, 1.652]). However, subjects with more MetS components did not have a significantly higher risk of LVDD. As the analysis was stratified by sex, the multivariate regression model showed that MetS was significantly associated with LVDD only in men (1.3 [1.00, 1.68]) with higher risk in more MetS component (p for trend < .001). In particular, triglyceride (TG) and waist circumference (WC) among MetS components were significantly associated with LVDD in men.

CONCLUSIONS

MetS was associated with the risk of LVDD, especially in men, with a dose-dependent association between an increasing number of components of MetS and LVDD. TG and WC were independent risk factors for LVDD in men.

The effect of overweight/obesity on diastolic function in children and adolescents: A meta-analysis

Left ventricular diastolic function (LVDF) is an important marker of early cardiovascular remodelling, which has not been well summarized in young people with overweight/obesity. Weighted, random-effects regression was used to determine the strength of associations of both body mass index (BMI) and homeostatic model assessment of insulin resistance (HOMA-IR) with LVDF measures, adjusting for age and sex. Six databases were searched after PROSPERO registration (CRD42020177470) from inception to July 2020 for studies that compared LVDF between overweight/obesity and control groups aged ≤24 years, yielding 70 studies (9983 individuals). Quality and risk of bias were assessed using NHLBI tools, with scores of good, fair, and poor for 6, 48, and 16 studies, respectively. Increased BMI was associated with worse LVDF in all measures except early mitral inflow deceleration time, with septal early diastolic tissue peak velocity to late diastolic tissue peak velocity ratio having the strongest association (n = 13 studies, 1824 individuals; r = -0.69; P < 0.001). Elevated HOMA-IR was also associated with worse LVDF. Although we could not determine the causality of reduced LVDF in young people, our findings should aid the development of paediatric guidelines for the assessment of LVDF and support further work to address the longitudinal consequences of childhood obesity and IR on LVDF.

Caloric restriction in heart failure: A systematic review

BACKGROUND AND AIMS

Nutrition exerts a determinant role in maintaining cardiac function, regulating insulin and mitochondrial efficiency, that are essential to support energy production for contractility. In patients with heart failure (HF), myocardial tissue efficiency is reduced because of decreased mitochondrial oxidative capacity. In HF conditions, cardiomyocytes shift toward glucose and a reduction in fatty acid utilization. Calorie restriction induces weight loss in obese patients and can be beneficial in some HF patients, although this has generated some controversy. This study aims to evaluate the impact of the CR diet on myocardial efficiency in HF patients.

METHODS

On Pubmed and Embase, articles related to the keywords: "chronic heart failure" with "diet," "nutrition," "insulin resistance," and "caloric restriction" have been searched, Studies, including exercise or food supplementation, were excluded.

RESULTS

The retrieved articles showed that weight loss, through the activation of insulin and various kinase pathways, regulates the efficiency of myocardial tissue. In contrast, insulin resistance represents a strong cardiovascular risk factor that reduces myocardial function.

CONCLUSION

CR diet represents the first therapy in overweight HF patients, both with preserved ejection fraction (HFpEF) and with reduced ejection fraction (HFrHF) because reducing body fat, the myocardial function increased. Insulin activity is the critical hormone that regulates mitochondrial function and cardiac efficiency. However, a severely restricted diet may represent a severe risk factor correlated with all-cause mortality, particularly in underweight HF patients. Long-term studies conducted on large populations are necessary to evaluate the effects of CR on myocardial function in HF patients.

Metabolic Risk Factors and Left Ventricular Diastolic Function in Middle-Aged Chinese Living in the Tibetan Plateau

Background

Data regarding the metabolic risk factors clustering on the risk of left ventricular diastolic dysfunction (LVDD) are lacking among people living at high altitude and under hypoxic conditions. In this study, we explored the association between metabolic risk factor clustering and LVDD among the Tibetan population of China.

Methods and Results

We conducted a cross‐sectional survey in a representative sample of 1963 Tibetans in 2014 to 2016. Grading LVDD was based on recommendations for the evaluation of LV diastolic function by echocardiography (2009). The prevalence of LVDD among 1963 participants (mean age: 51.51 years, 41.11% male) was 34.39%. Odds ratios (95% CI) of LVDD for the 1, 2, and 3 to 5 risk factors clustering were 1.45 (0.96–2.17), 2.68 (1.8–3.98), and 2.9 (1.9–4.43), respectively (P for trend <0.001). The association between metabolic risk factors clustering and LVDD was much more pronounced in the middle‐aged group than in the elderly (P for interaction=0.0170). High altitude was one of the major independent risk factors for LVDD; however, habitation altitude had no significant effect on the association between metabolic risk factors and LVDD (P for interaction=0.1022). The multivariable dominance analysis indicated that abdominal obesity, hypertension, and elevated blood glucose were the significant contributors to LVDD.

Conclusions

There was a significant positive association between the metabolic risk factor clustering number and LVDD among a population living at high altitude, especially in middle‐aged adults. However, habitation altitude itself has no significant effect on the association between metabolic risk factors and LVDD.

Different Patterns of Left Ventricular Hypertrophy in Metabolically Healthy and Insulin-Resistant Obese Subjects

Obese subjects showed different cardiovascular risk depending by different insulin sensitivity status. We investigated the difference in left ventricular mass and geometry between metabolically healthy (MHO) and unhealthy (MUHO) obese subjects. From a cohort of 876 obese subjects (48.3 ± 14.1 years) without cardio-metabolic disease and stratified according to increasing values of Matsuda index after 75 g oral glucose tolerance test, we defined MHO (n = 292) those in the upper tertile and MUHO (n = 292) those in the lower tertile. All participants underwent echocardiographic measurements. Left ventricular mass was calculated by Devereux equation and normalized by height^2,7 and left ventricular hypertrophy (LVH) was defined by values >44 g/m^2.7 for females and >48 g/m^2.7 for males. Left ventricular geometric pattern was defined as concentric or eccentric if relative wall thickness was higher or lower than 0.42, respectively. MHO developed more commonly a concentric remodeling (19.9 vs. 9.9%; p = 0.001) and had a reduced risk for LVH (OR 0.46; p < 0.0001) than MUHO, in which the eccentric type was more prevalent (40.4 vs. 5.1%; p < 0.0001). We demonstrated that obese subjects-matched for age, gender and BMI-have different left ventricular mass and geometry due to different insulin sensitivity status, suggesting that diverse metabolic phenotypes lead to alternative myocardial adaptation.

[Relationship of sarcopenic obesity with left ventricular diastolic dysfunction in elderly patients with diabetes]

AIM

This study aimed to examine the relationship of obesity, sarcopenia, and sarcopenic obesity (SO) with left ventricular diastolic dysfunction (LVDD) in elderly patients with diabetes.

METHODS

Subjects included in this study were patients with diabetes ≥65 years of age and who were receiving treatment on an outpatient basis at the Ise Red Cross Hospital. To determine the presence of LVDD, we divided the early diastolic left ventricular filling velocity (E) by the early mitral annular motion velocity (E') (E/E'), which was measured using tissue Doppler imaging. To evaluate sarcopenia, SARC-F-J, a self-administered questionnaire consisting of five items, was used. Obesity was defined as a body mass index >25. Using a multiple logistic regression analysis with LVDD as the dependent variable and sarcopenia, obesity, and SO as explanatory variables, we calculated the odds ratios of LVDD for each variable.

RESULTS

The subjects were 291 (157 male and 134 female) patients. Among male patients, the odds ratios after moderating for LVDD in the sarcopenia, obese, and SO groups were 0.82 (95% confidence interval [CI) ], 0.20 to 3.27, P=0.784), 1.92 (95% CI, 0.69 to 5.32, P=0.207), and 6.41 (95% CI, 1.43 to 28.53, P=0.015), respectively, whereas among female patients, these ratios were 1.31 (95% CI, 0.31 to 5.51, 0.708), 1.41 (95% CI, 0.45 to 4.37, P=0.551), and 3.18 (95% CI, 0.93 to 10.9, P=0.064), respectively.

CONCLUSIONS

In male elderly patients with diabetes, SO was significantly correlated with LVDD. We believe that it is important to consider LVDD when examining male elderly patients with SO.

Dysglycemia and increased left ventricle mass in normotensive patients admitted with a first myocardial infarction: prognostic implications of dysglycemia during 14 years of follow-up

Background

Left ventricle mass (LVM) can be influenced by various conditions including hypertension and/or inherent cardiomyopathies. Dysglycemia is also thought to exert an anabolic effect on heart tissue by hyperinsulinemia and thereby promoting increased LVM. The primary aim of this study was to assess the influence of dysglycemia on LVM evaluated by an oral glucose tolerance test (OGTT) in patients admitted with a first myocardial infarction (MI) without hypertension. The secondary aim was to assess the impact of dysglycemia on major adverse cardiovascular events (MACE) and all-cause mortality during long-term follow-up.

Methods

Patients admitted with a first MI without known history of hypertension were included. All patients without previously known type 2 diabetes mellitus (T2DM) had a standardized 2-hour OGTT performed and were categorized as: normal glucose tolerance (NGT), impaired fasting glucose (IFG)/impaired glucose tolerance (IGT) and newly detected T2DM (new T2DM). LVM was measured by echocardiography using Devereaux formula and indexed by body surface area. Multivariate linear regression analysis was used to assess the impact of confounders (dysglycemia by OGTT, known T2DM, age, sex and type of MI) on LVM. Cox proportional hazard model was used to assess the impact of dysglycemia on all-cause mortality and a composite endpoint of MACE (all-cause mortality, MI, revascularisation due to stable angina, coronary artery bypass graft, ischemic stroke or hemorrhagic stroke).

Results

Two-hundred-and-five patients were included and followed up to 14 years. In multivariate regression analysis, LVM was only significantly increased in patients categorized as new T2DM (β = 25.3; 95% CI [7.5–43.0]) and known T2DM (β = 37.3; 95% CI [10.0-64.5]) compared to patients with NGT. Patients with new T2DM showed higher rates of MACE and all-cause mortality compared to patients with IFG/IGT and NGT; however no significantly increased hazard ratio was detected.

Conclusions

Dysglycemia is associated with increasing LVM in normotensive patients with a first acute myocardial infarction and the strongest association was observed in patients with new T2DM and patients with known T2DM. Dysglycemia in normotensive patients with a first MI is not an independent predictor of neither MACE nor all-cause mortality during long-term follow-up compared to normotensive patients without dysglycemia.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1084-5) contains supplementary material, which is available to authorized users.

Determinants of left ventricular diastolic function-The Cardiovascular Risk in Young Finns Study

Decreased left ventricular (LV) diastolic function is associated with increased all-cause mortality and risk for a heart failure. The determinants of LV diastolic function have been mainly studied in elderly populations; however, the origin of LV heart failure may relate to the lifestyle factors acquired during the life course. Therefore, we examined biochemical, physiological, and lifestyle determinants of LV diastolic function in 34-49-year-old participants of the Cardiovascular Risk in Young Finns Study (Young Finns Study). In 2011, clinical examination and echocardiography were performed for 1928 participants (880 men and 1048 women; aged 34-49 years). LV diastolic function was primarily defined using E/é-ratio (population mean 4.8, range 2.1-9.0). In a multivariate model, systolic blood pressure (P < 0.005), female sex (P < 0.005), age (P < 0.005), waist circumference (P = 0.024), smoking (P = 0.028), serum alanine aminotransferase (P = 0.032) were directly associated with E/é-ratio, while an inverse association was found for height (P < 0.005). Additionally, a higher E/é-ratio was found in participants with concentric hypertrophy compared to normal cardiac geometry (P < 0.005). Other indicators of the LV diastolic function including E/A-ratio and left atrial volume index showed similarly strong associations with systolic blood pressure and age. In conclusion, we identified systolic blood pressure, waist circumference and smoking as modifiable determinants of the LV diastolic function in the 34-49-year-old participants of the Young Finns Study.

Dietary intervention with a specific micronutrient combination for the treatment of patients with cardiac arrhythmias: the impact on insulin resistance and left ventricular function

Background

Cardiac arrhythmias (CA) are very common and may occur with or without heart disease. Causes of these disturbances can be components of the metabolic syndrome (MetS) or deficits of micronutrients especially magnesium, potassium, B vitamins and coenzyme Q10. Both causes may also influence each other. Insulin resistance (IR) is a risk factor for diastolic dysfunction. One exploratory outcome of the present pilot study was to assess the impact of a dietary intervention with specific micronutrients on the lowering of IR levels in patients with CA with the goal to improve the left ventricular (LV) function.

Methods

This was a post hoc analysis of the randomized double blind, placebo-controlled pilot study in patients with CA (VPBs, SVPBs, SV tachycardia), which were recruited using data from patients who were 18–75 years of age in an Outpatient Practice of Cardiology. These arrhythmias were assessed by Holter ECG and LV function by standard echocardiography. Glucose metabolism was measured by fasting glucose, fasting insulin level and the Homeostasis Model Assessment of IR (HOMA-IR) at baseline and after 6 weeks of dietary supplementation.

Results

A total of 54 randomized patients with CA received either a specific micronutrient combination or placebo. Dietary intervention led to a significant decrease in fasting insulin ≥58 pmol/l (p = 0.020), and HOMA-IR (p = 0.053) in the verum group after 6 weeks. At the same time, parameters of LV diastolic function were improved after intervention in the verum group: significant reduction of LV mass index (p = 0.003), and in tendency both a decrease of interventricular septal thickness (p = 0.053) as well as an increase of E/A ratio (p = 0.051). On the other hand, the premature beats (PBs) were unchanged under verum.

Conclusions

In this pilot study, dietary intervention with specific micronutrient combination as add-on to concomitant cardiovascular drug treatment seems to improve cardio metabolic health in patients with CA. Further studies are required.

Study registration

The study was approved by the Freiburg Ethics Commission International and was retrospectively registered with the U.S. National Institutes of Health Clinical Trials gov ID NCT 02652338 on 16 December 2015.

Impact of Nutrition on Cardiovascular Function

The metabolic sources of energy for myocardial contractility include mainly free fatty acids (FFA) for 95%, and in lesser amounts for 5% from glucose and minimal contributions from other substrates such lactate, ketones, and amino acids. However, myocardial efficiency is influenced by metabolic condition, overload, and ischemia. During cardiac stress, cardiomyocytes increase glucose oxidation and reduce FFA oxidation. In patients with ischemic coronary disease and heart failure, the low oxygen availability limits myocardial reliance on FFA and glucose utilization must increase. Although glucose uptake is fundamental to cardiomyocyte function, an excessive intracellular glucose level is detrimental. Insulin plays a fundamental role in maintaining myocardial efficiency and in reducing glycemia and inflammation; this is particularly evident in obese and type-2 diabetic patients. An excess of F availability increase fat deposition within cardiomyocytes and reduces glucose oxidation. In patients with high body mass index, a restricted diet or starvation have positive effects on cardiac metabolism and function while, in patients with low body mass index, restrictive diets, or starvation have a deleterious effect. Thus, weight loss in obese patients has positive impacts on ventricular mass and function, whereas, in underweight heart failure patients, such weight reduction adds to the risk of heart damage, predisposing to cachexia. Nutrition plays an essential role in the evolution of cardiovascular disease and should be taken into account. An energy-restricted diet improves myocardial efficiency but can represent a potential risk of heart damage, particularly in patients affected by cardiovascular disease. Micronutrient integration has a marginal effect on cardiovascular efficiency.

Physical activity and impaired left ventricular relaxation in middle aged adults

The aim of this study was to examine the relationship between physical activity level and impaired left ventricular (LV) relaxation in a large sample of apparently healthy men and women. We conducted a cross-sectional study in 57,449 adults who underwent echocardiography as part of a comprehensive health examination between March 2011 and December 2014. Physical activity level was assessed using the Korean version of the International Physical Activity Questionnaire Short Form. The presence of impaired LV relaxation was determined based on echocardiographic findings. Physical activity levels were inversely associated with the prevalence of impaired LV relaxation. The multivariable-adjusted odds ratios (95% confidence interval) for impaired LV relaxation comparing minimally active and health-enhancing physically active groups to the inactive group were 0.84 (0.77–0.91) and 0.64 (0.58–0.72), respectively (P for trend < 0.001). These associations were modified by sex (p for interaction <0.001), with the inverse association observed in men, but not in women. This study demonstrated an inverse linear association between physical activity level and impaired LV relaxation in a large sample of middle-aged Koreans independent of potential confounders. Our findings suggest that increasing physical activity may be independently important in reducing the risk of impaired LV relaxation.

Association of Age at Menarche With Left Ventricular Diastolic Dysfunction in Middle-Aged Women

BACKGROUND

There is sparse research on whether if early menarche is related to left ventricular (LV) diastolic dysfunction. The present study examined this relationship in Korean women.

METHODS AND RESULTS

In a cross-sectional study we analyzed the records of 18,910 Korean women (≥30 years) who underwent echocardiography as part of a comprehensive health examination. Age at menarche was assessed using standardized, self-administered questionnaires. Presence of LV diastolic dysfunction was determined from the echocardiographic findings. Of the 18,910 women, 3,449 had LV diastolic dysfunction. Age at menarche was inversely associated with prevalence of LV diastolic dysfunction. In a multivariable-adjusted model, odds ratios (95% confidence interval) for LV diastolic dysfunction comparing menarche age to menarche at 15-18 years were 1.77 (1.38-2.27) for <12 years, 1.31 (1.11-1.54) for 12 years, 1.26 (1.11-1.43) for 13 years, and 1.03 (0.91-1.15) for 14 years (P for trend <0.001). Adjusting for body mass index or percent fat mass partially reduced these associations.

CONCLUSIONS

This large study found an inverse relationship between menarche age and LV diastolic dysfunction. Future prospective studies are needed to investigate potential causal relationships.

Oxidative Stress and Cardiovascular Risk: Obesity, Diabetes, Smoking, and Pollution: Part 3 of a 3-Part Series

Oxidative stress occurs whenever the release of reactive oxygen species (ROS) exceeds endogenous antioxidant capacity. In this paper, we review the specific role of several cardiovascular risk factors in promoting oxidative stress: diabetes, obesity, smoking, and excessive pollution. Specifically, the risk of developing heart failure is higher in patients with diabetes or obesity, even with optimal medical treatment, and the increased release of ROS from cardiac mitochondria and other sources likely contributes to the development of cardiac dysfunction in this setting. Here, we explore the role of different ROS sources arising in obesity and diabetes, and the effect of excessive ROS production on the development of cardiac lipotoxicity. In parallel, contaminants in the air that we breathe pose a significant threat to human health. This paper provides an overview of cigarette smoke and urban air pollution, considering how their composition and biological effects have detrimental effects on cardiovascular health.

Relationship Between γ-Glutamyltransferase Levels and Left Ventricular Diastolic Dysfunction

BACKGROUND

The goal of this study was to examine the association of serum γ-glutamyltransferase (GGT) levels with left ventricular (LV) diastolic dysfunction and LV hypertrophy.

METHODS AND RESULTS

A cross-sectional study of 79,459 Korean men and women who underwent an echocardiography as part of a comprehensive health examination between March 2011 and December 2014. The presence of LV diastolic dysfunction and LV hypertrophy was determined using echocardiography. Of the subjects, 5,447 had LV diastolic dysfunction and 2,070 had LV hypertrophy. Both LV diastolic dysfunction and LV hypertrophy were associated with higher levels of serum GGT. Multivariable-adjusted odds ratios (95% confidence interval) for LV diastolic dysfunction comparing serum GGT quartiles 2-4 with quartile 1 were 1.25 (1.08-1.44), 1.65 (1.43-1.91) and 2.23 (1.92-2.58), respectively (P for trend <0.001). Multivariable-adjusted odds ratios (95% CI) for LV hypertrophy comparing serum GGT quartiles 2-4 with quartile 1 were 1.13 (0.94-1.36), 1.14 (0.93-1.40) and 1.33 (1.07-1.65), respectively (P for trend 0.01). These associations of serum GGT levels with LV diastolic dysfunction and LV hypertrophy were modified by age (P for interaction <0.05).

CONCLUSIONS

This study demonstrated a positive association between serum GGT levels and LV diastolic dysfunction and LV hypertrophy in a large cohort of middle-aged men and women independent of potential confounders.

The relationship between insulin sensitivity and heart rate-corrected QT interval in patients with type 2 diabetes

BACKGROUND

Reduced insulin sensitivity not only contributes to the pathogenesis of type 2 diabetes but is also linked to multiple metabolic risk factors and cardiovascular diseases (CVD). A prolonged heart rate-corrected QT interval (QTc interval) is related to ventricular arrhythmias and CVD mortality and exhibits a high prevalence among type 2 diabetes patients. The aim of the study was to investigate the relationship between insulin sensitivity and the QTc interval in patients with type 2 diabetes.

METHODS

This cross-sectional observational study recruited 2927 patients with type 2 diabetes who visited the Affiliated Haian Hospital and Second Affiliated Hospital of Nantong University. The insulin sensitivity index (Matsuda index, ISI_Matsuda) derived from 75-g OGTT and other metabolic risk factors were examined in all patients. The QTc interval was estimated using a resting 12-lead electrocardiogram, and an interval longer than 440 ms was considered abnormally prolonged.

RESULTS

The QTc interval was significantly and negatively correlated with the ISI_Matsuda (r = -0.296, p < 0.001), and when the multiple linear regression analysis was adjusted for anthropometric parameters, metabolic risk factors, and current antidiabetic treatments, the QTc interval remained significantly correlated with the ISI_Matsuda (β = -0.23, t = -12.63, p < 0.001). The proportion of patients with prolonged QTc interval significantly increased from 12.1% to 17.9%, 25.6% and 37.9% from the fourth to third, second and first quartile of the ISI_Matsuda, respectively. After adjusting for anthropometric parameters by multiple logistic regression analysis, the corresponding odd ratios (ORs) for prolonged QTc interval of the first, second and third quartiles versus the fourth quartile of ISI_Matsuda were 3.11 (95% CI 2.23-4.34), 2.09 (1.51-2.88) and 1.53 (1.09-2.14), respectively, and p for trend was <0.001.

CONCLUSIONS

Reduced insulin sensitivity is associated with an increase in the QTc interval in patients with type 2 diabetes.

Bone mineral density is associated with left ventricular diastolic function in women

BACKGROUND

Low bone mineral density (BMD) and left ventricular (LV) diastolic function are associated with heart failure. However, little is known about the association between BMD and LV diastolic function.

HYPOTHESIS

BMD is independently related to LV diastolic function in women.

METHODS

We conducted a cross-sectional study of 432 women. Brachial-ankle pulse wave velocity (baPWV) and BMD measurements were performed. LV diastolic function and structure were assessed by echocardiographic examination.

RESULTS

BaPWV and the percentage of LV diastolic dysfunction increased with progressive bone loss. Moreover, partial correlation analysis demonstrated that BMD at spine L2-4 and at femoral neck were correlated with baPWV and LV diastolic function parameters after adjusting covariates. Multivariate logistic regression analysis revealed that osteoporosis was independently associated with LV diastolic dysfunction in women.

CONCLUSIONS

Osteoporosis is independently associated with LV diastolic dysfunction in women. A prospective study is needed to elucidate the effects of BMD on cardiac function in women.

Association of serum calcium and heart failure with preserved ejection fraction in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a recognized trigger factor for heart failure with preserved ejection fraction (HFpEF). Recent studies show that higher serum calcium level is associated with greater risk of both T2DM and heart failure. We speculate that increased serum calcium is related to HFpEF prevalence in patients with T2DM.

METHODS

In this cross-sectional echocardiographic study, 807 normocalcemia and normophosphatemia patients with T2DM participated, of whom 106 had HFpEF. Multinomial logistic regression was carried out to determine the variables associated with HFpEF. The associations between serum calcium and metabolic parameters, as well as the rate of HFpEF were examined using bivariate linear correlation and binary logistic regression, respectively. The predictive performance of serum calcium for HFpEF was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

Patients with HFpEF have significantly higher serum calcium than those without HFpEF. Serum calcium was positively associated with total cholesterol, triglycerides, low-density lipoprotein cholesterol, serum uric acid, HOMA-IR and fasting plasma glucose. Compared with patients in the lowest serum calcium quartile, the odds ratio (OR) for HFpEF in patients in the highest quartile was 2.331 (95 % CI 1.088-4.994, p = 0.029). When calcium was analyzed as a continuous variable, per 1 mg/dL increase, the OR (95 % CI) for HFpEF was [2.712 (1.471-5.002), p = 0.001]. Serum calcium can predict HFpEF [AUC = 0.673, 95 % CI (0.620-0.726), p < 0.001].

CONCLUSIONS

An increase in serum calcium level is associated with an increased risk of HFpEF in patients with T2DM.

Cardiometabolic Syndrome and Increased Risk of Heart Failure

Approximately 50 % of patients with heart failure have diastolic heart failure (HFPEF) with the major predisposing risk factors age, inactivity, obesity, insulin resistance (IR), type-2 diabetes, and hypertension. The prognosis of HFPEF is comparable to that of systolic heart failure, but without any specific or effective treatment. This review presents a biomathematically corrected diagnostic approach for quantification of diastolic dysfunction (DD) via the age dependency of diastolic function. Pathophysiological mechanisms for DD in the cardiometabolic syndrome (CMS) are mainly based on downstream effects of IR including insufficient myocardial energy supply. The second section discusses therapeutic strategies for the control and therapy of CMS, IR, and the associated DD/HFPEF with a focus on dietary therapy that is independent of weight loss but improves all manifestations of the CMS and reduces cardiovascular risk.

Effects of analogue insulin in multiple daily injection therapy of type 2 diabetes on postprandial glucose control and cardiac function compared to human insulin: a randomized controlled long-term study

Background

The prevention of cardiovascular disease, including diastolic cardiac dysfunction with its high prevalence and ominous prognosis, is a therapeutic challenge for patients with type 2 diabetes. Both short and long-acting insulin analogues (AI) have been shown to reduce glucose variability and provide potential benefit for cardiovascular disease although the effects on cardiac function have not yet been evaluated. This long-term, prospective, randomized controlled trial in patients with type 2 diabetes (T2D) tested the hypothesis that a multiple daily injection regimen (MDI) with AI improves postmeal glucose excursions in comparison to human insulin (HI) and that the effects of AI improve diastolic cardiac function.

Methods

For 36 months, MDI treatment in 109 T2D patients was adapted every 3 months (targets: fasting glucose ≤ 110 mg/dl, postmeal glucose ≤ 150 mg/dl) in both groups: AI (insulin detemir and insulin aspart, n = 61) and HI (NPH-insulin and regular HI, n = 48). Diastolic cardiac function (myocardial velocity E’ using tissue Doppler imaging and the mitral inflow ratio E/A) and vascular function were assessed before and 2 h after a standardized breakfast (48 g carbohydrates). At baseline, both groups were comparable with regards to demographic, cardiac and metabolic data. Analysis of data included traditional statistics as well as the use of a multiple imputation technique shown in brackets [ ].

Results

At 36 months, the primary endpoint, postmeal glucose, decreased by 20 ± 62 mg/dl, p = 0.038 [p = 0.021] with AI and increased insignificantly with HI (inter-group p = 0.032 [p = 0.047]) to postmeal glucose levels of 161 ± 39 with AI vs. 195 ± 54 mg/dl with HI (inter-group p = 0.002 [p = 0.010]) whereas the levels of fasting glucose and HbA1c were comparable. With AI, postmeal E’ improved by 0.6 ± 1.4 cm/s, p = 0.009 [p = 0.002] and fasting E’ by 0.4 ± 1.4 cm/s, p = 0.069 [p = 0.013], however, E’ remained unchanged with HI. These changes were consistent with those of the traditional parameter E/A.

Conclusions

MDI with AI results in better postmeal glucose control compared to HI. The treatment with AI is associated with improved diastolic cardiac function.

ClinicalTrials.gov (NTC00747409)

Greater body mass index is a better predictor of subclinical cardiac damage at long-term follow-up in men than is insulin sensitivity: a prospective, population-based cohort study

BACKGROUND

To examine whether lower insulin sensitivity as determined by homeostatic model assessment (HOMA-%S) was associated with increased left ventricular mass (LVM) and presence of LV diastolic dysfunction at long-term follow-up, independently of body mass index (BMI), in middle-aged, otherwise healthy males.

METHODS

Prospective population-based cohort study with a median (IQR) follow-up time of 28 (27-28) years, in which traditional cardiovascular risk factors, including HOMA-%S and BMI, were assessed at baseline, and echocardiographic determination of LVM and LV diastolic function was performed at follow-up. Associations between risk factors and echocardiographic variables were tested using multivariable linear and binary logistic regression.

RESULTS

The study population comprised 247 men with a median (IQR) age of 47 (47-48) years. Mean (SD) BMI was 25.1 +/- 3.0 kg/m(2), and median (IQR) HOMA-%S was 113.0 (68.3-284.6). Subjects with low insulin sensitivity (lowest HOMA-%S quartile (Q1)) had significantly greater BMI, fasting plasma insulin, and higher fasting blood glucose (FBG) (p <0.02 for all). BMI and HOMA-%S were significantly correlated (r = -0.383, p <0.0001). At follow-up, mean (SD) LVM and LVMI were 202 +/- 61 g and 103 +/- 31 g/m(2), respectively, whereas median (IQR) E/é was 10 (8-12). Moreover, 36 % had grade 2 or 3 diastolic dysfunction. In multivariable analyses, greater BMI, but not low insulin sensitivity was independently associated with later detection of increased LVM and diastolic dysfunction.

CONCLUSION

Greater baseline BMI, but not lower insulin sensitivity was independently associated with greater LVM and diastolic dysfunction at long-term follow-up.

Serum uric acid is associated with cardiac diastolic dysfunction among women with preserved ejection fraction

Serum uric acid (SUA) is associated with the severity and prognosis of systolic heart failure. We investigated the potential association between SUA and cardiac diastolic dysfunction among total of 744 cardiac patients (202 women and 542 men) who had preserved left ventricular ejection fraction. Presence of diastolic dysfunction was assessed by echocardiographic data, plasma B-type natriuretic peptide concentration, and left ventricular hypertrophy. Univariate analysis showed that the prevalence of diastolic dysfunction increased with increasing SUA value in women, but not in men. When sex-nonspecific SUA quartiles were used, multivariate logistic regression analysis, among female patients who were not taking uric acid lowering medication, showed that the third (SUA, 5.7-6.4 mg) and the fourth (SUA, ≥6.5 mg/dl) SUA quartiles were associated with diastolic dysfunction with an odds ratio of 3.25 (P < 0.05) and 8.06 (P < 0.001), respectively, when compared with the first SUA quartile (≤4.7 mg/dl). When sex-specific SUA quartiles were used among these population, multivariate logistic regression analysis showed that the fourth SUA quartile (≥5.7 mg/dl) was associated with diastolic dysfunction with an odds ratio of 5.34 (P < 0.05) when compared with the first SUA quartile (≤4.1 mg/dl). By contrast, the relationship between SUA and diastolic dysfunction was not significant in men, irrespective of which of the sex-nonspecific or sex-specific SUA quartiles were used. These data indicated that among cardiac patients with preserved ejection fraction, SUA was significantly associated with diastolic dysfunction in women but not in men.

Preclinical Systolic and Diastolic Dysfunctions in Metabolically Healthy and Unhealthy Obese Individuals

BACKGROUND

Despite the substantial overlap of obesity and metabolic disease, there is heterogeneity with respect to cardiovascular risk. We sought to investigate preclinical differences in systolic and diastolic function in obesity, and specifically compare obese individuals with and without metabolic syndrome (MS).

METHODS AND RESULTS

Obese individuals without cardiac disease with (OB/MS+, n=124) and without (OB/MS-, n=37) MS were compared with nonobese controls (n=29). Diastolic function was assessed by transmitral and tissue Doppler. Global longitudinal strain (LS) and time-based dyssynchrony were assessed by speckle tracking. Both OB/MS- and OB/MS+ groups had similar ejection fraction but worse systolic mechanics as assessed by LS and dyssynchrony when compared with nonobese controls. Specifically, OB/MS- had 2.5% lower LS (SE, 0.7%; P=0.001 in multivariable-adjusted analyses) and 10.8 ms greater dyssynchrony (SE, 3.3 ms; P=0.002), and OB/MS+ had 1.0% lower LS (SE, 0.3%; P<0.001) and 7.8 ms greater dyssynchrony (SE, 1.5 ms; P<0.001) when compared with controls. Obesity was associated with impaired diastolic function regardless of MS status, as evidenced by greater left atrial diameter and left ventricular mass although diastolic dysfunction was more pronounced in OB/MS+ than in OB/MS- individuals.

CONCLUSIONS

Obesity is associated with subclinical differences in both systolic and diastolic function regardless of the presence or absence of MS although MS seems to be associated with worse diastolic dysfunction. When compared with controls, metabolically healthy obese had lower LS, greater dyssynchrony, and early diastolic dysfunction, supporting the notion that obesity per se may have adverse cardiovascular effects regardless of metabolic disease.

Combination of hyperuricemia and metabolic syndrome is an independent and powerful predictor for left ventricular hypertrophy in rural Chinese

OBJECTIVES

To investigate the influence of MetS (metabolic syndrome) in combination with hyperuricemia on left ventricular hypertrophy (LVH) in residents in the rural area of Northeast China.

METHODS

We performed a cross-sectional baseline data analysis of 11,170 subjects (mean age: 54±11years) recruited from the rural area of China. Anthropometric indicators were measured according to standard methods. MetS was defined by the ATP III modified criteria. Hyperuricemia was defined according to sex-specific serum uric acid levels (SUA): SUA≥7.0mg/dL for male and≥6.0mg/dL for female. Four groups were listed: normouricemia non-MetS, hyperuricemia non-MetS, MetS normouricemia and hyperuricemia MetS.

RESULTS

Left ventricular mass index for height(2.7) (LVMH(2.7)) in female was significantly higher in hyperuricemia MetS group than that in normouricemia non-MetS (52.43±16.60 vs. 40.04±10.72g/m(2.7), P<0.001) group. Similar result was observed in men (48.93±13.17g/m(2.7) vs. 43.63±11.90g/m(2.7), P<0.001). The result of multiple regression analysis indicated that hyperuricemia MetS group had higher risk of LVH than other three groups (OR: 3.427 for female, P<0.001, OR: 1.987 for male, P<0.001). Moreover, female subjects in MetS normouricemia group [OR (95% CI): 2.313 (1.991-2.686)] had greater risk of LVH than that in hyperuricemia non-MetS group [OR (95% CI): 1.917 (1.166-3.151)]. Hyperuricemia non-MetS was found to be significantly and independently associated with LVH in women, but not in men.

CONCLUSION

Our study finds that the combination of hyperuricemia and MetS are independent and powerful predictor for LVH in rural area of Northeast Chinese. Women with MetS in combination with hyperuricemia have higher risk of LVH than men. It seems that MetS has greater effect on LVH than hyperuricemia does in women but not in men.

Metabolic syndrome is associated with atrial electrical and mechanical dysfunction

OBJECTIVE

In this study, we aimed to investigate the left atrial (LA) electrical and mechanical functions in patients with metabolic syndrome (MetS).

SUBJECTS AND METHODS

The study population consisted of 87 patients with MetS and 67 controls. Intra-atrial and interatrial electromechanical delays (EDs) were measured with tissue Doppler imaging. P-wave dispersion (Pd) was calculated from the 12-lead electrocardiograms. LA volumes were measured echocardiographically by the biplane area-length method.

RESULTS

Intra-atrial and interatrial EDs and Pd were significantly higher in patients with MetS (10.3 ± 6.3, 21.0 ± 11.5 and 41.7 ± 10.8) than in controls (7.4 ± 5.5, 12.3 ± 10.4 and 29.2 ± 7.4; p = 0.003, p < 0.001 and p < 0.001, respectively). The LA preatrial contraction volume and active emptying volumes were higher in this population, but the LA passive emptying fraction was lower. In the multivariate linear regression analysis, the presence of MetS, LA active emptying volume and left ventricular early diastolic (E) wave velocity/late diastolic (A) wave velocity (E/A) ratios were independent correlates of interatrial ED (p = 0.002, p = 0.001 and p = 0.025, respectively).

CONCLUSIONS

This study showed that intra-atrial and interatrial EDs and Pd were prolonged and LA mechanical functions were impaired in patients with MetS.

Quantification of diastolic dysfunction via the age dependence of diastolic function - impact of insulin resistance with and without type 2 diabetes

BACKGROUND

The alarming prevalence of heart failure with preserved ejection fraction requires quantification of diastolic dysfunction (DDF). Myocardial diastolic velocity E' implies that age is the most important determinant. We tested the hypothesis that age allows for quantification of DDF and assessment of the structural and metabolic determinants in patients with and without type 2 diabetes (D).

METHODS

This prospective, cross-sectional study assessed cardiovascular, metabolic and ultrasound data in 409 consecutive patients (Diabetes Center, Bogenhausen-Munich) between 20 and 90 years without known cardiac disease and either with (n=204) or without D but with common prevalence of cardiovascular risk factors, including a subgroup of healthy individuals (H, n=94).

RESULTS

In H, E' related to age as: E'norm=-0.163∗years+19.69 (R(2)=0.77, p<0.0001). According to this 1% reduction by annual physiologic aging, DDF was quantitated as E'-E' norm. Compared to nondiabetics, D patients were older, had greater BMI, lower E', more cardiovascular risk and greater DDF. In nondiabetics, grading of DDF by E-E'norm correlated with grading by filling pressure E/E'. Determinants of DDF by multivariate analysis included pulse wave velocity, diastolic blood pressure and the triglyceride/HDL ratio (a marker of insulin resistance) in nondiabetics and in D the same risk factors in reverse sequence and heart rate. Neither left atrial size nor left ventricular mass had significant impact.

CONCLUSIONS

The physiological impact of age on myocardial function consists of a 1% annual reduction in E' and enables precise quantification of diastolic dysfunction thereby unmasking the importance of metabolic risk for DDF.

Metabolic syndrome in hypertensive patients: An unholy alliance

For many years, it has been recognized that hypertension tends to cluster with various anthropometric and metabolic abnormalities including abdominal obesity, elevated triglycerides, reduced high-density lipoprotein cholesterol, glucose intolerance, insulin resistance and hyperuricemia. This constellation of various conditions has been transformed from a pathophysiological concept to a clinical entity, which has been defined metabolic syndrome (MetS). The consequences of the MetS have been difficult to assess without commonly accepted criteria to diagnose it. For this reason, on 2009 the International Diabetes Federation, the American Heart Association and other scientific organizations proposed a unified MetS definition. The incidence of the MetS has been increasing worldwide in parallel with an increase in overweight and obesity. The epidemic proportion reached by the MetS represents a major public health challenge, because several lines of evidence showed that the MetS, even without type 2 diabetes, confers an increased risk of cardiovascular morbidity and mortality in different populations including also hypertensive patients. It is likely that the enhanced cardiovascular risk associated with MetS in patients with high blood pressure may be largely mediated through an increased prevalence of preclinical cardiovascular and renal changes, such as left ventricular hypertrophy, early carotid atherosclerosis, impaired aortic elasticity, hypertensive retinopathy and microalbuminuria. Indeed, many reports support this notion, showing that hypertensive patients with MetS exhibit, more often than those without it, these early signs of end organ damage, most of which are recognized as significant independent predictors of adverse cardiovascular outcomes.

Role of autophagy in metabolic syndrome-associated heart disease

Metabolic syndrome is a constellation of multiple metabolic risk factors including abdominal obesity, glucose intolerance, insulin resistance, dyslipidemia and hypertension. Over the past decades, the prevalence of metabolic syndrome has increased dramatically, imposing a devastating, pandemic health threat. More importantly, individuals with metabolic syndrome are at an increased risk of diabetes mellitus and overall cardiovascular diseases. One of the common comorbidities of metabolic syndrome is heart anomalies leading to the loss of cardiomyocytes, cardiac dysfunction and ultimately heart failure. Up-to-date, a plethora of cell signaling pathways have been postulated for the pathogenesis of cardiac complications in obesity including lipotoxicity, inflammation, oxidative stress, apoptosis and sympathetic overactivation although the precise mechanism of action underscoring obesity-associated heart dysfunction remains elusive. Recent evidence has indicated a potential role of protein quality control in components of metabolic syndrome. Within the protein quality control system, the autophagy-lysosome pathway is an evolutionarily conserved pathway responsible for bulk degradation of large intracellular organelles and protein aggregates. Autophagy has been demonstrated to play an indispensible role in the maintenance of cardiac geometry and function under both physiological and pathological conditions. Accumulating studies have demonstrated that autophagy plays a pivotal role in the etiology of cardiac anomalies under obesity and metabolic syndrome. In this minireview, we will discuss on how autophagy is involved in the regulation of cardiac function in obesity and metabolic syndrome. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.

Is left ventricular diastolic dysfunction independent from presence of hypertension in metabolic syndrome? An echocardiographic study

BACKGROUND

It has been shown that left ventricular diastolic dysfunction (LVDD) develops in patients with metabolic syndrome (MetS). However, there is not sufficient evidence in the literature to determine whether this condition is due to increase in blood pressure, which is frequently encountered in MetS. The purpose of this study was to test the hypothesis whether LVDD in MetS is independent from the presence of hypertension.

METHODS

A total of 60 patients diagnosed with MetS and 30 healthy people, who were age- and gender-matched with the patient group, were included in the study as the control group. In the study group, 30 of the patients were normotensive whereas the other 30 had hypertension. Conventional echocardiographic examinations and tissue Doppler imaging were performed besides measurements of demographic and biochemical parameters.

RESULTS

In the hypertensive MetS group, early diastolic filling flow (E), early diastolic mitral annular velocity (E'), and E/A ratio were significantly lower compared to the control group. Late diastolic filling flow (A), deceleration time (DT), late diastolic mitral annular velocity (A'), and E/E' ratio were higher in the hypertensive MetS group than the control group. In the normotensive MetS group, E, E', and E/A ratio were also lower compared to the control group whereas DT, A', and E/E' ratio were higher.

CONCLUSION

These findings support the idea that LVDD may develop in patients with MetS even in the absence of hypertension. In addition, co-existence of hypertension with MetS contributes to further worsening of diastolic functions.

Association of epicardial fat with left ventricular diastolic function in subjects with metabolic syndrome: assessment using 2-dimensional echocardiography

Background

Metabolic syndrome (MetS) is related with left ventricular diastolic dysfunction (LVDD) and poor cardiovascular outcome. Epicardial adipose tissue (EAT) thickness, measured by echocardiography, is increased in subjects with MetS. However, the association of EAT with LV diastolic function has not been evaluated in subjects with MetS.

Methods

In this retrospective study, EAT thickness was measured in 1,486 consecutive asymptomatic patients with no known heart disease who had transthoracic echocardiography during a self-referred healthcare exam. Subjects with a history of ischemic heart disease, cardiomyopathy or significant valvular heart disease were excluded. LVDD was defined as E/e’ ratio ≥ 15. Subjects were grouped into two groups, those with MetS and those without.

Results

MetS was present in 346 subjects. There was no difference in LV systolic function between the two groups. However compared to patients without MetS, patients with MetS had larger left atrium (LA) size and higher E/e’ ratio (38 ± 5 versus 35 ± 5 mm for LA and 10.0 ± 3.3 versus 8.7 ± 2.7 for E/e’ ratio in subjects with versus without MetS both p < 0.001). LVDD was found in 27 (7.8%) subjects with MetS, compared to 30 (2.6%) subjects without MetS (p < 0.001). In subjects with MetS, EAT was significantly correlated with LVDD, even after adjusting for other cardiometabolic risk factors such as age, systolic blood pressure, BMI, blood glucose and LDL cholesterol (OR 1.845, 95% CI 1.153-2.951, p = 0.011).

Conclusion

Greater EAT is found in subjects with MetS. EAT is significantly associated with LVDD in subjects with MetS, even after adjusting for other risk factors.

Gender influence on left ventricular structure and function in metabolic syndrome. Are women at greater risk?

PURPOSE

The aim of this study was to investigate the influence of metabolic syndrome (MS) on left ventricular (LV) structure and function depending on gender.

METHODS

The study included 235 never-treated MS subjects and 138 controls. MS was defined as the presence of three or more National Cholesterol Education Program's Adult Treatment Panel III criteria. All the subjects underwent laboratory blood tests and complete two-dimensional, pulsed, and tissue Doppler echocardiography.

RESULTS

LV structure, diastolic function, and global function were significantly impaired in all MS subjects. Multivariate analysis of individual MS factors showed that increased blood pressure (BP) and impaired fasting glucose were independently associated with LV hypertrophy in women, whereas the only independent predictor in men was increased BP. The same analysis revealed that the combination of impaired glucose level, abdominal obesity, and dyslipidemia was associated with LV hypertrophy only in women. Higher BP, impaired fasting glucose, and triglycerides level were independently associated with LV diastolic dysfunction in women, whereas higher BP was the only independent predictor in men. The combination of increased BP, fasting glucose, and dyslipidemia was independently associated with LV diastolic dysfunction only in women.

CONCLUSIONS

Different MS factors are responsible for LV remodeling in women and men. The metabolic sequence of MS is more important for LV remodeling in women.

ANG II causes insulin resistance and induces cardiac metabolic switch and inefficiency: a critical role of PDK4

The renin-angiotensin system (RAS) may alter cardiac energy metabolism in heart failure. Angiotensin II (ANG II), the main effector of the RAS in heart failure, has emerged as an important regulator of cardiac hypertrophy and energy metabolism. We studied the metabolic perturbations and insulin response in an ANG II-induced hypertrophy model. Ex vivo heart perfusion showed that hearts from ANG II-treated mice had a lower response to insulin with significantly reduced rates of glucose oxidation in association with increased pyruvate dehydrogenase kinase 4 (PDK4) levels. Palmitate oxidation rates were significantly reduced in response to insulin in vehicle-treated hearts but remained unaltered in ANG II-treated hearts. Furthermore, phosphorylation of Akt was also less response to insulin in ANG II-treated wild-type (WT) mice, suggestive of insulin resistance. We evaluated the role of PDK4 in the ANG II-induced pathology and showed that deletion of PDK4 prevented ANG II-induced diastolic dysfunction and normalized glucose oxidation to basal levels. ANG II-induced reduction in the levels of the deacetylase, SIRT3, was associated with increased acetylation of pyruvate dehydrogenase (PDH) and a reduced PDH activity. In conclusion, our findings show that a combination of insulin resistance and decrease in PDH activity are involved in ANG II-induced reduction in glucose oxidation, resulting in cardiac inefficiency. ANG II reduces PDH activity via acetylation of PDH complex, as well as increased phosphorylation in response to increased PDK4 levels.

Cardiac dysfunction and oxidative stress in the metabolic syndrome: an update on antioxidant therapies

The metabolic syndrome (MetS) is a cluster of risk factors including obesity, insulin resistance, dyslipidemia, elevated blood pressure and glucose intolerance. The MetS increases the risk for cardiovascular disease (CVD) and type 2 diabetes. Each component of the MetS causes cardiac dysfunction and their combination carries additional risk. The mechanisms underlying cardiac dysfunction in the MetS are complex and might include lipid accumulation, increased fibrosis and stiffness, altered calcium homeostasis, abnormal autophagy, altered substrate utilization, mitochondrial dysfunction and increased oxidative stress. Mitochondrial and extra-mitochondrial sources of reactive oxygen species (ROS) and reduced antioxidant defense mechanisms characterize the myocardium of humans and animals with the MetS. The mechanisms for increased cardiac oxidative stress in the MetS are not fully understood but include increased fatty acid oxidation, mitochondrial dysfunction and enhanced NADPH oxidase activity. Therapies aimed to reduce oxidative stress and enhance antioxidant defense have been employed to reduce cardiac dysfunction in the MetS in animals. In contrast, large scale clinical trials using antioxidants therapies for the treatment of CVD have been disappointing because of the lack of efficacy and undesired side effects. The focus of this review is to summarize the current knowledge about the mechanisms underlying cardiac dysfunction in the MetS with a special interest in the role of oxidative stress. Finally, we will update the reader on the results obtained with natural antioxidant and mitochondria-targeted antioxidant therapies for the treatment of CVD in the MetS.

Central versus peripheral cardiovascular risk in metabolic syndrome

Individuals with metabolic syndrome (MetS; i.e., three of five of the following risk factors (RFs): elevated blood pressure, waist circumference, triglycerides, blood glucose, or reduced HDL) are thought to be prone to serious cardiovascular disease and there is debate as to whether the disease begins in the peripheral vasculature or centrally. This study investigates hemodynamics, cardiac function/morphology, and mechanical properties of the central (heart, carotid artery) or peripheral [total peripheral resistance (TPR), forearm vascular bed] vasculature in individuals without (1–2 RFs: n = 28), or with (≥3 RFs: n = 46) MetS. After adjustments for statin and blood pressure medication use, those with MetS had lower mitral valve E/A ratios (<3 RFs: 1.24 ± 0.07; ≥3 RFs: 1.01 ± 0.04; P = 0.025), and higher TPR index (<3 RFs: 48 ± 2 mmHg/L/min/m²; ≥3 RFs: 53 ± 2 mmHg/L/min/m²; P = 0.04). There were no differences in heart size, carotid artery measurements, cardiovagal baroreflex, pulse-wave velocity, stroke volume index, or cardiac output index due to MetS after adjustments for statin and blood pressure medication use. The use of statins was associated with increased inertia in the brachial vascular bed, increased HbA1c and decreased LDL cholesterol. The independent use of anti-hypertensive medication was associated with decreased predicted VO2max, triglycerides, diastolic blood pressure, interventricular septum thickness, calculated left ventricle mass, left ventricle posterior wall thickness, and left ventricle pre-ejection period, but increased carotid stiffness, HDL cholesterol, and heart rate. These data imply that both a central cardiac effect and a peripheral effect of vascular resistance are expressed in MetS. These data also indicate that variance in between-group responses due to pharmacological treatments are important factors to consider in studying cardiovascular changes in these individuals.

Plasma adiponectin concentration and its association with metabolic syndrome in patients with heart failure

PURPOSE

Plasma adiponectin concentrations are inversely related with metabolic syndrome (MetS), and MetS is associated with increased risk for heart failure (HF). However, the relationship between adiponectin and MetS in HF remains undetermined. Therefore, we tested whether MetS was associated with the degree of plasma adiponectin concentrations in HF patients.

MATERIALS AND METHODS

One hundred twenty eight ambulatory HF patients with left ventricular ejection fraction of <50% (80 males, 61.8 ± 11.9 years old) were enrolled for this cross-sectional study. Echocardiographic measurements were performed, and plasma concentrations of adiponectin, lipoproteins, apolipoproteins (apoB, apoA1) and high sensitive C-reactive protein (hsCRP) were measured.

RESULTS

Adiponectin concentrations in HF patients with MetS (n=43) were significantly lower than those without MetS (n=85) (9.7 ± 7.0 vs. 15.8 ± 10.9 μg/mL, p=0.001). Higher concentrations of apoB (p=0.017), apoB/A1 ratio (p<0.001), blood urea nitrogen (p=0.034), creatinine (p=0.003), and fasting insulin (p=0.004) were observed in HF patients with MetS compared with those without MetS. In HF patients with MetS, adiponectin concentrations were negatively correlated with hsCRP (r=-0.388, p=0.015) and positively correlated with the ratio of early mitral inflow velocity to early diastolic mitral annular velocity, E/E' (r=0.399, p=0.015). There was a significant trend towards decreased adiponectin concentrations with an increasing number of components of MetS (p for trend=0.012).

CONCLUSION

Our study demonstrated that adiponectin concentrations decreased in HF patients with MetS, and that relationship between adiponectin, inflammation and abnormal diastolic function, possibly leading to the progression of HF.