Early abnormalities of cardiac function in non-insulin-dependent diabetes mellitus and impaired glucose tolerance

Metformin inhibits cardiometabolic syndrome associated cognitive deficits in high fat diet rats

Objectives

Glucose intolerance and insulin resistance are hallmarks of metabolic syndrome and lead to Alzheimer's disease (AD). The purpose of this study is to elucidate the neuroprotective effect of metformin through insulin regulation with cardiometabolic and neurotransmitter metabolic enzyme regulation in high-fat, high-sucrose diet and streptozotocin (HFHS-STZ)-induced rats.

Methods

Male Wistar rats were treated with metformin (180 mg/kg and 360 mg/kg). STZ (35 mg/kg i.p.) injection was performed on the 14th day of 42 days of HFHS diet treatment. Brain neurotransmitter metabolic enzymes (acetylcholinesterase and monoamine oxidase) were determined along with sodium-potassium ATPase (Na+K+-ATPase). Plasma lipids and homeostasis model assessment of insulin resistance (HOMA-IR) was performed. Mean arterial blood pressure, heart rate and electrocardiogram (QT, QTc and RR intervals) were analysed with PowerLab.

Results

Metformin treatment significantly (p < 0.001) reduced the HOMA-IR index and decreased neurotransmitter metabolic enzymes such as AChE and MAO (p < 0.01 and p < 0.05). The lipid profile was significantly (p < 0.001) controlled with cardiometabolic functions.

Conclusions

Our investigation revealed that metformin has a remarkable role in regulating brain insulin, vascular system with monoaminergic metabolic enzymes and enhancing synaptic plasticity. Metformin may be a selective early therapeutic agent in metabolic syndrome associated with cognitive decline.

Multi-modality cardiac imaging in the management of diabetic heart disease

Diabetic heart disease is a major healthcare problem. Patients with diabetes show an excess of death from cardiovascular causes, twice as high as the general population and those with diabetes type 1 and longer duration of the disease present with more severe cardiovascular complications. Premature coronary artery disease and heart failure are leading causes of morbidity and reduced life expectancy. Multimodality cardiac imaging, including echocardiography, cardiac computed tomography, nuclear medicine, and cardiac magnetic resonance play crucial role in the diagnosis and management of different pathologies included in the definition of diabetic heart disease. In this review we summarise the utility of multi-modality cardiac imaging in characterising ischaemic and non-ischaemic causes of diabetic heart disease and give an overview of the current clinical practice. We also describe emerging imaging techniques enabling early detection of coronary artery inflammation and the non-invasive characterisation of the atherosclerotic plaque disease. Furthermore, we discuss the role of MRI-derived techniques in studying altered myocardial metabolism linking diabetes with the development of diabetic cardiomyopathy. Finally, we discuss recent data regarding the use of artificial intelligence applied to large imaging databases and how those efforts can be utilised in the future in screening of patients with diabetes for early signs of disease.

Determinants of Left Atrial Compliance in the Metabolic Syndrome: Insights from the "Linosa Study"

The association between left atrial (LA) impairment and cardiovascular diseases (CVD) and between dyslipidaemia and CVD are well known. The present study aims to investigate the relationships between metabolic factors and LA dimensions and compliance, as well as test the hypothesis that metabolic factors influence LA function independent from hemodynamic mechanisms. Arterial blood pressure (BP), waist and hip circumference, metabolic indices, and a complete echocardiographic assessment were obtained from 148 selected inhabitants (M/F 89/59; age 20−86 years) of Linosa Island, who had no history of CVD. At enrollment, 27.7% of the subjects met the criteria for metabolic syndrome (MetS) and 15.5% for arterial hypertension (HTN). LA compliance was reduced in subjects with MetS compared to those without (53 ± 27% vs. 71 ± 29%, p = 0.04) and was even lower (32 ± 17%, p = 0.01) in those with MetS and HTN. At multiple regression analysis, the presence of MetS independently determined LA maximal area (r = 0.56, p < 0.001), whereas systolic BP and the total cholesterol/HDL cholesterol ratio determined LA compliance (r = 0.41, p < 0.001). In an apparently healthy population with a high prevalence of MetS, dyslipidaemia seems to independently influence LA compliance. At a 5-year follow-up, LA compliance was reduced in both all-cause and CVD mortality groups, and markedly impaired in those who died of CVD. These findings may contribute to understanding the prognostic role of LA function in CVD and strengthen the need for early and accurate lipid control strategies.

The Diabetic Cardiomyopathy: The Contributing Pathophysiological Mechanisms

Individuals with diabetes mellitus (DM) disclose a higher incidence and a poorer prognosis of heart failure (HF) than non-diabetic people, even in the absence of other HF risk factors. The adverse impact of diabetes on HF likely reflects an underlying “diabetic cardiomyopathy” (DM–CMP), which may by exacerbated by left ventricular hypertrophy and coronary artery disease (CAD). The pathogenesis of DM-CMP has been a hot topic of research since its first description and is still under active investigation, as a complex interplay among multiple mechanisms may play a role at systemic, myocardial, and cellular/molecular levels. Among these, metabolic abnormalities such as lipotoxicity and glucotoxicity, mitochondrial damage and dysfunction, oxidative stress, abnormal calcium signaling, inflammation, epigenetic factors, and others. These disturbances predispose the diabetic heart to extracellular remodeling and hypertrophy, thus leading to left ventricular diastolic and systolic dysfunction. This Review aims to outline the major pathophysiological changes and the underlying mechanisms leading to myocardial remodeling and cardiac functional derangement in DM-CMP.

Echocardiography, an Indispensable Tool for the Management of Diabetics, with or without Coronary Artery Disease, in Clinical Practice

Diabetes mellitus is a major factor contributing to the development of cardiovascular disease. As morbidity and mortality rates rise dramatically, when target organ damage develops pre-symptomatic assessment is critical for the management of diabetic patients. Echocardiography is a noninvasive and reproducible method that may aid in risk stratification and in evaluation of treatment effects. The aim of this review is to analyze the echocardiographic techniques which can detect early alteration in cardiac function in patients with diabetes.

Factors Associated with the Remission of Type 1 Diastolic Dysfunction after Dapagliflozin Treatment in Patients with Type 2 Diabetes

Patients with type 2 diabetes (T2DM) are at high risk of developing cardiovascular disease and heart failure (HF), both with preserved and reduced ejection fraction of the left ventricle. Previous research demonstrated that dapagliflozin treatment is associated with the remission of type 1 diastolic dysfunction (DD1) in patients with T2DM. The main aim of this study was to evaluate the possible baseline predictors associated with the remission of DD1 in patients with T2D after one year of dapagliflozin treatment. In this prospective and observational study, 45 patients with T2DM were evaluated before and after one year of treatment with 10 mg dapagliflozin daily added to their background therapy. In the studied group, 73.3% (33/45) of the patients had DD1 at baseline. The primary outcome of this research was DD1 remission. DD1 remission was associated with improvement of liver stiffness, an increase in estimated glomerular filtration rate (eGFR), and a decrease in hemoglobin A1c (HbA1c). Independent predictors for the remission of DD1 were a more than 0.4 kPa difference in the initial stiffness score and the 1-year assessment fibrosis score and a duration of diabetes ≤8 years. Age, body mass index (BMI), or patient weight after one year did not influence the DD1 outcome. Patients with a T2DM duration of less than eight years have the additional benefit of DD1 remission associated with dapagliflozin treatment beyond the conventional benefits such as improvements in glycemic control, cardiovascular, renal, and hepatic risk reductions. In patients with T2DM, the remission of DD1 was associated with decrease of liver stiffness.

A rat model of enhanced glycation mimics cardiac phenotypic components of human type 2 diabetes : A translational study using MRI

BACKGROUND

The success of translational research depends on how well animal models mimic the pathophysiology of the human phenotype, and on the identification of disease mechanisms such as enhanced glycation.

METHODS

Here, we studied cardiac MRI and metabolic phenotypes in human type 2 diabetes (N = 106; 55 patients+51 controls) and animal models with distinct levels of fat diet and end glycation products, to model the role of these factors in the cardiac phenotype. We included four groups of rats, designed to evaluate the role of lipid load and glucotoxicity in cardiac function and to correlate these with the cardiac phenotype observed in humans. We also aimed to assess into which extent phenotypes were related to specific risk factors.

RESULTS

Stroke Volume (SV) and Peak Filling Rate (PFR) measures were similarly discriminative both in humans and animal models, particularly when enhanced glycation was present. Factorial analysis showed that reduction of multidimensionality into common main explanatory factors, in humans and animals, revealed components that equally explained the variance of cardiac phenotypes (87.62% and 83.75%, respectively). One of the components included, both in humans and animals, SV, PFR and peak ejection rate (PER). The other components included in both humans and animals are the following: ESV (end systolic volume), left ventricular mass (LVM) and ejection fraction (EF). These components were useful for between group discrimination.

CONCLUSIONS

We conclude that animal models of enhanced glycation and human type 2 diabetes share a striking similarity of cardiac phenotypic components and relation with metabolic changes, independently of fact content in the diet, which reinforces the role of glucose dysmetabolism in left ventricular dysfunction and provides a potentially useful approach for translational research in diabetes, in particular when testing new therapies early on during the natural history of this condition.

Left ventricular diastolic dysfunction in diabetes mellitus and the therapeutic role of exercise training

Abstract Left ventricular diastolic dysfunction (LVDD) with normal ejection fraction is considered common among people with diabetes mellitus (DM). LVDD is a progressive condition and an independent predictor of mortality in diabetic patients. The etiopathogenesis of LVDD is multifactorial, including diabetes associated comorbidities, such as hypertension, coronary atherosclerosis and obesity, as well as myocardial vascular and metabolic disturbances which lead to diabetic cardiomyopathy. Early stages of LVDD may be detected using echocardiographic techniques. Treatment strategies evolve, based on a better understanding of pathogenic mechanisms, although it is still difficult to efficiently control LVDD evolution. This review synthesizes the main pathophysiological processes and clinical features that characterize DM associated LVDD. Among treatment options, the therapeutic relevance of exercise training programs is underlined. Key words: diabetes mellitus, left ventricular diastolic dysfunction, physical training,

Dynamics of Epicardiac Fat and Heart Function in Type 2 Diabetic Patients Initiated with SGLT-2 Inhibitors

PURPOSE

The aim of this study was to assess the dynamics of epicardiac adipose tissue (EAT) thickness and total volume as well as that of systolic and diastolic dysfunction in a group of patients with type 2 diabetes (T2D) after initiation of sodium glucose co-transporter 2 (SGLT 2) inhibitors therapy.

PATIENTS AND METHODS

This prospective, observational study included 53 patients with T2D who received SGLT-2 inhibitors for 24 weeks. In all patients, echocardiographic screening for EAT, systolic and diastolic dysfunction and non-contrast computed tomography scans were performed, both before and after 24 weeks of SGLT-2 inhibition. Imagistic evaluation was followed by the association's analysis between the dynamics of EAT and heart function, as well as the patient's clinical and biological parameters. We considered a decrease or increase of more than 10% in EAT as being clinically significant.

RESULTS

The mean volume of EAT decreased significantly after SGLT 2 inhibition (37.8±17.2 vs. 20.7±7 cm³; p<0.001). Median values of EAT thickness also decreased significantly (5.95 vs. 3.01 mm; p<0.001). Most patients, 75.4% (40/53), presented more than 10% decrease in EAT volume, 9.5% (5/53) had stable EAT volume values, while in 15.1% (8/53) the means of EAT volume increased. 73.5% of the patients had diastolic dysfunction type 1 (DD 1) at baseline. No significant change was observed in the left ventricular ejection fraction or diastolic dysfunction after 24 weeks of treatment. Although not statistically significant, an improvement in cardiac function has been noticed throughout the duration of 1 year of treatment with SGLT 2 inhibitors.

CONCLUSION

This study showed the beneficial effect of SGLT 2 inhibitors on EAT after a short period of treatment, but there were no significant changes in the systolic function during the 1st year of study. However, reducing epicardial fat has led to remission of diastolic dysfunction.

Right ventricular dysfunction and remodeling in diabetic cardiomyopathy

The increasing prevalence of diabetic cardiomyopathy (DCM) is an important threat to health worldwide. While left ventricular (LV) dysfunction in DCM is well recognized, the accurate detection, diagnosis, and treatment of changes in right ventricular (RV) structure and function have not been well characterized. The pathophysiology of RV dysfunction in DCM may share features with LV diastolic and systolic dysfunction, including pathways related to insulin resistance and oxidant injury, although the RV has a unique cellular origin and composition and unique biomechanical properties and is coupled to the lower-impedance pulmonary vascular bed. In this review, we discuss potential mechanisms responsible for RV dysfunction in DCM and review the imaging approaches useful for early detection, protection, and intervention strategies. Additional data are required from animal models and clinical trials to better identify the onset and features of altered RV and pulmonary vascular structure and function during the onset and progression of DCM and to determine the efficacy of early detection and treatment of RV dysfunction on clinical symptoms and outcomes.

Cardiovascular sexual dimorphism in a diet-induced type 2 diabetes rodent model, the Nile rat (Arvicanthis niloticus)

Background

The Nile rat (Arvicanthis niloticus) is an emerging laboratory model of type 2 diabetes. When fed standard rodent chow, the majority of males progress from hyperinsulinemia by 2 months to hyperglycemia by 6 months, while most females remain at the hyperinsulinemia-only stage (prediabetic) from 2 months onward. Since diabetic cardiomyopathy is the major cause of type-2 diabetes mellitus (T2DM)-related mortality, we examined whether sexual dimorphism might entail cardiac functional changes. Our ultimate goal was to isolate the effect of diet as a modifiable lifestyle factor.

Materials and methods

Nile rats were fed either standard rodent chow (Chow group) or a high-fiber diet previously established to prevent type 2 diabetes (Fiber group). Cardiac function was determined with echocardiography at 12 months of age. To isolate the effect of diet alone, only the small subset of animals resistant to both hyperinsulinemia and hyperglycemia were included in this study.

Results

In males, Chow (compared to Fiber) was associated with elevated heart rate and mitral E/A velocity ratio, and with lower e’-wave velocity, isovolumetric relaxation time, and ejection time. Of note, these clinically atypical types of diastolic dysfunction occurred independently of body weight. In contrast, females did not exhibit changes in cardiovascular function between diets.

Conclusions

The higher prevalence of T2DM in males correlates with their susceptibility to develop subtle diastolic cardiac dysfunction when fed a Western style diet (throughout most of their lifespan) despite no systemic evidence of metabolic syndrome, let alone T2DM.

Echocardiographic feature of diabetic cardiomyopathy: where are we now?

We are now entering the very exciting era of treatment and management of diabetes mellitus (DM) with the emergence of new therapeutic agents, including sodium-glucose cotransporter 2 inhibitors (SGLT2i) and dipeptidyl peptidase-4 inhibitor (DPP-4i). From a cardiology and echocardiography perspective, the existence of diabetic cardiomyopathy has been proven through over four decades of discussion. DM is highly prevalent in patients with heart failure (HF). Independent associations are found after adjusting for hypertension (HTN) and coronary artery disease (CAD). In patients with both DM and HF, the prognosis is extremely dismal. In this review, the main focus is on both diabetic cardiomyopathy per se and its typical features (including myocardial additive insult related to DM), diagnosis, and management.

Assessment of arterio-ventricular coupling by tissue Doppler and wave intensity in type 2 diabetes

Aim

To evaluate ventricular-arterial coupling in preclinical cardiovascular disease, we used a new wave intensity approach and tissue Doppler in patients with and without type 2 diabetes mellitus (DM).

Methods

Sixty-five type 2 diabetes patients and 57 control individuals with normal systolic left ventricular function and without overt coronary or peripheral artery disease were assessed by tissue Doppler for myocardial velocities and by a combined Doppler and echo-tracking system (Aloka SSD-5500, Tokyo) for local arterial stiffness (epsilon, pulse wave velocity) and the characteristic peaks W1 and W2 of pulse wave intensity.

Results

Diabetes patients had significantly higher systolic blood pressure and pressure derivates (p<0.002). Diastolic myocardial velocity (Ve) was decreased (p<0.001). Epsilon and pulse wave velocity (p<0.001) were higher and so was W1 (11785±7491 vs. 9191±4299, p<0.04) but not W2. In the pooled data, independent predictors for Ve were age, septal wall thickness, Vs and HbA1C (R2 duration of diabetes (R2 0.479). 0.426) and for W1 systolic blood pressure, Vs, W2 and duration of diabetes (R2 0.479).

Conclusion

In type 2 diabetes pump function is preserved and maintained against increased arterial stiffness and impedance at the expense of increased myocardial oxygen requirements. Tissue Doppler and wave intensity measurements may be useful for therapeutic monitoring.

Diabetic Cardiomyopathy: A Forensic Perspective

Diabetes mellitus is a common condition affecting both adults and children. Long-standing diabetes is associated with cardiovascular abnormalities such as coronary artery atherosclerosis, microvascular changes, hypertension, kidney disease, and heart failure. Its association with heart failure in the absence of coronary artery disease and hypertension was termed diabetic cardiomyopathy in the 1970s and is believed to account for some of the cardiac mortality in diabetic patients. This entity may be implicated as the cause of sudden cardiac death in the small percentage of diabetic patients in which the autopsy fails to demonstrate evidence of nonketotic hyperosmolar coma, diabetic ketoacidosis, or atherosclerotic and hypertensive cardiovascular disease. Molecular and metabolic alterations have been studied to explain the pathophysiology of this disease.

Impaired fasting glucose and left ventricular diastolic dysfunction in middle-age adults: a retrospective cross-sectional analysis of 2971 subjects

BACKGROUND

Left ventricular (LV) diastolic dysfunction (LVDD) is a well-established and early echocardiographic characteristic of diabetic cardiomyopathy. However, there are limited data on the association between impaired fasting glucose (IFG) and LVDD.

OBJECTIVE

To determine whether IFG is associated with LVDD among middle age adults.

METHODS

Amongst 3781 subjects screened in an annual health survey program and referred for an echocardiogram, 2971 individuals without LV systolic dysfunction or valvular heart disease were selected. Mean age of study population was 59 ± 12 years and 75% were men. The subjects were categorized into three groups: euglycemia (N = 2025), IFG (N = 534) and diabetes mellitus (DM; N = 412). Doppler echocardiography readers were blinded to glycemic state. Subjects with impaired LV relaxation, pseudo-normal or restrictive filling patterns were defined as having LVDD.

RESULTS

LVDD was diagnosed in 574 (19 %) of subjects and it was more prevalent among patients with IFG and DM than in euglycemic individuals (27, 30 and 15%, respectively; p < 0.001). Patients with IFG and DM had lower ratios of early (E) to late (A) trans-mitral flow (0.9 ± 0.3 and 0.9 ± 0.3 vs. 1.1 ± 0.4, respectively, p < 0.001). LV hypertrophy (LVH) was also more prevalent among patients with IFG and DM (11 and 18%, respectively, vs. 9%; p < 0.001). Multivariate binary logistic regression model adjusted to age, gender, obesity, LVH, renal function, total, high and low density lipoprotein cholesterol, triglycerides, ischemic heart disease, hypertension and LV ejection fraction showed that patients with IFG were 43% more likely to have LVDD compared with euglycemic subjects (95% confidence interval 1.12-1.83, p = 0.004).

CONCLUSIONS

IFG is independently associated with a significant increase in the likelihood for the presence of LVDD in middle aged adults.

Study on Diastolic Dysfunction in Newly Diagnosed Type 2 Diabetes Mellitus and its Correlation with Glycosylated Haemoglobin (HbA1C)

INTRODUCTION

Left ventricular diastolic dysfunction (LVDD) represents the first stage of diabetic cardiomyopathy preceding changes in systolic function, reinforcing the importance of early examination of ventricular function in individuals with diabetes mellitus (DM). This cross-sectional study was conducted to determine the incidence of asymptomatic LVDD in newly diagnosed normotensive cases of type 2 diabetes subjects, and its relation to glycosylated haemoglobin (HbA1C), age at the time of diagnosis, body mass index (BMI) and serum total cholesterol.

AIM AND OBJECTIVE

To study the incidence of left ventricular diastolic dysfunction (LVDD) and its correlation with HbA1C in normotensive, newly diagnosed type 2 diabetic patients.

MATERIALS AND METHODS

This cross-sectional study was done in western U.P. on 100 patients of newly diagnosed (within 1 month) type 2 DM between patients 30 and 60 years of age, visiting the Medicine and Endocrinology outpatient Department of LLRM Medical College, Meerut. Patients with established type 2 diabetes and already taking antidiabetic treatment, cardiac diseases like valvular heart disease, ischemic and hypertensive heart disease, congestive heart failure, cardiomyopathy, renal failure, chronic pulmonary disease, severe anaemia and haemoglobinopathies were excluded from the study. These patients were informed about the study and informed consent was obtained before proceeding with the investigations. Patients selected were evaluated with relevant investigations like fasting and post prandial blood sugar, HbA1C level, lipid profile and 2D echocardiography to assess LVDD. These selected patients were divided in 2 groups; one with left ventricular diastolic dysfunction (LVDD) and second group of subjects without LVDD. Various parameters like HbA1C, age, body mass index and serum cholesterol were evaluated between these 2 groups. Statistical analysis was performed using Student t-test, Chi-square and Fisher Exact-test.

RESULTS

Out of 100 patients 65 were males and 35 females. Mean age of the population was 50.08 ± 6.32 years. Overall incidence of LVDD was 41%. Grade 1 LVDD was most common. Mean HbA1C level of LVDD group was found higher as compared to those without LVDD.

CONCLUSION

LVDD is very common at the time of diagnosis of type 2 DM even in normotensive patients independent of confounding effect of hypertension, ischemia and BMI. HbA1C and age, were found to be strong indicators of LVDD in newly diagnosed cases of Type 2 DM.

Association of micro albuminuria with diastolic function in obese normotensive no diabetic individuals

Background:

Recently, an association between impaired diastolic function and increased urinary albumin excretion has been hypothesized.

Objectives:

We tried to assess the association between diastolic function and micro albuminuria in normotensive no diabetic obese individuals.

Patients and Methods:

This cross-sectional study was conducted on 186 consecutive obese normotensive no diabetic individuals who were older than 18 years and attended the outpatient health clinic at the Tehran Municipality in 2011. Systolic and diastolic blood pressures were measured using a standard mercury sphygmomanometer. Micro albuminuria was defined as abnormal urinary albumin to creatinine ratio (UACR) between 30 and 300 mg/g/d.

Results:

An adverse significant linear correlations was found between the UACR measurement and diastolic function (r = -0.184 and P = 0.012); however, this correlation was insignificant for systolic function (r = 0.007 and P = 0.926). Multivariable linear regression analysis showed that UACR index had a significant reverse correlation with diastolic function (Standardized Beta = -0.218 and P = 0.006).

Conclusions:

Our study obtained some evidences on the association of micro albuminuria with diastolic dysfunction in obese normotensive no diabetic individuals. Nonetheless, more assessment is necessary for obtaining a causal relationship between micro albuminuria and diastolic dysfunction.

The relationship between epicardial fat thickness and gestational diabetes mellitus

AIM

Gestational diabetes mellitus (GDM) is associated with cardiovascular diseases; however, the relationship between epicardial fat thickness (EFT) and GDM remains unclear. The present study evaluates and compares EFT using transthoracic echocardiography in pregnant women with GDM.

MATERIALS AND METHODS

This cross-sectional study included 129 pregnant women in the third trimester: 65 with GDM (GDM group) and 64 with uncomplicated pregnancies (control group). As defined by the World Health Organization, the diagnosis of GDM was based on an abnormal 2-h oral glucose tolerance test (OGTT) results. We used echocardiography to measure EFT in blood samples for all the participants.

RESULTS

The postprandial blood glucose level was significantly higher in the GDM group than in the control group (P < 0.001). There were no significant differences in BMI, heart rate, systolic and diastolic blood pressure or lipid parameters between the groups. In the GDM group, isovolumic relaxation time (IVRT) parameters were significantly higher than in the control group. EFT was significantly higher in the GDM group (P < 0.001) and was correlated with postprandial glucose, BMI, age, and heart rate in both the groups. Only postprandial glucose and BMI remained significantly associated with EFT after multiple stepwise regression analysis.

CONCLUSION

Echocardiographically measured EFT was significantly higher in the patients with GDM. The findings show that EFT was strongly correlated with postprandial glucose.

Mechanisms underlying the impaired contractility of diabetic cardiomyopathy

Cardiac dysfunction is a well-known consequence of diabetes, with sustained hyperglycaemia leading to the development of a cardiomyopathy that is independent of cardiovascular disease or hypertension. Animal models of diabetes are commonly used to study the pathophysiology of diabetic cardiomyopathy, with the hope that increased knowledge will lead ultimately to better therapeutic strategies being developed. At physiological temperature, left ventricular trabeculae isolated from the streptozotocin rat model of type 1 diabetes showed decreased stress and prolonged relaxation, but with no evidence that decreased contractility was a result of altered myocardial Ca²⁺ handling. Although sarcoplasmic reticulum (SR) Ca²⁺ reuptake appeared slower in diabetic trabeculae, it was offset by an increase in action-potential duration, thereby maintaining SR Ca²⁺ content and favouring increased contraction force. Frequency analysis of t-tubule distribution by confocal imaging of ventricular tissue labeled with wheat germ agglutinin or ryanodine receptor antibodies showed a reduced T-power for diabetic tissue, but the differences were minor in comparison to other models of heart failure. The contractile dysfunction appeared to be the result of disrupted F-actin in conjunction with the increased type I collagen, with decreased myofilament Ca²⁺ sensitivity contributing to the slowed relaxation.

Left ventricular diastolic function in type 2 diabetes mellitus and the association with coronary artery calcium score: a cardiac MRI study

OBJECTIVE

The purpose of this study was to compare cardiac MRI-derived parameters of left ventricular (LV) diastolic function between uncomplicated type 2 diabetes mellitus (DM2) and normoglycemic control subjects and to evaluate whether these parameters of LV diastolic function are related to coronary atherosclerosis.

SUBJECTS AND METHODS

We prospectively studied 41 subjects with DM2 and 21 normoglycemic control subjects (30 women and 32 men; mean age, 57.2 ± 7.1 [SD] years) with no evidence of overt cardiovascular disease. We used cardiac MRI to measure LV volumes, LV peak filling rate (PFR), and transmitral flow and CT to determine coronary artery calcium scores.

RESULTS

Absolute values of the peak filling rate (PFR) were significantly lower in DM2 patients than in control subjects (mean ± SD, 293.2 ± 51.7 vs 375.7 ± 102.8 mL/s, respectively; p < 0.001). Mitral peak E velocities (mean ± SD, 42.8 ± 10.7 vs 48.8 ± 10.4 cm/s; p = 0.040) and peak E velocity-to-peak A velocity ratios (0.88 ± 0.3 vs 1.1 ± 0.3; p = 0.002) were also lower in DM2 patients compared with control subjects. DM2 patients with coronary artery calcification showed a lower PFR normalized to stroke volume (SV) (mean ± SD, 4.4 ± 1.0 vs 5.3 ± 1.4, respectively; p = 0.038) and lower mitral peak E velocities (40.1 ± 11.3 vs 48.0 ± 7.3 cm/s; p = 0.024) than DM2 patients without coronary calcification. PFR normalized to SV was independently associated with the presence of coronary artery calcification (β = -1.5, p = 0.005).

CONCLUSION

DM2 decreases cardiovascular MRI-derived parameters of LV diastolic function. Patients with DM2 and coronary atherosclerosis show a more impaired LV diastolic function than patients without coronary atherosclerosis.

Hyperglycemia has a greater impact on left ventricle function in South Asians than in Europeans

OBJECTIVE Diabetes is associated with left ventricular (LV) diastolic and systolic dysfunction. South Asians may be at particular risk of developing LV dysfunction owing to a high prevalence of diabetes. We investigated the role of diabetes and hyperglycemia in LV dysfunction in a community-based cohort of older South Asians and white Europeans. RESEARCH DESIGN AND METHODS Conventional and Doppler echocardiography was performed in 999 participants (542 Europeans and 457 South Asians aged 58-86 years) in a population-based study. Anthropometry, fasting bloods, coronary artery calcification scoring, blood pressure, and renal function were measured. RESULTS Diabetes and hyperglycemia across the spectrum of HbA1c had a greater adverse effect on LV function in South Asians than Europeans (N-terminal-probrain natriuretic peptide β ± SE 0.09 ± 0.04, P = 0.01, vs. -0.04 ± 0.05, P = 0.4, P for HbA1c/ethnicity interaction 0.02), diastolic function (E/e' 0.69 ± 0.12, P < 0.0001, vs. 0.09 ± 0.2, P = 0.6, P for interaction 0.005), and systolic function (s' -0.11 ± 0.06, P = 0.04, vs. 0.14 ± 0.09, P = 0.1, P for interaction 0.2). Multivariable adjustment for hypertension, microvascular disease, LV mass, coronary disease, and dyslipidemia only partially accounted for the ethnic differences. Adverse LV function in diabetic South Asians could not be accounted for by poorer glycemic control or longer diabetes duration. CONCLUSIONS Diabetes and hyperglycemia have a greater adverse effect on LV function in South Asians than Europeans, incompletely explained by adverse risk factors. South Asians may require earlier and more aggressive treatment of their cardiometabolic risk factors to reduce risks of LV dysfunction.

Cardiovascular characteristics in subjects with increasing levels of abnormal glucose regulation: the Strong Heart Study

OBJECTIVE

To evaluate whether impaired fasting glucose (IFG) or the combination of IFG and impaired glucose tolerance (IGT) is associated with progressive abnormalities of cardiac geometry and function.

RESEARCH DESIGN AND METHODS

We studied 562 nondiabetic (311 women), nonhypertensive participants of the second Strong Heart Study exam, without prevalent cardiovascular (CV) disease and with estimated glomerular filtration rate ≥60 mL/min/1.73 m(2) (age 46-65 years, 198 with isolated IFG [35%], and 132 with combined IFG and IGT [23%]). Anthropometric parameters, insulin resistance, fibrinogen, C-reactive protein (CRP), lipid profile, blood pressure (BP), and echocardiographic parameters were compared with 232 participants with normal glucose tolerance (NGT).

RESULTS

BMI, prevalence of central obesity, homeostatic model assessment index of insulin resistance, plasma triglycerides, fibrinogen, and CRP increased progressively across categories of glucose intolerance (P < 0.0001), with the IFG+IGT group having higher values than those with isolated IFG (0.05 < P < 0.0001). Compared with NGT, both IFG and IFG+IGT exhibited greater left ventricular (LV) mass (P < 0.0001) and lower Doppler early peak rapid filling velocity to peak atrial filling velocity ratio (P < 0.005), without differences in LV systolic function. The odds of LV hypertrophy (LV mass index >46.7 in women or >49.2 g/m(2.7) in men) was 3.5 in IFG participants (95% CI 0.68-17.76; P = NS) and 9.76 (2.03-46.79; P = 0.004) in IFG+IGT, compared with NGT, after adjustment for age, sex, heart rate, systolic BP, and waist circumference (WC). In the overall sample, LV mass index was associated with WC (P = 0.033), CRP (P = 0.027), and 2-h oral glucose tolerance test (P = 0.001) independently of confounders.

CONCLUSIONS

Cardiometabolic profile and markers of inflammation are more severely altered in men and women with both IFG and IGT compared with those with IFG alone. These individuals, in the absence of hypertension, have a 10-fold greater probability of preclinical CV disease (LV hypertrophy).

Diabetic cardiovascular disease: getting to the heart of the matter

Diabetes is a major risk factor for heart disease, and heart disease is responsible for substantial morbidity and mortality among people living with diabetes. The diabetic metabolic milieu predisposes to aggressive obstructive coronary artery disease that causes heart attacks, heart failure, and death. Furthermore, diabetes can be associated with heart failure, independent of underlying coronary artery disease, hypertension, or valve abnormalities. The pathogenesis of the vascular and myocardial complications of diabetes is, as yet, incompletely understood. Although a number of medical and surgical approaches can improve outcomes in diabetic patients with cardiovascular disease, much remains to be learned in order to optimize approaches to these critical complications.

Effects of perindopril-indapamide on left ventricular diastolic function and mass in patients with type 2 diabetes: the ADVANCE Echocardiography Substudy

BACKGROUND

The Action in Diabetes and Vascular Disease (ADVANCE) Study demonstrated that a fixed combination of perindopril and indapamide reduced the risk of major vascular events and mortality in patients with type 2 diabetes. This Echocardiographic Substudy was designed to determine the effects of this treatment on left ventricular diastolic function and left ventricular mass.

METHODS

Five hundred and fifty-five patients entering ADVANCE underwent quantitative echocardiography prior to randomization and after 6 months and 4 years of treatment with perindopril-indapamide or placebo. Main end points were left ventricular diastolic function (ratio of mitral E velocity/early medial mitral annular tissue Doppler velocity, E/Em, and left atrial volume index) and left ventricular mass index.

RESULTS

Overall, blood pressure was reduced in the perindopril-indapamide group compared with placebo. E/Em and left atrial volume index both increased over the 4 years. There was no effect of perindopril-indapamide on E/Em, although there was a small attenuation of the increase in left atrial volume index with active treatment. Left ventricular mass index was reduced by 2.7 g/m with active treatment (95% confidence interval -5.0 to -0.1, P = 0.04).

CONCLUSION

Compared with placebo, the perindopril-indapamide combination reduced blood pressure and left ventricular mass in patients with diabetes, but did not improve left ventricular diastolic function. Left ventricular diastolic function worsened in both groups over 4 years, despite blood pressure reduction and reduction in left ventricular mass. Improving left ventricular diastolic function remains a challenge in patients with diabetes.

Comparison of quantity of left ventricular scarring and remodeling by magnetic resonance imaging in patients with versus without diabetes mellitus and with coronary artery disease

Diabetic patients with coronary artery disease (CAD) are more likely to develop heart failure (HF) than nondiabetic patients, but the mechanism responsible is unclear. Evidence suggests that infarct size and accompanying remodeling may not explain this difference. We used cardiac magnetic resonance (CMR) imaging to compare degree of left ventricular (LV) myocardial scar and remodeling in diabetic and nondiabetic patients with CAD. We evaluated 85 patients (39 diabetic, 46 nondiabetic) who underwent coronary angiography showing obstructive CAD and CMR imaging within 6 months of each other. Myocardial scar was measured by late gadolinium enhancement on CMR imaging and was graded according to spatial and transmural extents on a semiquantitative scale. More diabetic than nondiabetic patients had HF (69% vs 43%, p <0.03); however, groups did not differ in total scar burden (0.94 ± 0.60 vs 1.17 ± 0.74, p = NS), spatial extent of scar, or extent of transmural scar. Diabetes remained an independent predictor of HF after adjustment for CAD and other variables. LV ejection fraction (36 ± 12% vs 37 ± 14%, p = NS) and end-diastolic volume (215 ± 56 vs 217 ± 76 ml, p = NS) were similar for diabetic and nondiabetic patients, respectively. In conclusion, although diabetic patients with CAD had a higher prevalence of HF than nondiabetic patients, there was no difference in myocardial scar, LV volume, or LV ejection fraction. These findings support the theory that mechanisms other than extent of myocardial injury and negative remodeling play a significant role in the development of HF in diabetic patients with CAD.

Systemic hemodynamics in relation to glucose tolerance: the Health 2000 Survey

The influence of impaired glucose metabolism--that is, impaired fasting glucose, impaired glucose tolerance (IGT), and type 2 diabetes mellitus diabetes (DM2)--on systemic hemodynamics is largely unknown. Therefore, we investigated the associations of glucose metabolism disturbances with stroke index (SI), cardiac index, systemic vascular resistance index (SVRI), arterial pulse wave velocity (PWV), and heart rate among Finnish adults (N = 389; mean age, 58.3 ± 7.9 years) participating in the Health 2000 Survey. Systemic hemodynamic parameters were measured using the whole-body impedance cardiography device, and an oral glucose tolerance test (OGTT) was performed to evaluate glucose tolerance status. We found a decreasing trend for SI and increasing trends for SVRI and PWV according to the worsening of glucose tolerance (P for trend < .003 for all). In pairwise comparisons, SI was lower in the impaired fasting glucose group (P = .041) and the IGT group (P < .001) as compared with the normal glucose tolerance (NGT) group. Systemic vascular resistance index was higher in the IGT group (P = .045) and the DM2 group (P = .043) than in the NGT group. Subjects with IGT or DM2 had higher arterial PWV (10.7 ± 0.2 m/s, P < .001 and 11.7 ± 0.5 m/s, P = .001, respectively) than subjects with NGT (9.5 ± 0.1 m/s). Moreover, 2-hour glucose in OGTT was an independent determinant of SVRI and PWV (P < .001 and P = .005, respectively) in multivariable linear regression models. In conclusion, the present study demonstrates that glucose intolerance, even without DM2, associates with several adverse changes in systemic hemodynamics and that 2-hour glucose in OGTT is an independent determinant of SVRI and PWV. These findings support the systematic evaluation of glucose tolerance status in the estimation of cardiovascular risk among the middle-aged population.

Atrial substrate properties and outcome of catheter ablation in patients with paroxysmal atrial fibrillation associated with diabetes mellitus or impaired fasting glucose

Diabetes mellitus has been reported to be an independent risk factor of atrial fibrillation (AF). The present study investigated the atrial substrate properties and clinical outcome of catheter ablation in patients with paroxysmal AF and abnormal glucose metabolism. A total of 228 patients with paroxysmal AF who had undergone catheter ablation for the first time were enrolled. An abnormal glucose metabolism (n = 65) was defined as diabetes mellitus or an impaired fasting glucose. We analyzed the clinical and electrophysiologic characteristics in, and the clinical outcome of, patients with AF with and without an abnormal glucose metabolism. The right atrial (107.2 ± 15.4 vs 96.0 ± 16.5 ms, p < 0.001) and left atrial (108.4 ± 22.3 vs 94.0 ± 17.5 ms, p < 0.001) total activation times were significantly longer in the patients with AF and an abnormal glucose metabolism than in those without an abnormal metabolism. Furthermore, the right atrial (1.46 ± 0.61 vs 2.00 ± 0.70 mV, p < 0.001) and left atrial (1.48 ± 0.74 vs 2.05 ± 0.78 mV, p < 0.001) bipolar voltages were significantly lower in those with AF and an abnormal glucose metabolism than in those without. The AF recurrence rate was also greater in the patients with an abnormal glucose metabolism (18.5% vs 8.0%, p = 0.022) than in those without. The follow-up duration was 18.8 ± 6.4 months. In conclusion, an abnormal glucose metabolism affects the biatrial substrate properties with an intra-atrial conduction delay, decreased voltage, and greater recurrence rate after catheter ablation.

Diastolic dysfunction in diabetes and the metabolic syndrome: promising potential for diagnosis and prognosis

Cardiac disease in diabetes mellitus and in the metabolic syndrome consists of both vascular and myocardial abnormalities. The latter are characterised predominantly by diastolic dysfunction, which has been difficult to evaluate in spite of its prevalence. While traditional Doppler echocardiographic parameters enable only semiquantitative assessment of diastolic function and cannot reliably distinguish perturbations in loading conditions from altered diastolic functions, new technologies enable detailed quantification of global and regional diastolic function. The most readily available technique for the quantification of subclinical diastolic dysfunction is tissue Doppler imaging, which has been integrated into routine contemporary clinical practice, whereas cine magnetic resonance imaging (CMR) remains a promising complementary research tool for investigating the molecular mechanisms of the disease. Diastolic function is reported to vary linearly with age in normal persons, decreasing by 0.16 cm/s each year. Diastolic function in diabetes and the metabolic syndrome is determined by cardiovascular risk factors that alter myocardial stiffness and myocardial energy availability/bioenergetics. The latter is corroborated by the improvement in diastolic function with improvement in metabolic control of diabetes by specific medical therapy or lifestyle modification. Accordingly, diastolic dysfunction reflects the structural and metabolic milieu in the myocardium, and may allow targeted therapeutic interventions to modulate cardiac metabolism to prevent heart failure in insulin resistance and diabetes.

Effect of reduced total blood volume on left ventricular volumes and kinetics in type 2 diabetes

AIM

Although impaired left ventricular (LV) diastolic function is commonly observed in patients with type 2 diabetes, it remains unclear whether the impairment is caused by altered LV relaxation or changes in LV preload. The purpose of this study was to examine the influence of LV function and LV loading conditions on stroke volume in men with type 2 diabetes.

METHODS

Cardiac magnetic resonance imaging scans were performed in eight men with type 2 diabetes and 11 non-diabetic men matched for age, weight and physical activity level. Total blood volume was determined with the Evans blue dye dilution technique.

RESULTS

End-diastolic volume (EDV), the ratio of peak early to late mitral inflow velocity (E/A) and stroke volume were lower in men with type 2 diabetes than in non-diabetic individuals. Peak filling rate and peak ejection rate were not different between diabetic and non-diabetic individuals; however, men with type 2 diabetes had proportionally longer systolic duration than non-diabetic individuals. Heart rate was higher and total blood volume was lower in men with type 2 diabetes. The lower total blood volume was correlated with a lower EDV in men with type 2 diabetes.

CONCLUSIONS

Men with type 2 diabetes have an altered cardiac cycle and lower end-diastolic and stroke volume. A lower total blood volume and higher heart rate in men with type 2 diabetes suggest that changes in LV preload, independent of changes in LV relaxation or contractility, influence LV diastolic filling and stroke volume in this population.

Effect of diabetes and hypertension on left ventricular diastolic function in a high-risk population without evidence of heart disease

AIMS

To assess the independent and combined effects of diabetes and hypertension on left ventricular (LV) diastolic function in a community-based cohort at high cardiovascular risk.

METHODS AND RESULTS

Two-dimensional echocardiography was performed in 708 subjects from the Cardiac Abnormalities and Brain Lesions (CABL) study. Peak diastolic early (E) and late (A) transmitral flow, and tissue Doppler-derived early mitral annulus velocity (E') were recorded, and E/A and E/E' ratios were calculated. The population was divided into four groups: those without hypertension or diabetes (HT-/DM-), those with only hypertension (HT), only diabetes (DM), and with hypertension plus diabetes (HT + DM). In multivariate analysis, hypertension and diabetes were independent predictors of worse diastolic function. The coexistence of hypertension and diabetes was associated with greater impairment of diastolic function (higher E/E' ratio than HT-/DM-, HT, or DM, all P < 0.05), independent of covariates. The negative, synergistic effect of hypertension and diabetes on LV diastolic function was present both in lean participants and in overweight/obese ones. An E/E' ratio >15, suggestive of increased LV filling pressure, was found in 2.2% of HT-/DM-, 8.9% of HT, 5.9% of DM, and 14.7% of HT + DM (P < 0.01).

CONCLUSION

Hypertension and diabetes are independently associated with impaired LV diastolic function, independent of the effect of overweight/obesity and other covariates. Their coexistence results in a negative synergistic effect on LV diastolic mechanics and is associated with higher LV filling pressures than either condition alone.

Risk Factors Associated with Left Ventricular Diastolic Dysfunction in Type 2 Diabetic Patients without Hypertension

Background

Hypertension and age are recognized as important risk factors for left ventricular (LV) diastolic dysfunction. Some studies have shown that diabetes itself may also be an independent risk factor for LV diastolic dysfunction, although this is controversial. The aim of this study was to determine the factors associated with LV diastolic dysfunction in patients with type 2 diabetes in the absence of hypertension or ischemic heart disease (IHD).

Methods

Participants in this study consisted of 65 type 2 diabetes patients (M : F = 45 : 20; mean age 51 [26 to 76] years; mean body mass index [BMI] 25.0 ± 2.5 kg/m²) without hypertension, heart disease, or renal disease. Individuals with ischemic electrocardiographic changes were excluded. LV diastolic function was evaluated by Doppler echocardiographic studies.

Results

Fifteen patients (23.1%) showed LV diastolic dysfunction on Doppler echocardiographic studies. Patients with LV diastolic dysfunction were older than those without diastolic dysfunction (60.0 ± 2.5 vs. 50.5 ± 1.9 years; P < 0.01). After adjusting for age and sex, BMI was higher (26.6 ± 0.7 vs. 24.6 ± 0.3 kg/m²; P < 0.01) and diabetes duration was longer (9.65 ± 1.48 vs. 4.71 ± 0.78 years; P < 0.01) in patients with LV diastolic dysfunction than in those without diastolic dysfunction. There were no differences in sex, smoking, blood pressure, lipid profiles, hemoglobin A₁C, fasting glucose, fasting insulin, or diabetic microvascular complications between the LV diastolic dysfunction group and the normal diastolic function group. After adjusting for age, sex, and BMI, diabetes duration was found to be independently associated with LV diastolic dysfunction (odds ratio 1.38; confidence interval 1.12 to 1.72; P = 0.003).

Conclusion

These results suggest that diabetes duration may be a risk factor for LV diastolic dysfunction in type 2 diabetic patients without hypertension or IHD.

The importance of γ-Glutamyltransferase (GGT) activity: a potential marker of Left Ventricular (LV) diastolic function in diabetic patients with cardiovascular disease

OBJECTIVES

To examine the relation between left ventricular (LV) diastolic function and γ-glutamyltransferase (GGT) in diabetic individuals with or without previously diagnosed cardiovascular disease.

DESIGN

A cross-sectional population-based study.

SETTING

A university hospital.

SUBJECTS

A total of 205 diabetic patients were included in the study. Patients who had cardiovascular disease constituted the study group (CD group; n = 112) and patients who had no complications constituted the control group (ND group; n = 93). Left ventricular diastolic function was assessed by pulsed Doppler tissue imaging and was determined by ratio E wave/A wave.

MAIN OUTCOME MEASURES

GGT levels were higher in CD Group than ND Group (25.9 ± 2.1 vs. 20.1 ± 1.5 units/L, p = 0.023). Significant difference between mean diastolic function parameters, such as E wave/A wave (0.86 ± 0.27 vs. 1.01 ± 0.36, p = 0.015), of the diabetic patients with and without cardiovascular disease was present. In this study, E wave/A wave correlated with age, waist-to-hip ratio (WHR), systolic blood pressure, and total cholesterol. Negative correlations were also found between LV diastolic function and GGT (β = -0.009, p = 0.008).

CONCLUSION

The data showed that in type 2 diabetic patients, with evident cardiac disease, metabolic parameters affect diastolic functions more than systolic functions. Besides known cardiovascular disease risk factors, GGT might be an additional marker of diastolic dysfunction in diabetes patients with cardiovascular disease.

Atherogenesis and atherothrombosis--focus on diabetes mellitus

Diabetes mellitus represents a major cause of cardiovascular morbidity and mortality in developed countries, and atherothrombosis accounts for most deaths among patients with diabetes mellitus. Atherothrombosis is defined as atherosclerotic lesion disruption with superimposed thrombus formation. As a long-term, progressive disease process, atherosclerosis often results in an acute atherothrombotic event through plaque rupture and formation of a platelet-rich thrombus. The principal clinical manifestations of atherothrombosis are sudden cardiac death, myocardial infarction, ischaemic stroke, and peripheral arterial ischaemia comprising both intermittent claudication and critical limb ischaemia. Atherosclerosis is the leading cause of morbidity and mortality in the industrialized world, and diabetes mellitus magnifies the risk of cardiovascular events. In addition to the well-known microvascular complications of diabetes mellitus - such as nephropathy, retinopathy and neuropathy - the risk of macrovascular complications affecting the large conduit arteries markedly increases in patients with diabetes mellitus.

A randomized trial of the impact of strict glycaemic control on myocardial diastolic function and perfusion reserve: a report from the DADD (Diabetes mellitus And Diastolic Dysfunction) study

AIMS

Myocardial diastolic dysfunction (MDD) and impaired coronary flow reserve (CFR) are early signs of myocardial involvement in patients with diabetes. The important question of whether this may be reversed by glucose normalization has not been tested in a controlled clinical trial. We hypothesized that strict glycaemic control, particularly if insulin based, will improve MDD and CFR.

METHODS AND RESULTS

Thirty-nine type 2 diabetes patients (mean age 61.0 +/- 7 years) with signs of diastolic dysfunction were randomly assigned to strict metabolic control by insulin (I-group; n = 21) or oral glucose lowering agents (O-group; n = 18). MDD and CFR were studied with Doppler-echocardiography including Tissue Doppler Imaging and myocardial contrast enhanced echocardiography. Fasting glucose (I-group = -2.2 +/- 2.1; O-group -1.5 +/- 0.8 mmol/L) and HbA(1c) were normalized (-0.6 +/- 0.4 and -0.7 +/- 0.4%, respectively) in both groups, but this did not significantly improve MDD in either of the groups (P = 0.65). There was no difference in CFR before and after improved glycaemic control.

CONCLUSION

The hypothesis that strict glycaemic control would reverse early signs of MDD and improve CFR in patients with type 2 diabetes could not be confirmed, despite achieved normalization. Whether it is possible to influence a more pronounced diastolic dysfunction, particularly in less well-controlled diabetic patients, remains to be established.

Comparison of outcome in catheter ablation of atrial fibrillation in patients with versus without the metabolic syndrome

Previous studies have reported that metabolic syndrome (MS) is associated with the development of atrial fibrillation (AF). However, its impact on the atrial substrate properties and catheter ablation in patients with AF is still unclear. This study consisted of 282 patients with AF (216 with paroxysmal AF and 66 with nonparoxysmal AF) who underwent catheter ablation using a 3-dimensional mapping system (NavX). Detailed AF mapping (frequency analysis and complex fractionated electrographic mapping) was performed in 59 patients. The patients were classified on the basis of MS, which was defined according to the guidelines of the National Cholesterol Education Program Adult Treatment Panel III. Patients with MS had larger left atrial sizes, shorter fractionated intervals, and higher dominant frequencies compared with those without it. Higher incidences of complex fractionated atrial electrographic sites located in the left atrial appendage base, coronary sinus, and crista terminalis regions were found in patients with MS. Patients with MS had a higher incidence of recurrent AF compared with those without MS (55% vs 24%, p <0.001). A higher incidence of recurrent AF from non-pulmonary vein origins was observed in patients with MS compared with those without it (45% vs 20%, p = 0.037). In conclusion, MS is associated with larger left atrial size and an arrhythmogenic substrate, which may increase the risk for recurrence after the ablation of AF. Close follow-up with good control of any metabolic disturbances may be needed in patients with MS to improve their outcomes after AF ablation.

Rosiglitazone, but not glimepiride, improves myocardial diastolic function in association with reduction in oxidative stress in type 2 diabetic patients without overt heart disease

The effects of thiazolidinediones on cardiac function are controversial in humans with type 2 diabetes (T2DM) and in animals. Given the high prevalence and prognostic relevance of diastolic myocardial dysfunction in T2DM, we tested the hypothesis that by reducing oxidative stress rosiglitazone, but not glimepiride, may improve diastolic function. This randomised cross-over study investigated 12 metformin-treated T2DM patients without cardiovascular disease before and after 16 weeks of additional therapy with rosiglitazone (8 mg daily) or glimepiride (3 mg daily). Systolic and diastolic myocardial velocity (E') were assessed with tissue Doppler. In spite of similar non-significant lowering of glycosylated haemoglobin (HbA1C), rosiglitazone, but not glimepiride, significantly improved E' (p=0.04), reduced malondialdehyde (p=0.028), lowered high-sensitivity C-reactive protein (hsCRP) (p=0.019), and increased adiponectin (p=0.002). For rosiglitazone, multivariate regression analysis revealed malondialdehyde reduction as an independent determinant of treatment-induced improvement in E'. The rosiglitazone-induced improvements of diastolic function and oxidative stress may be of prognostic relevance in choosing therapy for T2DM patients without overt heart disease.

Diastolic dysfunction: a link between hypertension and heart failure

Diastolic heart failure is characterized by the symptoms and signs of heart failure, a preserved ejection fraction and abnormal left ventricular (LV) diastolic function caused by a decreased LV compliance and relaxation. The signs and symptoms of diastolic heart failure are indistinguishable from those of heart failure related to systolic dysfunction; therefore, the diagnosis of diastolic heart failure is often one of exclusion. The majority of patients with heart failure and preserved ejection fraction have a history of hypertension. Hypertension induces a compensatory thickening of the ventricular wall in an attempt to normalize wall stress, which results in LV concentric hypertrophy, which in turn decreases LV compliance and LV diastolic filling. There is an abnormal accumulation of fibrillar collagen accompanying the hypertension-induced LV hypertrophy, which is also associated with decreased compliance and LV diastolic dysfunction. There are no specific guidelines for treating diastolic heart failure, but pharmacological treatment should be directed at normalizing blood pressure, promoting regression of LV hypertrophy, preventing tachycardia and treating symptoms of congestion. Preventive strategies directed toward an early and aggressive blood pressure control are likely to offer the greatest promise for reducing the incidence of diastolic heart failure.