Relation of hemoglobin A1c to left ventricular relaxation in patients with type 1 diabetes mellitus and without overt heart disease

Current Status and Potential Therapeutic Strategies for Using Non-coding RNA to Treat Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DMCM) is the leading cause of mortality and morbidity among diabetic patients. DMCM is characterized by an increase in oxidative stress with systemic inflammation that leads to cardiac fibrosis, ultimately causing diastolic and systolic dysfunction. Even though DMCM pathophysiology is well studied, the approach to limit this condition is not met with success. This highlights the need for more knowledge of underlying mechanisms and innovative therapies. In this regard, emerging evidence suggests a potential role of non-coding RNAs (ncRNAs), including micro-RNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) as novel diagnostics, mechanisms, and therapeutics in the context of DMCM. However, our understanding of ncRNAs’ role in diabetic heart disease is still in its infancy. This review provides a comprehensive update on pre-clinical and clinical studies that might develop therapeutic strategies to limit/prevent DMCM.

Diabetic cardiomyopathy - A comprehensive updated review

Diabetes causes cardiomyopathy and increases the risk of heart failure independent of hypertension and coronary heart disease. This condition called "Diabetic Cardiomyopathy" (DCM) is becoming a well- known clinical entity. Recently, there has been substantial research exploring its molecular mechanisms, structural and functional changes, and possible development of therapeutic approaches for the prevention and treatment of DCM. This review summarizes the recent advancements to better understand fundamental molecular abnormalities that promote this cardiomyopathy and novel therapies for future research. Additionally, different diagnostic modalities, up to date screening tests to guide clinicians with early diagnosis and available current treatment options has been outlined.

Data Linking Diabetes Mellitus and Atrial Fibrillation-How Strong Is the Evidence? From Epidemiology and Pathophysiology to Therapeutic Implications

According to estimates, around 5% of the world population has hazel eyes. And there are about as many people with diabetes mellitus (DM). Red hair occurs naturally in up to 2% of the human population. And about as many people are estimated to have atrial fibrillation (AF). If a hazel eyed person with red hair does not surprise us, should a diabetic patient with AF? Accumulating epidemiologic data suggest, however, that the DM-AF association may be more than a simple coincidence. But, how strong is this evidence? Experimental studies bring evidence for a DM-induced atrial proarrhythmic remodelling. But how relevant are these data for the clinical setting? In this review, we aim to provide a critical analysis of the existing clinical and experimental, epidemiologic, and mechanistic data that bridge DM and AF, we emphasize a number of questions that remain to be answered, and we identify hotspots for future research. The therapeutic implications of the DM-AF coexistence are also discussed, with a focus on rhythm control and on conventional and DM-specific upstream therapies for AF management.

Pathophysiological Fundamentals of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) was first recognized more than four decades ago and occurred independent of cardiovascular diseases or hypertension in both type 1 and type 2 diabetic patients. The exact mechanisms underlying this disease remain incompletely understood. Several pathophysiological bases responsible for DCM have been proposed, including the presence of hyperglycemia, nonenzymatic glycosylation of large molecules (e.g., proteins), energy metabolic disturbance, mitochondrial damage and dysfunction, impaired calcium handling, reactive oxygen species formation, inflammation, cardiac cell death, and cardiac hypertrophy and fibrosis, leading to impairment of cardiac contractile functions. Increasing evidence also indicates the phenomenon called "metabolic memory" for diabetes-induced cardiovascular complications, for which epigenetic modulation seemed to play an important role, suggesting that the aforementioned pathogenic bases may be regulated by epigenetic modification. Therefore, this review aims at briefly summarizing the current understanding of the pathophysiological bases for DCM. Although how epigenetic mechanisms play a role remains incompletely understood now, extensive clinical and experimental studies have implicated its importance in regulating the cardiac responses to diabetes, which are believed to shed insight into understanding of the pathophysiological and epigenetic mechanisms for the development of DCM and its possible prevention and/or therapy. © 2017 American Physiological Society. Compr Physiol 7:693-711, 2017.

Impact of type 2 diabetes on cardiorespiratory function and exercise performance

The aim of this study was to examine the impact of well‐controlled uncomplicated type 2 diabetes (T2D) on exercise performance. Ten obese sedentary men with T2D and nine control participants without diabetes matched for age, sex, and body mass index were recruited. Anthropometric characteristics, blood samples, resting cardiac, and pulmonary functions and maximal oxygen uptake (VO_2max) and ventilatory threshold were measured on a first visit. On the four subsequent visits, participants (diabetics: n = 6; controls: n = 7) performed step transitions (6 min) of moderate‐intensity exercise on an upright cycle ergometer from unloaded pedaling to 80% of ventilatory threshold. VO₂ (τVO₂) and HR (τHR) kinetics were characterized with a mono‐exponential model. VO_2max (27.0 ± 3.4 vs. 26.7 ± 5.0 mL kg⁻¹ min⁻¹; P = 0.85), τVO₂ (43 ± 6 vs. 43 ± 10 sec; P = 0.73), and τHR (42 ± 17 vs. 43 ± 13 sec; P = 0.94) were similar between diabetics and controls respectively. The remaining variables were also similar between groups, with the exception of lower maximal systolic blood pressure in diabetics (P = 0.047). These results suggest that well‐controlled T2D is not associated with a reduction in VO_2max or slower τVO₂ and τHR.

The effects of type 1 diabetes mellitus on cardiac functions in children: evaluation by conventional and tissue Doppler echocardiography

BACKGROUND

Several studies have pointed out the existence of cardiac dysfunction in patients with type 1 diabetes mellitus (DM) even in the absence of ischemic, valvular, or hypertensive heart disease. The present study evaluated cardiac dysfunction and the relationship between severity of disease and degree of cardiac dysfunction in children with type 1 DM.

METHODS

In this prospective study, 31 patients with type 1 DM and 33 sex- and age-matched healthy children were evaluated with conventional echocardiography and tissue Doppler echocardiography (TDE). A correlation between cardiac functions and glycated hemoglobin (HbA1C) was examined.

RESULTS

TDE results indicated that mitral valve early diastolic annular peak flow rate (E'), mitral valve systolic flow rate (S'), ratio of mitral valve early diastolic peak flow rate to mitral valve early diastolic annular peak flow rate (E/E'), and left ventricular (LV) myocardial performance index (MPI) were higher, and LV ejection time (ET) was shorter in patients with type 1 DM (p<0.05). In addition, tricuspid valve E' and right ventricular (RV) MPI were higher, while RV ET and tricuspid E/E' were lower in patients with type 1 DM compared to healthy children (p<0.05).

CONCLUSIONS

Although conventional echocardiography revealed no difference between patients with type 1 DM and healthy children, TDE showed dysfunctions of both ventricles. This state is closely related to degree of blood glucose level control. These findings signify diagnostic value of TDE in the early detection of cardiac effects among patients with type 1 DM.

Cardiomyocyte GTP Cyclohydrolase 1 Protects the Heart Against Diabetic Cardiomyopathy

Diabetic cardiomyopathy increases the risk of heart failure and death. At present, there are no effective approaches to preventing its development in the clinic. Here we report that reduction of cardiac GTP cyclohydrolase 1 (GCH1) degradation by genetic and pharmacological approaches protects the heart against diabetic cardiomyopathy. Diabetic cardiomyopathy was induced in C57BL/6 wild-type mice and transgenic mice with cardiomyocyte-specific overexpression of GCH1 with streptozotocin, and control animals were given citrate buffer. We found that diabetes-induced degradation of cardiac GCH1 proteins contributed to adverse cardiac remodeling and dysfunction in C57BL/6 mice, concomitant with decreases in tetrahydrobiopterin, dimeric and phosphorylated neuronal nitric oxide synthase, sarcoplasmic reticulum Ca(2+) handling proteins, intracellular [Ca(2+)]i, and sarcoplasmic reticulum Ca(2+) content and increases in phosphorylated p-38 mitogen-activated protein kinase and superoxide production. Interestingly, GCH-1 overexpression abrogated these detrimental effects of diabetes. Furthermore, we found that MG 132, an inhibitor for 26S proteasome, preserved cardiac GCH1 proteins and ameliorated cardiac remodeling and dysfunction during diabetes. This study deepens our understanding of impaired cardiac function in diabetes, identifies GCH1 as a modulator of cardiac remodeling and function, and reveals a new therapeutic target for diabetic cardiomyopathy.

Relationship between increased left atrial volume and microvascular complications in patients with type 2 diabetes

AIMS

We assessed whether left atrial volume index (LAVI) was associated with the presence of microvascular complications in patients with type 2 diabetes, and whether this association was independent of hemodynamic and non-hemodynamic factors.

METHODS

We studied 157 consecutive outpatients with type 2 diabetes with no previous history of ischemic heart disease, chronic heart failure and valvular diseases. A transthoracic echocardiography and myocardial perfusion scintigraphy were performed in all participants. Presence of microvascular complications was also recorded.

RESULTS

Overall, 51 patients had decreased estimated glomerular filtration rate and/or abnormal albuminuria, 24 had diabetic retinopathy, 22 had lower-extremity sensory neuropathy, and 67 (42.7%) patients had one or more of these microvascular complications (i.e., combined endpoint). After stratifying patients by LAVI, those with LAVI ≥32 ml/m(2) had a greater prevalence of microvascular complication, lower left ventricular (LV) ejection fraction, higher LV mass index and higher E/e' ratio than those with LAVI <32 ml/m(2). Logistic regression analyses revealed that microvascular complications (singly or in combination) were associated with increased LAVI, independently of age, sex, diabetes duration, hemoglobin A1c, hypertension, LV-ejection fraction, LV mass index and the E/e' ratio.

CONCLUSIONS

These results indicate that microvascular diabetic complications are associated with increased LAVI in well-controlled type 2 diabetic patients with preserved systolic function and free from ischemic heart disease, independently of multiple potential confounders.

Diabetic Cardiomyopathy; Summary of 41 Years

Patients with diabetes have an increased risk for development of cardiomyopathy, even in the absence of well known risk factors like coronary artery disease and hypertension. Diabetic cardiomyopathy was first recognized approximately four decades ago. To date, several pathophysiological mechanisms thought to be responsible for this new entity have also been recognized. In the presence of hyperglycemia, non-enzymatic glycosylation of several proteins, reactive oxygen species formation, and fibrosis lead to impairment of cardiac contractile functions. Impaired calcium handling, increased fatty acid oxidation, and increased neurohormonal activation also contribute to this process. Demonstration of left ventricular hypertrophy, early diastolic and late systolic dysfunction by sensitive techniques, help us to diagnose diabetic cardiomyopathy. Traditional treatment of heart failure is beneficial in diabetic cardiomyopathy, but specific strategies for prevention or treatment of cardiac dysfunction in diabetic patients has not been clarified yet. In this review we will discuss clinical and experimental studies focused on pathophysiology of diabetic cardiomyopathy, and summarize diagnostic and therapeutic approaches developed towards this entity.

Worsening diastolic function is associated with elevated fasting plasma glucose and increased left ventricular mass in a supra-additive fashion in an elderly, healthy, Swedish population

AIMS

To examine whether increasing fasting plasma glucose (FPG) levels were associated with worsening left ventricular (LV) diastolic function, independently of LV mass index (LVMI) in elderly, otherwise healthy subjects.

METHODS AND RESULTS

We tested cross-sectional associations between echocardiographically determined averaged E/é ratio/diastolic function, LVMI, cardiovascular risk factors, and FPG categorized as normal (NFG), impaired (IFG), and new-onset diabetes mellitus (DM), in 483 men and 208 women aged 56-79 years without overt cardiovascular disease, who received no cardiovascular, anti-diabetic, or lipid-lowering drugs and had a preserved LV ejection fraction >50%. Median E/é was significantly higher among subjects with diabetes than those without (8 vs. 7; p = 0.03), as was the prevalence of grade 2 or 3 diastolic dysfunction (25% vs. 16%; p = 0.02). E/é and diastolic function were significantly associated with LVMI (p ≤ 0.002), but not FPG category, on multivariable analysis. However, interaction analyses revealed that increasing LVMI was primarily associated with worsening diastolic function (higher E/é) in subjects with FPG > 6 mmol/L (β=0.005 for IFG and DM vs. 0.001 for NFG; p = 0.02), whereas increasing systolic blood pressure was primarily associated with worsening diastolic function (higher E/é) in subjects with FPG ≤ 6.9 mmol/L (β = 0.005 for NFG and 0.003 for IFG vs. -0.001 for DM; p=0.001).

CONCLUSION

Diastolic dysfunction was significantly more prevalent among patients with DM than those without. The importance of LVMI increased, but the importance of systolic blood pressure decreased with higher FPG category.

Time-course changes in left ventricular myocardial deformation in STZ-induced rabbits on velocity vector imaging

OBJECTIVES

To clarify the time-course changes in left ventricular myocardial deformation using velocity vector imaging and to provide insights into our understanding of the cardiac pathophysiology in diabetes mellitus.

METHODS

Thirty New Zealand white rabbits were randomly divided into either the control group (n = 10) or the diabetes mellitus (DM) group (induced with STZ, n = 20). For the myocardial deformation studies, echocardiography and syngo-vector velocity imaging (VVI) were performed at baseline and after 2, 4, 8, and 12 weeks in all of the rabbits. The left ventricular (LV) global longitudinal and circumferential strain and strain rate were measured. For histomorphological study of the heart structure, 2 of the STZ-induced rabbits were killed at 2, 4, 8, and 12 weeks. Routine hematoxylin and eosin staining was performed.

RESULTS

At 2 weeks, the global longitudinal strain (GLS), systolic strain rate (GLSRs), and diastolic strain rate (GLSRd) were significantly lower in the DM group compared with the control group (-18.16% versus -24.00%, -1.86 s(-1) versus -2.49 s(-1), 1.93 s(-1) versus 2.42 s(-1), respectively, P < 0.05), while, compared with the control group, the global circumferential strain (GCS), systolic strain rate (GCSRs), and diastolic strain rate (GCSRd) in the DM group were significantly decreased (-12.77% versus -23.31%, -1.31 s(-1) versus -2.20 s(-1), 1.41 s(-1) versus 2.15 s(-1), respectively, P < 0.05) at 8 weeks. With the progression of untreated diabetes, the histoanatomical alterations intensified gradually beginning at 2 weeks.

CONCLUSIONS

The progressive impairments in LV myocardial deformation and structure occurred early in diabetic rabbits with normal LV ejection fraction (EF), FS, and E/A. VVI could be used to evaluate subtle cardiac dysfunction in the early phase of DM.

Impaired left ventricular function and myocardial blood flow reserve in patients with long-term type 1 diabetes and no significant coronary artery disease: associations with protein glycation

Our aims were to study left ventricular (LV) function and myocardial blood flow reserve (MBFR) in long-term type 1 diabetes and associations with advanced glycation end products (AGEs). A total of 20 type 1 diabetes patients from the Oslo Study without significant stenosis on coronary angiography were compared with 26 controls. LV systolic and diastolic functions were assessed by two-dimensional strain and the ratio between pulsed Doppler transmitral early (E) velocity and tissue Doppler velocity (E'), respectively. MBFR was evaluated by contrast echocardiography. The AGE methylglyoxal-derived hydroimidazolone was analysed in serum. Glyoxal hydroimidazolone in skin collagen was determined by liquid chromatography-mass spectrometry. Strain was significantly reduced (-19.5% ± 1.9% vs -21.4% ± 3.5%, p < 0.05), and E/E' increased in the diabetes patients compared to controls, 7.3 ± 2 versus 6.0 ± 1.5, p < 0.05. Significant lower MBFR was present in the diabetes patients, 3.4 (2.1, 5.3) versus 5.9 (3.9, 9.6), p < 0.01. Both AGEs correlated significantly with E/E'. The impaired LV function with correlation to AGEs in concert with reduced MBFR in diabetics without coronary artery disease may indicate possible mechanisms for diabetic cardiomyopathy.

Effects of prior intensive versus conventional therapy and history of glycemia on cardiac function in type 1 diabetes in the DCCT/EDIC

Intensive diabetes therapy reduces the prevalence of coronary calcification and progression of atherosclerosis and the risk of cardiovascular disease (CVD) events in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study. The effects of intensive therapy on measures of cardiac function and structure and their association with glycemia have not been explored in type 1 diabetes (T1DM). We assess whether intensive treatment compared with conventional treatment during the DCCT led to differences in these parameters during EDIC. After 6.5 years of intensive versus conventional therapy in the DCCT, and 15 years of additional follow-up in EDIC, left ventricular (LV) indices were measured by cardiac magnetic resonance (CMR) imaging in 1,017 of the 1,371 members of the DCCT cohort. There were no differences between the DCCT intensive versus conventional treatment in end diastolic volume (EDV), end systolic volume, stroke volume (SV), cardiac output (CO), LV mass, ejection fraction, LV mass/EDV, or aortic distensibility (AD). Mean DCCT/EDIC HbA1c over time was associated with EDV, SV, CO, LV mass, LV mass/EDV, and AD. These associations persisted after adjustment for CVD risk factors. Cardiac function and remodeling in T1DM assessed by CMR in the EDIC cohort was associated with prior glycemic exposure, but there was no effect of intensive versus conventional treatment during the DCCT on cardiac parameters.

Diabetic cardiomyopathy: pathophysiology and clinical features

Since diabetic cardiomyopathy was first reported four decades ago, substantial information on its pathogenesis and clinical features has accumulated. In the heart, diabetes enhances fatty acid metabolism, suppresses glucose oxidation, and modifies intracellular signaling, leading to impairments in multiple steps of excitation–contraction coupling, inefficient energy production, and increased susceptibility to ischemia/reperfusion injury. Loss of normal microvessels and remodeling of the extracellular matrix are also involved in contractile dysfunction of diabetic hearts. Use of sensitive echocardiographic techniques (tissue Doppler imaging and strain rate imaging) and magnetic resonance spectroscopy enables detection of diabetic cardiomyopathy at an early stage, and a combination of the modalities allows differentiation of this type of cardiomyopathy from other organic heart diseases. Circumstantial evidence to date indicates that diabetic cardiomyopathy is a common but frequently unrecognized pathological process in asymptomatic diabetic patients. However, a strategy for prevention or treatment of diabetic cardiomyopathy to improve its prognosis has not yet been established. Here, we review both basic and clinical studies on diabetic cardiomyopathy and summarize problems remaining to be solved for improving management of this type of cardiomyopathy.

Serum adiponectin and hsCRP levels and non-invasive radiological methods in the early diagnosis of cardiovascular system complications in children and adolescents with type 1 diabetes mellitus

OBJECTIVE

Adiponectin and high-sensitivity C-reactive protein (hsCRP) can be used as early biochemical markers of cardiovascular diseases (CVDs). Radiologically, non-invasive flow-mediated dilation (FMD) of the brachial artery and carotid intima-media thickness (CIMT) measurements may be used as indicators in the early diagnosis of CVDs. To compare the biochemical markers of atherosclerosis with radiological markers of CVDs (CIMT, FMD, ventricular systolic and diastolic functions) and to assess the relationship of these parameters with metabolic control in diabetic children and adolescents.

METHODS

A total of 55 patients with type 1 diabetes mellitus (T1DM) of at least 5-year duration and 30 healthy subjects were included in the study. Serum adiponectin, hsCRP, hemoglobin A1c (HbA1c), and lipid levels were evaluated in the patients and in the controls. CIMT, FMD, ventricular systolic and diastolic functions were assessed by echocardiography.

RESULTS

Mean age of the patients with diabetes was 17.6 years; mean diabetes duration was 10.4 years. Mean serum hsCRP was elevated in children with diabetes (0.21±0.31 vs. 0.10±0.16 μg/mL, p=0.00), while no significant difference from the controls was found in adiponectin levels. Mean CIMT was significantly higher in diabetic children compared to the control group (0.53±0.11 vs. 0.34±0.46 mm, p=0.00). Mean FMD of the diabetic children was significantly lower than that of the controls (6.86±2.85% vs. 12.13±1.99%, p=0.00). Diabetes duration was positively correlated with CIMT and negatively correlated with FMD. Right ventricular (RV) and left ventricular (LV) myocardial performance index (MPI) were higher in the patient group (p=0.00).

CONCLUSIONS

Our data suggest that in addition to standard echocardiography, tissue Doppler echocardiography, FMD, and CIMT can be used as early-stage radiological markers and hsCRP as an early-stage biochemical marker of atherosclerosis in the routine follow-up of T1DM patients.

Diabetic cardiomyopathy: understanding the molecular and cellular basis to progress in diagnosis and treatment

Diabetes mellitus is an important and prevalent risk factor for congestive heart failure. Diabetic cardiomyopathy has been defined as ventricular dysfunction that occurs in diabetic patients independent of a recognized cause such as coronary artery disease or hypertension. The disease course consists of a hidden subclinical period, during which cellular structural insults and abnormalities lead initially to diastolic dysfunction, later to systolic dysfunction, and eventually to heart failure. Left ventricular hypertrophy, metabolic abnormalities, extracellular matrix changes, small vessel disease, cardiac autonomic neuropathy, insulin resistance, oxidative stress, and apoptosis are the most important contributors to diabetic cardiomyopathy onset and progression. Hyperglycemia is a major etiological factor in the development of diabetic cardiomyopathy. It increases the levels of free fatty acids and growth factors and causes abnormalities in substrate supply and utilization, calcium homeostasis, and lipid metabolism. Furthermore, it promotes excessive production and release of reactive oxygen species, which induces oxidative stress leading to abnormal gene expression, faulty signal transduction, and cardiomyocytes apoptosis. Stimulation of connective tissue growth factor, fibrosis, and the formation of advanced glycation end-products increase the stiffness of the diabetic hearts. Despite all the current information on diabetic cardiomyopathy, translational research is still scarce due to limited human myocardial tissue and most of our knowledge is extrapolated from animals. This paper aims to elucidate some of the molecular and cellular pathophysiologic mechanisms, structural changes, and therapeutic strategies that may help struggle against diabetic cardiomyopathy.

Diastolic function is reduced in adolescents with type 1 diabetes in response to exercise

OBJECTIVE

To determine whether adolescents with type 1 diabetes have left ventricular functional changes at rest and during acute exercise and whether these changes are affected by metabolic control and diabetes duration.

RESEARCH DESIGN AND METHODS

The study evaluated 53 adolescents with type 1 diabetes and 22 control adolescents. Baseline data included peak exercise capacity and body composition by dual-energy X-ray absorptiometry. Left ventricular functional parameters were obtained at rest and during acute exercise using magnetic resonance imaging.

RESULTS

Compared with nondiabetic control subjects, adolescents with type 1 diabetes had lower exercise capacity (44.7 ± 09 vs. 48.5 ± 1.4 mL/kg fat-free mass [FFM]/min; P < 0.05). Stroke volume was reduced in the diabetes group at rest (1.86 ± 0.04 vs. 2.05 ± 0.07 mL/kg FFM; P = 0.02) and during acute exercise (1.89 ± 0.04 vs. 2.17 ± 0.06 mL/kg FFM; P = 0.01). Diabetic adolescents also had reduced end-diastolic volume at rest (2.94 ± 0.06 vs. 3.26 ± 0.09 mL/kg FFM; P = 0.01) and during acute exercise (2.78 ± 0.05 vs. 3.09 ± 0.08 mL/kg FFM; P = 0.01). End-systolic volume was lower in the diabetic group at rest (1.08 ± 0.03 vs. 1.21 ± 0.04 mL/kg FFM; P = 0.01) but not during acute exercise. Exercise capacity and resting and exercise stroke volumes were correlated with glycemic control but not with diabetes duration.

CONCLUSIONS

Adolescents with type 1 diabetes have reduced exercise capacity and display alterations in cardiac function compared with nondiabetic control subjects, associated with reduced stroke volume during exercise.

Diastolic dysfunction and heart failure with a preserved ejection fraction: Relevance in critical illness and anaesthesia

Epidemiological and clinical studies suggest that HF with a preserved ejection fraction will become the more common form of HF which clinicians will encounter. The spectrum of diastolic disease extends from the asymptomatic phase to fulminant cardiac failure. These patients are commonly encountered in operating rooms and critical care units. A clearer understanding of the underlying pathophysiology and clinical implications of HF with a preserved ejection fraction is fundamental to directing further research and to evaluate interventions. This review highlights the impact of diastolic dysfunction and HF with a preserved ejection fraction during the perioperative period and during critical illness.

Cardiac structure and function, remodeling, and clinical outcomes among patients with diabetes after myocardial infarction complicated by left ventricular systolic dysfunction, heart failure, or both

AIMS

The mechanisms responsible for the increased risk of heart failure (HF) post-myocardial infarction (MI) may differ between patients with versus without diabetes. We hypothesized that after high-risk MI, patients with diabetes would demonstrate patterns of remodeling that are suggestive of reduced ventricular compliance and that are associated with an increased risk of death or HF.

METHODS AND RESULTS

We performed quantitative echocardiographic analysis in 153 patients with diabetes and 451 patients without diabetes enrolled in the VALIANT Echo study. Diabetes was associated with a higher risk of death or HF in age-adjusted models (hazard ratio 1.44, 95% CI 1.04-2.00, P = .028). Diabetic patients were similar to nondiabetic patients with respect to left ventricular (LV) volume and ejection fraction but had higher LV mass index (104.1 ± 27.5 vs 97.1 ± 28.6 g/m(2), P = .009), relative wall thickness (0.41 ± 0.08 vs 0.38 ± 0.07, P < .0001), and left atrial volume index (LAVi) (26.2 ± 8.1 vs 24.0 ± 8.2 mL/m(2), P = .008)-all parameters that were significantly related to the risk of death or HF hospitalization. Changes in LV volume and ejection fraction from baseline to 20 months were not different, although diabetic patients demonstrated greater increase in LAVi (4.4 ± 7.7 vs 2.2 ± 6.7 mL/m(2), P = .01).

CONCLUSIONS

After high-risk MI, diabetic patients were at higher risk of death or HF and demonstrated greater baseline LV mass index, relative wall thickness, and LAVi as well as greater left atrial enlargement at 20-month follow-up. These findings suggest greater baseline concentric remodeling and long-term elevation in LV diastolic pressure post-MI among diabetic patients, which may partially mediate this risk.

Left ventricular systolic and diastolic function, remodelling, and clinical outcomes among patients with diabetes following myocardial infarction and the influence of direct renin inhibition with aliskiren

AIMS

We assessed the relationship between diabetes and cardiac structure and function following myocardial infarction (MI) and whether diabetes influences the effect of direct renin inhibition on change in left ventricular (LV) size.

METHODS AND RESULTS

The ASPIRE trial enrolled 820 patients 2-8 weeks after MI with ejection fraction ≤ 45% and randomized them to the direct renin inhibitor aliskiren (n= 423) or placebo (n = 397) added to standard medical therapy. Echocardiography was performed at baseline and after 36 weeks in 672 patients with evaluable paired studies. Compared with non-diabetic patients, diabetic patients (n = 214) were at higher risk for a composite of cardiovascular (CV) death, heart failure hospitalization, recurrent MI, stroke, or aborted sudden death (14 vs. 7%; adjusted hazard ratio 1.63, 95% confidence interval 1.01-2.64, P= 0.045), despite similar left ventricular ejection fraction (37.9 ± 5.3 vs. 37.6 ± 5.2%, P= 0.48) and end-systolic volume (ESV) (84 ± 25 vs. 82 ± 28 mL, P= 0.46). Diabetic patients demonstrated greater concentric remodelling (relative wall thickness 0.38 ± 0.07 vs. 0.36 ± 0.07, P= 0.0002) and evidence of higher LV filling pressure (E/E' 11.1 ± 5.3 vs. 9.1 ± 4.3, P= 0.0011). At 36 weeks, diabetic patients experienced similar per cent reduction in ESV overall (-4.9 ± 17.9 vs. -5.5 ± 16.9, P= 0.67) but tended to experience greater reduction in ESV than non-diabetic patients when treated with aliskiren (interaction P = 0.08).

CONCLUSIONS

Compared with non-diabetic patients, diabetic patients are at increased risk of CV events post-MI despite no greater LV enlargement or reduction in systolic function. Diabetic patients demonstrate greater concentric remodelling and evidence of higher LV filling pressure, suggesting diastolic dysfunction as a potential mechanism for the higher risk observed among these patients.

Relationship Between Early Diastolic Dysfunction and Abnormal Microvolt T-Wave Alternans in Patients With Type 2 Diabetes

Background—

Abnormal microvolt T-wave alternans (MTWA), a marker of ventricular arrhythmic risk, is a highly prevalent condition in patients with type 2 diabetes mellitus (T2DM) and is correlated with glycemic control. However, there is uncertainty as to whether central or peripheral hemodynamic factors are associated with abnormal MTWA in T2DM individuals.

Methods and Results—

We studied 50 consecutive, well-controlled T2DM outpatients without a history of ischemic heart disease and with normal systolic function. All patients underwent a complete echocardiographic Doppler evaluation with spectral tissue Doppler analysis. MTWA analysis was performed noninvasively during submaximal exercise. Effective arterial elastance, arterial compliance, and heart rate variability were also measured. Compared with patients with MTWA negativity (n=38), those with MTWA abnormality (n=12, 24%) had significantly lower e′ (7.6±1.3 versus 9.1±1.7 cm/s; P <0.01), a′ (10.2±1.6 versus 12.7±1.9 cm/s; P <0.001) and s′ velocities (8.7±1.1 versus 10.2±1.5 cm/s; P =0.001) and higher indexed left ventricular mass (121.3±16.4 versus 107.5±16.5 g/m 2 ; P =0.016), indexed left atrial volume (33.5±11.9 versus 23.6±5.6 mL/m 2 ; P <0.001), and E/e′ ratio (8.8±1.4 versus 6.5±1.3; P <0.001). Multivariable logistic regression analysis revealed that higher E/e′ ratio was the only independent correlate of abnormal MTWA (adjusted odds ratio, 3.52; 95% confidence interval, 1.19 to 10.6; P =0.02) after controlling for glycemic control and other potential confounders.

Conclusions—

In this pilot study, we found that early diastolic dysfunction, as measured by tissue Doppler imaging, is independently associated with MTWA abnormality in T2DM individuals with normal systolic function. Further larger studies are needed to examine the reproducibility of these results.

The impact of early diastolic myocardial relaxation on the other parameters of diastolic function and association of tissue Doppler parameters of diastolic function with diabetes compensation and duration in type 2 diabetic patients

This study assessed the impact of tissue Doppler derived myocardial early diastolic relaxation velocity (E(m)) on the other parameters of diastolic function (preload dependent transmitral early diastolic velocity [E], tissue Doppler derived myocardial late diastolic velocity [A(m)], preload dependent transmitral late diastolic velocity [A]) and evaluated the correlation of these parameters with selected clinical variables in type 2 diabetic patients. Using tissue Doppler echocardiography, 82 type 2 diabetic patients were evaluated, divided into two equal groups of E(m) < 7.5 cm/s or > or = 7.5 cm/s. Patients with E(m) < 7.5 cm/s had significantly lower E/A and E(m)/A(m), and higher E/E(m) values. Multilinear regression showed a negative correlation between E(m) and glycated haemoglobin (Hb(A1c)) and duration of diabetes, a negative correlation of E(m)/A(m) with age, duration of diabetes and Hb(A1c), and a positive correlation of E/E(m) with age, duration of diabetes and use of diuretics. The E/A ratio only correlated negatively with age. It is concluded that E(m) is a reliable parameter of diastolic function, and that the tissue Doppler parameters of diastolic function are associated with diabetes compensation and diabetes duration.

Diabetic cardiomyopathy

Diabetic cardiomyopathy is a distinct primary disease process, independent of coronary artery disease, which leads to heart failure in diabetic patients. Epidemiological and clinical trial data have confirmed the greater incidence and prevalence of heart failure in diabetes. Novel echocardiographic and MR (magnetic resonance) techniques have enabled a more accurate means of phenotyping diabetic cardiomyopathy. Experimental models of diabetes have provided a range of novel molecular targets for this condition, but none have been substantiated in humans. Similarly, although ultrastructural pathology of the microvessels and cardiomyocytes is well described in animal models, studies in humans are small and limited to light microscopy. With regard to treatment, recent data with thiazoledinediones has generated much controversy in terms of the cardiac safety of both these and other drugs currently in use and under development. Clinical trials are urgently required to establish the efficacy of currently available agents for heart failure, as well as novel therapies in patients specifically with diabetic cardiomyopathy.

Diabetic myocardial disease: pathophysiology, early diagnosis and therapeutic options

Diabetes mellitus is a powerful risk factor for cardiovascular disease associated with high morbidity and mortality rates. Diabetic patients also have an increased incidence of heart failure which has been traditionally attributed to the concurrent presence of ischemic or hypertensive heart disease. Yet, nowadays, according to recent scientific evidence, diabetic myocardial disease (DMD) is more and more being considered as a distinct nosologic entity, independent of the co-existence of coronary artery disease, arterial hypertension or other risk factors, with the potential to lead to a self-existent progressive development of heart failure. In this article, we review the possible pathophysiologic mechanisms involved in the development of DMD as well as the structural and functional changes in the diabetic heart. We emphasize the importance of early detection of the syndrome, especially by novel echocardiographic techniques. Finally, we refer to the various therapeutic options for the optimal management of DMD according to the recent literature.

Diabetic cardiomyopathy--a distinct disease?

Diabetic individuals have a significantly increased likelihood of developing cardiovascular disease. Whilst part of this association is explained by the presence of concomitant risk factors, large epidemiological studies have consistently reported diabetes as a strong risk factor for the development of heart failure after adjusting for such covariates. This has resulted in the notion that there is a distinct cardiomyopathy specific to diabetes, termed 'diabetic cardiomyopathy'. The natural history is characterized by a latent subclinical period, during which there is evidence of diastolic dysfunction and left ventricular hypertrophy, before overt clinical deterioration and systolic failure ensue. These clinical findings have been supported by a growing body of experimental data which support the notion that diabetes inflicts a direct insult to the myocardium, with cellular, structural and functional changes manifest as the diabetic myocardial phenotype. Several of these mechanisms appear to work in unison, forming complicated reciprocal pathways of disease. Reactive oxygen species and alterations in intracellular calcium homeostasis appear to play significant roles in many of these mechanisms. Determining the hierarchy of this cascade of disease will allow identification of the pathological trigger most responsible for disease. Translational research in this field is currently hindered by a lack of clinical studies and intervention trials specifically in patients with diabetic cardiomyopathy. Future clinical and experimental studies of accurate models of diabetic cardiomyopathy should help to define the true aetiology and lead to the development of specific pharmacotherapies for this condition, ultimately reducing the increased cardiovascular morbidity and mortality in diabetic patients.

Assessment of atrial electromechanical delay, diastolic functions, and left atrial mechanical functions in patients with type 1 diabetes mellitus

OBJECTIVE

The aim of this study was to evaluate atrial electromechanical coupling obtained by tissue Doppler imaging (TDI), left and right ventricular diastolic functions, and left atrial (LA) mechanical functions in patients with type 1 diabetes mellitus (DM-1).

METHODS

A total of 43 patients with DM-1 (age 19.6 +/- 6.8 years) and 42 age- and gender-matched controls (age 19.5 +/- 6.4 years) were included. Atrial electromechanical coupling was measured with TDI and corrected for heart rate. P-wave dispersion (Pd) was calculated from the 12-lead electrocardiograms. Systolic and diastolic functions in both ventricles were assessed using conventional echocardiography and TDI. Myocardial performance index was calculated with TDI. LA maximal, minimal, and pre-systolic volumes were measured according to the biplane area-length method. LA mechanical function parameters were calculated.

RESULTS

Intra- and interatrial electromechanical delays and Pd were significantly higher in patients with DM-1 compared with controls (P = .02, P < .0001, and P = 0.005, respectively). A-wave velocity and isovolumic relaxation time were higher and E/A ratio was lower in patients with DM-1 (P = .03, P = .03, and P = .003, respectively). According to TDI, systolic velocities and myocardial performance index values of both ventricles were comparable. Diastolic filling velocities of the left ventricle, including E(m) global, A(m) global, E(m)/A(m) ratio, and right ventricular A(m), were different between groups (P = .03, P = .02, P < .001, and P = .02, respectively). LA passive emptying fraction was decreased, and LA active emptying volume and LA active emptying fraction were increased in patients with DM-1 (P = .02, P = .001, and P < .0001, respectively). Interatrial electromechanical delay was positively correlated with the presence of DM-1, age, LA active emptying fraction, and Pd (P < .001, P = .007, P < .001, and P = .002, respectively), and was negatively correlated with E(m)/A(m) ratio and LA passive emptying fraction (P < .001 and P = .001, respectively). In multivariate analyses, age and DM-1 were independent predictors of interatrial electromechanical delay (P = .001 and P < .001, respectively).

CONCLUSION

This study shows that intra- and interatrial electromechanical delays are prolonged diastolic functions of both ventricles and that LA mechanical functions are impaired in patients with DM-1. Age and the presence of DM-1 were independent factors of the interatrial electromechanical delay.

Impact of statin therapy on left ventricular function and carotid arterial stiffness in patients with hypercholesterolemia

BACKGROUND

Hypercholesterolemia is a well-established risk factor for the development of vascular events. Statins have pleiotropic effects beyond reducing the low-density lipoprotein-cholesterol (LDL-C) concentration. This study sought to determine whether treatment with pitavastatin affects latent regional left ventricular (LV) systolic and diastolic dysfunction and carotid arterial stiffness in patients with hypercholesterolemia and preserved LV ejection fraction (LVEF), using newly developed ultrasonic strain imaging and carotid ultrasonography.

METHODS AND RESULTS

A total of 30 patients with hypercholesterolemia (>or=220 mg/dl for serum total cholesterol, and/or >or=140 mg/dl for LDL-C) were randomized to either administration of pitavastatin (1 or 2 mg/day; n=15) or no statin therapy (n=15) for 12 months. LV systolic and diastolic functions were evaluated by measuring transmitral flow velocity, mitral annular motion velocity, and the myocardial strain and strain rate profiles using pulsed Doppler, tissue velocity, and ultrasonic strain imaging. Subclinical atherosclerosis also was determined by measuring the intima - media thickness (IMT) and stiffness beta of the left and right common carotid arteries using B- and M-mode ultrasonography. During the follow-up period, the mean peak systolic strains of the LV posterior and inferior walls increased from 39.2+/-15.9% to 51.5+/-17.7% (p<0.01) and 46.0+/-12.2% to 57.5+/-10.3% (p<0.01), respectively, in the pitavastatin group compared with the no statin group. The mean peak early diastolic strain rates of the LV posterior and inferior walls also increased from -6.5+/-2.9 s(-1) to -9.5+/-2.8 s(-1) (p<0.01) and -6.5+/-2.5 s(-1) to -9.1+/-2.7 s(-1) (p<0.01), respectively, in the pitavastatin group. The stiffness beta decreased from 5.6+/-2.5 to 4.1+/-0.8 (p<0.05) in the pitavastatin group, whereas there was no significant change in IMT.

CONCLUSIONS

One year of pitavastatin treatment improved not only carotid arterial stiffness but also regional LV systolic and diastolic function in patients with hypercholesterolemia and preserved LVEF. Ultrasonic strain imaging has the potential to become a sensitive tool for detecting the effects of early medical intervention on latent regional LV myocardial dysfunction in this patient population.

Nonischemic heart failure in diabetes mellitus

PURPOSE OF REVIEW

Diabetic patients with heart failure have a poor prognosis. Although it has been demonstrated in animal models that metabolic maladaptation plays a pivotal role in contractile dysfunction of the heart, the understanding of 'diabetic cardiomyopathy' and its treatment in humans remains incomplete.

RECENT FINDINGS

Epidemiological studies show that structural changes in the left ventricle can be demonstrated before onset of clinical diabetes. Diastolic dysfunction is the earliest manifestation that is associated with increasing level of serum-free fatty acids and worsening glycemic control. Spectroscopic and histologic evidence in the human myocardium indicates a maladaptive metabolic response in diabetes, characterized by intramyocellular triglyceride accumulation. Studies also suggest a link between myocardial isoform switching, calcium homeostasis and altered metabolism in the development of heart failure. However, treatment directed at deranged metabolic control in diabetes is effective only in animals, and not in humans.

SUMMARY

Although clinical studies suggest the existence of 'diabetic cardiomyopathy', it is still difficult to prove causality. However, animal models and human studies suggest that systemic metabolic derangements may lead to metabolic, functional and structural maladaptation of the heart. The exact mechanisms of heart failure in diabetes remain elusive.

Type 1 diabetes, hyperglycaemia, and the heart

Type 1 diabetes is associated with a substantially increased risk of cardiovascular disease that might not always be appreciated in view of the fairly young age of patients with this condition. In fact, in type 1 diabetes, the heart is subject to a variety of pathological insults, including accelerated atherosclerosis, cardiac autonomic neuropathy, and possibly intrinsic cardiomyopathy. Although the relation between hyperglycaemia and microvascular complications has been well established, a direct effect of hyperglycaemia on cardiovascular disease in type 1 diabetes has long been debated. More recently, several studies, most notably the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications, have clarified this issue and provided conclusive evidence that hyperglycaemia is indeed a mediator of cardiovascular risk in type 1 diabetes and that intensive diabetes therapy can reduce cardiovascular disease outcomes. We review current concepts in type 1 diabetes and the heart, focusing on recent insights into the central role of hyperglycaemia.

Uncomplicated type 1 diabetes and preclinical left ventricular myocardial dysfunction: insights from echocardiography and exercise cardiac performance evaluation

OBJECTIVES

Left ventricular (LV) diastolic dysfunction is considered the earliest manifestation of diabetic cardiomyopathy. Whether LV abnormalities identified at rest by echocardiography predict peak exercise LV performance in uncomplicated type 1 diabetes mellitus (DM1) is largely unknown.

RESEARCH DESIGN AND METHODS

We evaluated LV size, mass, and functions and peak exercise LV performance in 25 subjects with uncomplicated DM1 (median disease duration 13.5 years, 1-30 years) and in 56 non-DM subjects (24 hypertensive (HT) and 32 normotensive (NT)). Overt coronary heart disease, significant microangiopathy and central autonomic neuropathy were minimized by exclusion criteria. Peak exercise LV stroke index (SVi), cardiac index (COi), LV ejection fraction (EF), LV end-diastolic and end-systolic volumes were assessed noninvasively. No subject was on cardiovascular medications at the time of evaluation.

RESULTS

In our study, DM1 did not show LV hypertrophy or impaired LV systolic function at rest. Prevalence of diastolic dysfunction was 8% among DM1, 18% among NT and 50% among HT. Pre-exercise heart rate, SVi, COi, and peak exercise blood pressure (BP) and heart rate were comparable among the three groups, but peak exercise LV EF, SVi and COi were lower in DM1 than in HT and NT independent to covariates (p<0.05). In separate analyses, DM1 predicted lower peak exercise SVi (B=-6.2) and COi (B=-1.6, both p<0.05) independently. Within DM1, glycated haemoglobin (HbA1c) and disease duration did not predict peak exercise LV systolic function.

CONCLUSIONS

Our study suggests that uncomplicated DM1 may be associated with subnormal LV contractility reserve, which might not be predicted by LV dysfunction evaluated at rest.

LV systolic impairment in patients with asymptomatic coronary heart disease and type 1 diabetes is related to coronary atherosclerosis, glycaemic control and advanced glycation endproducts

AIMS

To evaluate whether heart failure in type 1 diabetes is linked to poor glycaemic control, coronary atherosclerosis or advanced glycation endproducts (AGEs).

METHODS

Twenty six patients with type 1 diabetes (mean duration 32+/-5 years), and 16 age matched controls were recruited. Mean HbA(1c) through 18 years (HbA(1c)18), serum levels of AGEs and coronary atherosclerotic burden (CAB) were determined by IVUS. Peak tissue velocities and strain by tissue Doppler imaging were measured in 12 LV regions as an evaluation of LV function.

RESULTS

Systolic tissue velocity was inversely correlated to CAB (r=0.53, p<0.01), to HbA(1c)18 (r=0.46, p<0.05) and to the duration of diabetes (r=0.46, p<0.05). Systolic strain was inversely correlated to HbA(1c)18 (r=0.45, p<0.05), to duration of diabetes (r=0.41, p<0.05), and tended to correlate with AGEs (r=0.37, p=0.07). In multiple regression analyses, CAB and HbA(1c)18 were significant independent predictors for systolic velocity, while AGEs and duration of diabetes were significant predictors of systolic strain.

CONCLUSION

LV systolic function was impaired by increasing coronary atherosclerosis and worsening of glycaemic control. AGEs might be another mechanism for the increased risk of heart failure in type 1 diabetes.

No evidence for left ventricular diastolic dysfunction in asymptomatic normotensive type 2 diabetic patients: a case-control study with new echocardiographic techniques

OBJECTIVE

We sought to determine whether abnormalities of left ventricular structure and function could be detected in asymptomatic type 2 diabetic patients free of cardiovascular complications.

RESEARCH DESIGN AND METHODS

We compared 48 subjects with type 2 diabetes (34 men, 50+/-6 years) without hypertension, coronary artery disease and microangiopathic complications with 30 age-matched healthy controls. Left ventricular diastolic function was assessed by conventional Doppler echocardiography and new echocardiographic techniques (tissue Doppler imaging, color M-mode propagation velocity). A pseudonormal (PN) pattern of left ventricular filling was screened by several methods including Valsalva maneuver.

RESULTS

Systolic function was normal in all patients. There was no significant difference in conventional and new echocardiographic Doppler indices of diastolic function between patients and control subjects. A PN diastolic function frequently suggested by the Valsalva maneuver (20 patients) was excluded using the new parameters.

CONCLUSIONS

Diastolic dysfunction is not as frequent as previously described in selected patients with type 2 diabetes free of microangiopathic complications. New Doppler echocardiographic methods provide, in contrast with the Valsalva maneuver, a reliable estimate of diastolic function and should be incorporated in the non-invasive screening for diabetic cardiomyopathy.

Causes and characteristics of diabetic cardiomyopathy

Type 1 and type 2 diabetic patients are at increased risk of cardiomyopathy and heart failure is a major cause of death for these patients. Cardiomyopathy in diabetes is associated with a cluster of features including decreased diastolic compliance, interstitial fibrosis and myocyte hypertrophy. The mechanisms leading to diabetic cardiomyopathy remain uncertain. Diabetes is associated with most known risk factors for cardiac failure seen in the overall population, including obesity, dyslipidemia, thrombosis, infarction, hypertension, activation of multiple hormone and cytokine systems, autonomic neuropathy, endothelial dysfunction and coronary artery disease. In light of these common contributing pathologies it remains uncertain whether diabetic cardiomyopathy is a distinct disease. It is also uncertain which factors are most important to the overall incidence of heart failure in diabetic patients. This review focuses on factors that can have direct effects on diabetic cardiomyocytes: hyperglycemia, altered fuel use, and changes in the activity of insulin and angiotensin. Particular attention is given to the changes these factors can have on cardiac mitochondria and the role of reactive oxygen species in mediating injury to cardiomyocytes.

Diastolic dysfunction and diabetic cardiomyopathy: evaluation by Doppler echocardiography

Doppler echocardiography has largely contributed to show the existence of a distinct diabetic cardiomyopathy. Several studies have pointed out the evidence of left ventricular (LV) remodeling and hypertrophy in alterations of both midwall systolic mechanics and LV diastolic filling in diabetes mellitus (DM), independent of the coexistence of concomitant risk factors. Further progress will be provided by new ultrasound technologies in this clinical setting. The combination of pulsed tissue Doppler study of mitral annulus with transmitral inflow may be clinically valuable for obtaining information about left ventricular filling pressure (LVFP) and unmasking Doppler inflow pseudonormal pattern, a hinge point for the progression toward advanced heart failure. In the absence of epicardial coronary artery stenosis, the ultrasound assessment of coronary flow reserve (CFR) may identify the dysfunction of coronary microcirculation, in relation with glycemic levels, insulin resistance, sympathetic overdrive, endothelial dysfunction, abnormalities of the angiotensin-renin system, and LV remodeling/hypertrophy. Diastolic dysfunction and impairment of CFR may be associated in DM, with a likely common origin. In this view, a comprehensive transthoracic Doppler evaluation of diabetic patients should include the assessment of diastolic function and estimation of LVFP by tissue Doppler, and coronary microvascular function by CFR test. Additional analysis of regional wall motion during a stress test would be required in patients with suspected coronary artery disease, another cause of diastolic dysfunction.

Alterations in left ventricular structure and function in type-1 diabetics: a focus on left atrial contribution to function

This study was designed to determine the effects of type 1 diabetes mellitus (T1DM) on left ventricular (LV) and particularly left atrial (LA) structure and function. We evaluated 88 non-obese subjects: 44 with T1DM, 44 age- and gender-matched normal controls (age 39 +/- 11 years). LV and LA structure and function were quantified using two-dimensional echocardiography, pulse-wave Doppler, and tissue Doppler imaging, including early and late diastolic myocardial velocities (Em global and Am global, respectively). The T1DM subjects averaged higher heart rate, relative wall thickness, and ejection fraction, and lower indexed end-systolic volume than normal controls (P < .001, P < .05, P = .01, and P < .05, respectively). T1DM was related to A wave velocity, Am global, A wave integral, LA ejection fraction, and LA systolic ejection fraction (P < .01, P < .05, P < .0005, P < .001, and P < .0005, respectively). In multivariate analyses, T1DM was an independent predictor of the A wave integral, LA ejection fraction, and LA systolic ejection fraction (P < .01, P < .01, and P < .005, respectively). Thus, despite increased relative wall thickness, LV systolic function is increased and early diastolic filling is normal in T1DM subjects; however, they possess changes in LA transport function suggesting increased reliance on LA contribution to LV filling.

Plasma triglyceride level is an independent predictor of altered left ventricular relaxation

BACKGROUND

Diastolic dysfunction, manifested by impaired left ventricular (LV) relaxation, is prevalent among individuals with metabolic disorders. The objective of this study was to evaluate the extent to which plasma triglyceride (TG) levels are related to LV diastolic function.

METHODS

A total of 424 subjects (age 49 +/- 12 years) had fasting plasma TG levels measured and underwent echocardiography for assessment of LV structure and function: LV ejection fraction and LV mass indexed to height (LVM/Ht(2.7)); transmitral inflow early diastolic peak velocity (E wave) and late diastolic peak velocity (A wave), and E wave to A wave ratio (E/A); deceleration time; and Doppler tissue imaging early diastolic myocardial velocity (EM), an index of LV relaxation.

RESULTS

All subjects had normal LV ejection fraction, 48% had hypertension, 16% had increased LVM/Ht(2.7), 11% had type 2 diabetes mellitus, 37% were obese, and 27% had hypertriglyceridemia (TG > 150 mg/dL). Univariate analysis showed significant relationships between TG level and E/A, deceleration time, and Em (P < or = .001 for all). After adjustment for potential confounders in multivariate models (eg, age, systolic blood pressure, and LVM/Ht(2.7)), TG levels remained predictive of E/A, deceleration time, and Em (P < or = .05, <.001, and < or =.0001, respectively). Stepwise multivariate analysis showed that after age and body mass index, the TG level was the next most predictive variable of Em.

CONCLUSIONS

Plasma TG levels show a strong relationship with impaired LV relaxation, an early marker of diastolic dysfunction in human beings. These findings support a hypothesis whereby elevated TG levels favor myocyte intracellular lipid accumulation, possibly leading to lipotoxic diastolic dysfunction.

Effect of glycemic control on left ventricular diastolic function in type 1 diabetes mellitus

Left ventricular (LV) diastolic dysfunction is a main feature of diabetic heart disease. The aim of this prospective study was to evaluate the influence of glycemic control on diastolic function in type 1 diabetes mellitus. Thirty-six normotensive (24-hour blood pressure <130/80 mm Hg) subjects with inadequately controlled (glycated hemoglobin >7%) type 1 diabetes, without clinically detectable heart disease, were enrolled. After the basal evaluation, insulin therapy was modified to improve glycemic control. Glycated hemoglobin, LV echocardiography, 24-hour blood pressure monitoring, and laboratory tests were repeated after 6 months in all patients and after 12 months in 27 patients. At the basal evaluation, LV anatomy and systolic function were normal in all, and diastolic function was impaired in 14 patients. After 6 months, the mean values of body mass index, 24-hour blood pressure, and LV anatomy and systolic function were unchanged; mean glycated hemoglobin was decreased (p < 0.001), and mean values of diastolic parameters were significantly improved. After 12 months, the mean values of all blood pressure, metabolic, and LV parameters were unchanged. Percent changes of diastolic parameters were inversely correlated with percent changes of glycated hemoglobin, considering changes from the basal to the 6-month evaluation, as well as changes from the 6- to the 12-month evaluation. In conclusion, in normotensive patients with type 1 diabetes, a close relation was found between glycemic control and LV diastolic function, which improves when glycemic control improves. Therefore, diastolic dysfunction can be prevented or reversed, at least partly, by tight glycemic control.

Heart Failure and Nephropathy: Catastrophic and Interrelated Complications of Diabetes

Heart failure (HF) is a major contributor to poor quality of life, a leading cause of hospitalization, and cause of premature death. Both kidney disease and diabetes are major and independent risk factors for the development of heart failure, such that individuals with diabetic nephropathy are at especially high risk. Such patients not only are likely to have coronary artery disease and hypertension but also are likely to have diabetic cardiomyopathy, a distinct pathologic entity that is more closely associated with the microvascular than the macrovascular complications of diabetes. In addition to a better understanding of the epidemiology of HF, advances in noninvasive imaging have highlighted the importance of early cardiac dysfunction in diabetes and the high prevalence of HF with preserved left ventricular systolic function. Although significant renal dysfunction is usually an exclusion criterion in HF trials, diabetes is often a prespecified subgroup so that subanalyses of large multicenter clinical trials do provide some guidance in therapeutic decision-making. However, further therapies for both HF and nephropathy in diabetes clearly are needed, and a number of new therapeutic strategies that target both disorders have already entered the clinical arena.

Coronary atherosclerosis in diabetic subjects: clinical significance, anatomic characteristics, and identification with in vivo imaging

Diabetes mellitus is an endocrine disorder that promotes the development and progression of atherosclerotic coronary disease. As a consequence, cardiovascular disease is the most important cause of morbidity and mortality in diabetics. Early identification and treatment of asymptomatic stages provides the opportunity to prevent cardiovascular end organ complications. Modem clinical imaging modalities allow the assessment of early atherosclerotic changes in coronary arteries; however, prospective evidence that atherosclerosis imaging impacts on clinical outcome is not yet available and future studies are necessary.

Female children and adolescents with type 1 diabetes have more pronounced early echocardiographic signs of diabetic cardiomyopathy

OBJECTIVE

This study was designed to assess whether children and adolescents with type 1 diabetes have early echocardiographic signs of subclinical cardiac dysfunction and whether sex, state of metabolic control, and diabetes duration are of influence.

RESEARCH DESIGN AND METHODS

Systolic and diastolic blood pressure in supine and upright positions and echocardiographic parameters, including tissue Doppler measurements of the septal mitral annulus, were evaluated in 80 children and adolescents with stable type 1 diabetes and 52 age- and sex-matched control subjects. A possible correlation was examined for age, sex, HbA(1c), and diabetes duration with univariate and multivariate regression analysis.

RESULTS

Female diabetic patients showed significantly larger left ventricular wall dimensions (left ventricular posterior wall in diastole 0.54 +/- 0.08 vs. 0.48 +/- 0.11 cm) and signs of significant diastolic filling abnormalities on conventional and tissue Doppler echocardiography (mitral valve-atrial contraction velocity 0.47 +/- 0.12 vs. 0.40 +/- 0.09 m/s; tricuspid valve-atrial contraction velocity 0.35 +/- 0.09 vs. 0.30 +/- 0.07 m/s; early filling velocity/myocardial velocity during early filling 7.15 +/- 1.47 vs. 6.17 +/- 1.07; isovolumetric relaxation time [IVRT] 66 +/- 8 vs. 58 +/- 8 ms) compared with female control subjects, suggesting delayed myocardial relaxation. Male diabetic patients only differed significantly from their control subjects for IVRT (66 +/- 9 vs. 59 +/- 8 ms). The measured parameters showed an expected correlation with age and BMI standard deviation scores in the control group. This correlation was significantly weaker in the diabetic population; only a weak influence was found for diabetes duration and glycosylated hemoglobin levels.

CONCLUSIONS

Young diabetic patients already have significant changes in left ventricular dimensions and myocardial relaxation, with the girls clearly being more affected. Tissue Doppler proved to have additional value in the evaluation of ventricular filling in this population. Almost no correlation was found for diabetes duration and HbA(1c) with the cardiovascular changes.