Heart disease in diabetic patients

Phenome-wide association network demonstrates close connection with individual disease trajectories from the HUNT study

Disease networks offer a potential road map of connections between diseases. Several studies have created disease networks where diseases are connected either based on shared genes or Single Nucleotide Polymorphism (SNP) associations. However, it is still unclear to which degree SNP-based networks map to empirical, co-observed diseases within a different, general, adult study population spanning over a long time period. We created a SNP-based phenome-wide association network (PheNet) from a large population using the UK biobank phenome-wide association studies. Importantly, the SNP-associations are unbiased towards much studied diseases, adjusted for linkage disequilibrium, case/control imbalances, as well as relatedness. We map the PheNet to significantly co-occurring diseases in the Norwegian HUNT study population, and further, identify consecutively occurring diseases with significant ordering in occurrence, independent of age and gender in the PheNet. Our analysis reveals an overlap far larger than expected by chance between the two disease networks, with diseases typically connecting within their own category. Upon examining the sequential occurrence of diseases in the HUNT dataset, we find a giant component consisting of mostly cardiovascular disorders. This allows us to identify sequentially occurring diseases that are genetically linked and co-occur frequently, while also highlighting non-sequential diseases. Furthermore, we observe that survivors of severe cardiovascular diseases subsequently often face less severe conditions, but with a reduced time until their next fatal illness. The HUNT sub-PheNet showing both genetically and co-observed diseases offers an interesting framework to study groups of diseases and examine if they, in fact, are comorbidities. We find that the HUNT sub-PheNet offers the possibility to pinpoint exactly which mutation(s) constitute shared cause of the diseases. This could be of great benefit to both researchers and clinicians studying relationships between diseases.

SGLT-2 Inhibitors: The Next-generation Treatment for Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) has become a worldwide concern in recent years, primarily in highly developed Western societies. T2DM causes systemic complications, such as atherosclerotic heart disease, ischemic stroke, peripheral artery disease, kidney failure, and diabetes-related maculopathy and retinopathy. The growing number of T2DM patients and the treatment of long-term T2DM-related complications pressurize and exhaust public healthcare systems. As a result, strategies for combating T2DM and developing novel drugs are critical global public health requirements. Aside from preventive measures, which are still the most effective way to prevent T2DM, novel and highly effective therapies are emerging. In the spotlight of next-generation T2DM treatment, sodium-glucose co-transporter 2 (SGLT-2) inhibitors are promoted as the most efficient perspective therapy. SGLT-2 inhibitors (SGLT2i) include phlorizin derivatives, such as canagliflozin, dapagliflozin, empagliflozin, and ertugliflozin. SGLT-2, along with SGLT-1, is a member of the SGLT family of proteins that play a role in glucose absorption via active transport mediated by Na+/K+ ATPase. SGLT-2 is only found in the kidney, specifically the proximal tubule, and is responsible for more than 90% glucose absorption. Inhibition of SGLT-2 reduces glucose absorption, and consequently increases urinary glucose excretion, decreasing blood glucose levels. Thus, the inhibition of SGLT-2 activity ultimately alleviates T2DM-related symptoms and prevents or delays systemic T2DM-associated chronic complications. This review aimed to provide a more detailed understanding of the effects of SGLT2i responsible for the acute improvement in blood glucose regulation, a prerequisite for T2DM-associated cardiovascular complications control.

Strong independent association between third-degree AV-block and diabetes mellitus using a large database

BACKGROUND

Recent data suggests an association between DM and third-degree AV- Block. The goal of this study was to evaluate the independent association between diabetes and third-degree AV-Block using a very large database.

METHOD

We used ICD-9 Codes for DM and third-degree AV-block from the Nationwide Inpatient Sample (NIS) database. We randomly selected the 1992 and 2002 databases which are 10 years apart as two independent samples. We used uni- and multi-variate analysis to evaluate this association.

RESULTS

1992 database contained a total of 6,195,744 patients. Diabetes occurred in (0.5 %) of patients with third-degree AV-block vs. (0.2 %) of the control (OR: 2.15, CI 2.06-2.25, p < 0.0001). 2002 database contained a total of 7,853,982 patients. Diabetes occurred in (0.4 %) of patients with third-degree AV-block vs. (0.2 %) of the control (OR: 1.86, CI: 1.80-1.93, p < 0.0001). Using Multivariate analysis adjusting for age, congestive heart failure, and coronary artery disease, DM remained independently associated with third-degree AV block in both databases. (for 1999: OR: 2.54, CI 2.51-2.57, p < 0.0001 and for 2002 OR: 1.56, CI 1.55-1.57, p < 0.0001).

CONCLUSION

DM is independently associated with third-degree AV-block with persistent association over a period of 10 years. The cause of this association warrants further investigation.

Research progress on the relationship between autophagy and chronic complications of diabetes

Diabetes is a common metabolic disease whose hyperglycemic state can induce diverse complications and even threaten human health and life security. Currently, the treatment of diabetes is restricted to drugs that regulate blood glucose and have certain accompanying side effects. Autophagy, a research hotspot, has been proven to be involved in the occurrence and progression of the chronic complications of diabetes. Autophagy, as an essential organismal defense mechanism, refers to the wrapping of cytoplasmic proteins, broken organelles or pathogens by vesicles, which are then degraded by lysosomes to maintain the stability of the intracellular environment. Here, we review the relevant aspects of autophagy and the molecular mechanisms of autophagy in diabetic chronic complications, and further analyze the impact of improving autophagy on diabetic chronic complications, which will contribute to a new direction for further prevention and treatment of diabetic chronic complications.

Metformin alleviates monoamine oxidase-related vascular oxidative stress and endothelial dysfunction in rats with diet-induced obesity

In the past decade, monoamine oxidase (MAO) with 2 isoforms, MAO-A and B, has emerged as an important source of mitochondrial reactive oxygen species (ROS) in cardio-metabolic pathologies. We have previously reported that MAO-related oxidative stress mediates endothelial dysfunction in rodent models of diabetes and diabetic patients; however, the role of MAO in the vascular impairment associated to obesity has not been investigated so far. Metformin (METF), the first-line drug in the therapy of type 2 diabetes mellitus, has been reported to elicit vasculoprotective effects via partially elucidated mechanisms. The present study was purported to assess the effects of METF on MAO expression, ROS production and vasomotor function of aortas isolated from rats with diet-induced obesity. After 24 weeks of high calorie junk food (HCJF) diet, isolated aortic rings were prepared and treated with METF (10 μM, 12 h incubation). Measurements of MAO expression (quantitative PCR and immune histochemistry), ROS production (spectrometry and immune-fluorescence) and vascular reactivity (myograph studies) were performed in rat aortic rings. MAO expression was upregulated in aortic rings isolated from obese rats together with an increase in ROS production and an impairment of vascular reactivity. METF decreased MAO expression and ROS generation, reduced vascular contractility and improved the endothelium-dependent relaxation in the diseased vascular preparations. In conclusion, METF elicited vascular protective effects via the mitigation of MAO-related oxidative stress in the rat model of diet-induced obesity.

Chest pain symptoms differences between diabetes mellitus and non-diabetes mellitus patients with acute coronary syndrome: A pilot study

BACKGROUND

Chest pain is considered one of the crucial indicators in detecting acute coronary syndrome (ACS), and one of the most common complaints frequently found in hospitals. Atypical characteristics of chest pain have prevented patients from being aware of ACS. Chest pain symptoms have become ambiguous, particularly for specific parameters, such as gender, diabetes mellitus (DM), or other clinical conditions. Therefore, it is critical for high-risk patients to have adequate knowledge of specific symptoms of ACS, which is frequently associated with late treatment or prehospital delay. Therefore, this study aims to identify the particular characteristics of chest pain symptoms in DM and non-DM patients with ACS.

DESIGN AND METHODS

This is a quantitative and non-experimental research, with the cross-sectional approach used to carry out the analytical observation at a general hospital from January-April 2019. Data were obtained from a total sample of 61 patients, comprising 33 ACS with DM and 28 ACS non-DM patients.

RESULTS

The result showed that the characteristic of patients with chest pain symptoms has a significant relation to DM and ACS. Therefore, non-DM patients with ACS are more likely to feel chest pain at moderate to a severe level, while ACS-DM patients are more likely to have low to moderate chest pain levels.

CONCLUSION

The significant differences in the characteristics of chest pain in DM and non-DM patients suffering from acute coronary syndrome are the points of location of chest pain radiating to the neck and quality of pain.

MORPHOLOGICAL AND FUNCTIONAL MYOCARDIAL ABNORMALITIES IN THE CHORNOBYL NPP ACCIDENT CLEAN-UP WORKERS OF «IODINE» PERIOD HAVING GOT TYPE 2 DIABETES MELLITUS

OBJECTIVE

Evaluation of morphological and functional myocardial abnormalities in the Chornobyl NPP (ChNPP)accident clean-up workers (ACUW) of the «iodine» period exposed to ionizing radiation at a young age and havinggot the type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

The ChNPP ACUW of «iodine» period (n=111) exposed to ionizing radiation (IR) at a young age(18-35 years) were involved in the study. Subjects having got the T2DM were included in study Group I (n = 66), per-sons with normal glucose challenge test were selected as a comparison Group II (n = 45). External radiation doses (ERD)ranged from 10 to 860 mSv. The Group III (clinical control) included persons having got the T2DM with no radiationexposure in a history (n=20). Group IV was the normative one. There was no statistical difference between the groups inage, sociodemographic characteristics and level of education. Echocardiography and cardiac Doppler sonography wereperformed in one- and two-dimensional regimens according to the recommendations of the European Association ofEchocardiography. Total adiponectin and proinflammatory cytokine (TNF-α and IL-6) concentrations were assayed by theimmunoenzyme method. Statistical processing of data was carried out using the Microsoft® Exel 2002 software.

RESULTS

Myocardial remodeling in the ChNPP ACUW of a «iodine» period having the T2DM occurred through a sig-nificant increase of its linear parameters. Volumetric parameters (EDV, ESV and their indexes) were within maximumpermissible limits significantly exceeding however the values in the Group IV. There was aт increase in myocardialmass of the left ventricle and its indices with the formation of structural-geometric abnormalities, mainly in theform of concentric hypertrophy with a decrease in the myocardial contractile capacity. There was no differences ofthe vast majority of key morphometric parameters of myocardium in the dose subgroups, while in persons with ERD> 500 mSv the incidence of serious left ventricular hypertrophy (LVMMI > 149 g/m2) significantly exceeded thisvalue in individuals with lower ERD. At a maximum ERD the more intense fibroplastic processes were observed inmyocardium [a significant increase in the interstitial collagen volumetric fraction (ICVF)] as compared to the caseswith ERD up to 50 mSv. Intensification of myocardial fibroblastic processes occurred in the comparizin group andgroup off clinical control. In combination with concentric myocardial hypertrophy this may lead to an increased riskof cardiovascular complications. Strong negative correlation was revealed between the parameters of left ventricu-lar structure in diastole and adiponectin level in the ChNPP ACUW of a «iodine» period with diagnosed T2DM, high-lighting its cardioprotective effect. At the same time, the content of FNP-α and IL-6 proinflammatory cytokines hada positive correlation with the main parameters of abnormal myocardial remodeling, indicating the possibility oftheir role in unfavorable cardiovascular modifications.

CONCLUSIONS

The decreased adiponectin level and elevated levels of TNF-α and IL-6 in the ChNPP ACUW of a«iodine» period having got the T2DM are the meaningful factors in progression of LV geometric remodeling. Togetherwith fibroplastic processes (a significant increase in ICVF) this may be a basis for the development of myocardialremodeling processes, namely a concentric hypertrophy, which is a prerequisite for the development of complica-tions in cardiovascular system.

Aerobic exercise can modulate the underlying mechanisms involved in the development of diabetic complications

Diabetes mellitus is a highly prevalent metabolic disorder that affects many molecular pathways, causing a shift from a physiologic to a pathophysiologic state. Alterations in the molecular pathways promote diabetic complications and, thus, many medical and nonmedical therapies have been directed at preventing these complications. Despite the beneficial effects on moderating glycemic control, medical therapies may also have unfavorable side effects. This makes nonmedical therapeutic approaches more attractive due to lower pharmacological side effects of these strategies compared to medical agents. Aerobic exercise is now considered as a major nonmedical strategy that can promote beneficial and protective effects to counteract the development of diabetic complications via attenuation of the major molecular mechanisms involved in diabetes.

The Chinese Herb Yi-Qi-Huo-Xue Protects Cardiomyocyte Function in Diabetic Cardiomyopathy

Aims. To study the effect of the Chinese herb Yi-qi-huo-xue on cardiomyopathy in diabetic rats. Methods. Rats were fed a high fat and high glucose diet and injected with 50 ml/kg streptozotocin (STZ) to induce diabetic cardiomyopathy (DCM), followed by treatment with Yi-qi-huo-xue for 4 weeks. We measured the rats' heart weight index, observed the myocardial morphology using hematoxylin eosin (HE) staining, and determined the content of collagen types I and III in the myocardium using enzyme-linked immunosorbent assay (ELISA). We determined Bcl-2, Bax, and P53 protein expression by Western blot analysis and the cardiomyocyte apoptosis rate via a flow cytometry assay. Results. Compared with the rats in the control group, the diabetic rats gained weight and had increased blood sugar levels, an enhanced heart weight index, and increased myocardial pathophysiological damage. There was a decrease in their Bcl-2 expression, and their Bax and P53 expression increased. The Bcl-2/Bax ratio was enhanced, and there was an increase in the content of collagen types I and III in the myocardium. After treatment with Yi-qi-huo-xue, all levels listed above returned to normal. Conclusion. The Chinese herb Yi-qi-huo-xue degraded the myocardial interstitial collagen types I and III to protect the myocardium of the diabetic rats, thus delaying the role of myocardial fibrosis. Yi-qi-huo-xue could play an important role in protecting the myocardium of DCM rats by enhancing the expression of the Bcl-2 protein, inhibiting the expression of the Bax and P53 proteins, increasing the ratio of Bcl-2/Bax, and inhibiting the apoptosis of cardiomyocytes.

Effect of hepatic insulin expression on lipid metabolism in diabetic mice

BACKGROUND

Hypertriglyceridemia is a common lipid disorder that is characterized by elevated plasma levels of triglyceride (TG)-rich particles, such as very low-density lipoprotein (VLDL), in poorly controlled diabetes. The aim of the present study was to determine the potential therapeutic effect of hepatic insulin production on hypertriglyceridemia in mice.

METHODS

Mice were induced diabetic and hypertriglyceridemic by streptozotocin (STZ) treatment. Using an adenovirus-mediated gene transfer approach, we delivered rat preproinsulin cDNA into the liver of diabetic mice and then determined plasma TG metabolism. To investigate the mechanism by which hepatic insulin improves TG metabolism, we determined hepatic expression of apolipoprotein C-III (ApoC-III), a structural moiety and functional inhibitor of VLDL-TG catabolism.

RESULTS

Plasma VLDL-TG levels were markedly elevated in STZ-treated mice, and were accompanied by hyperglycemia and hypertriglyceridemia. These metabolic abnormalities were restored to near normal following hepatic insulin production in insulin vector-treated diabetic mice. In contrast, hypertriglyceridemia and hyperglycemia persisted in control vector-treated diabetic animals. Hepatic ApoC-III expression became deregulated secondary to insulin deficiency, contributing to impaired TG metabolism in diabetic mice. Hepatic insulin production suppressed excessive hepatic ApoC-III production to basal levels.

CONCLUSION

Hepatic insulin production is efficacious in correcting hypertriglyceridemia associated with insulin deficiency in diabetic mice.

Cost-effectiveness of screening strategies to detect heart failure in patients with type 2 diabetes

BACKGROUND

Heart failure (HF), especially with preserved ejection fraction (HFpEF) is common in older patients with type 2 diabetes (T2DM), but often not recognized. Early HF detection in older T2DM patients may be worthwhile because treatment may be initiated in an early stage, with clear beneficial treatment in those with reduced ejection fraction (HFrEF), but without clear prognostic beneficial treatment in those with HFpEF. Because both types of HF may be uncovered in older T2DM, screening may improve health outcomes at acceptable costs. We assessed the cost-effectiveness of five screening strategies in patients with T2DM aged 60 years or over.

METHODS

We built a Markov model with a lifetime horizon based on the prognostic results from our screening study of 581 patients with T2DM, extended with evidence from literature. Cost-effectiveness was calculated from a Dutch healthcare perspective as additional costs (Euros) per additional quality-adjusted life-year (QALY) gained. We performed probabilistic sensitivity analysis to assess robustness of these outcomes. Scenario analyses were performed to assess the influence of the availability of effective treatment of heart failure with preserved ejection fraction.

RESULTS

For willingness to pay values in the range of €6050/QALY-€31,000/QALY for men and €6300/QALY-€42,000/QALY for women, screening-based checking the electronic medical record for patient characteristics and medical history plus the assessment of symptoms had the highest probability of being cost-effective. For higher willingness-to-pay values, direct echocardiography was the preferred screening strategy. Cost-effectiveness of all screening strategies improved with the increase in effectiveness of treatment for HFpEF.

CONCLUSIONS

Screening for HF in older community-dwelling patients with T2DM is cost-effective at the commonly used willingness-to-pay threshold of €20.000/QALY by checking the electronic medical record for patient characteristics and medical history plus the assessment of symptoms. The simplicity of such a strategy makes it feasible for implementation in existing primary care diabetes management programs.

Non-haemodynamic anti-anginal agents in the management of patients with stable coronary artery disease and diabetes: A review of the evidence

Patients with coronary artery disease and concomitant diabetes mellitus tend to have more extensive vessel disease than non-diabetes mellitus coronary artery disease patients, are at high risk of adverse cardiovascular events and suffer from a great anginal burden. Very few trials have specifically addressed the issue of optimal anti-anginal therapy in coronary artery disease patients who also have diabetes mellitus. Among 'classical' anti-anginal agents, recent guidelines do not specifically recommend any molecule over others; however, European Society of Cardiology guidelines acknowledge that favourable data in patients with concomitant diabetes mellitus and coronary artery disease are available for trimetazidine and ranolazine, two anti-anginal agents with a non-haemodynamic mechanism of action. The aim of this article is to review available evidence supporting the anti-anginal efficacy of these two drugs in the difficult-to-treat population of diabetes mellitus patients, including their effects on glycated haemoglobin (HbA1c), a measure of medium-term glycaemic control. Although direct head-to-head comparisons have not been performed, available evidence favours ranolazine as an effective anti-anginal agent over trimetazidine in this population. In addition, ranolazine lowers HbA1c, indicating that it may improve glycaemic control in patients with diabetes mellitus. Conversely, scanty data are available on the metabolic effects of trimetazidine in this cohort of patients. Thus, ranolazine may represent a valuable therapeutic option in stable coronary artery disease patients with diabetes mellitus.

Subclinical Detection of Diabetic Cardiomyopathy with MicroRNAs: Challenges and Perspectives

The prevalence of cardiac diabetic diseases has been increased around the world, being the most common cause of death and disability among diabetic patients. In particular, diabetic cardiomyopathy is characterized with a diastolic dysfunction and cardiac remodelling without signs of hypertension and coronary artery diseases. In an early stage, it is an asymptomatic disease; however, clinical studies demonstrate that diabetic myocardia are more vulnerable to injury derived by acute myocardial infarct and are the worst prognosis for rehabilitation. Currently, biochemical and imaging diagnostic methods are unable to detect subclinical manifestation of the disease (prior to diastolic dysfunction). In this review, we elaborately discuss the current scientific evidences to propose circulating microRNAs as promising biomarkers for early detection of diabetic cardiomyopathy and, then, to identify patients at high risk of diabetic cardiomyopathy development. Moreover, here we summarise the research strategies to identify miRNAs as potential biomarkers, present limitations, challenges, and future perspectives.

Possible relationship between the heart rates and serum amyloid A in a hyperglycemic population

Hyperglycemia predicts cardiovascular disease (CVD)-related outcomes. The resting heart rates (HRs) and serum amyloid A (SAA), an inflammatory marker, are respectively factors associated with CVD-related outcomes; however, little is known regarding the associations between these two factors. This study aimed to investigate the correlation between the HRs and SAA levels under hyperglycemic conditions. This study included 298 subjects (males, 44%; mean age, 61.1 years) without a history of CVD and/or hypertensive levels. Clinical data, including general laboratory measurements, HRs and SAA, were measured. The analyses were performed after dividing all of the subjects into two groups based on the blood glucose level (< or ≥ 6.1 mmol/L). There was a higher SAA level in the hyperglycemic group (n = 143; median [interquartile range] 6.1 [4.1-10.6] μg/mL) than in the counterpart group (n = 155; 6.0 [3.5-8.5] μg/mL; p < 0.01). There was a trend toward increased HRs in the hyperglycemic group (mean [standard deviation] 65.3 [11.2] bpm) compared to the counterpart group (63.2 [9.4] bpm; p = 0.08). In the hyperglycemic group, there was a significant positive correlation between the HRs and SAA levels (multiple variables-adjusted analysis: β = 0.21, p = 0.02), while no correlation was found in the counterpart group (β = 0.06, p = 0.50). In summary, a positive correlation between the HRs and SAA levels can present under hyperglycemic conditions. These findings may provide relevant insights into the CVD-related pathologies associated with hyperglycemia. Further studies are warranted.

Equilibrative Nucleoside Transporters 1 and 4: Which One Is a Better Target for Cardioprotection Against Ischemia-Reperfusion Injury?

The cardioprotective effects of adenosine and adenosine receptor agonists have been studied extensively. However, their therapeutic outcomes in ischemic heart disease are limited by systemic side effects such as hypotension, bradycardia, and sedation. Equilibrative nucleoside transporter (ENT) inhibitors may be an alternative. By reducing the uptake of extracellular adenosine, ENT1 inhibitors potentiate the cardioprotective effect of endogenous adenosine. They have fewer systemic side effects because they selectively increase the extracellular adenosine levels in ischemic tissues undergoing accelerated adenosine formation. Nonetheless, long-term inhibition of ENT1 may adversely affect tissues that have low capacity for de novo nucleotide biosynthesis. ENT1 inhibitors may also affect the cellular transport, and hence the efficacy, of anticancer and antiviral nucleoside analogs used in chemotherapy. It has been proposed that ENT4 may also contribute to the regulation of extracellular adenosine in the heart, especially under the acidotic conditions associated with ischemia. Like ENT1 inhibitors, ENT4 inhibitors should work specifically on ischemic tissues. Theoretically, ENT4 inhibitors do not affect tissues that rely on ENT1 for de novo nucleotide synthesis. They also have no interaction with anticancer and antiviral nucleosides. Development of specific ENT4 inhibitors may open a new avenue in research on ischemic heart disease therapy.

Impact of diabetes in patients with pulmonary hypertension

Diabetes complicates management in a number of disease states and adversely impacts survival; how diabetes affects patients with pulmonary hypertension (PH) has not been well characterized. With insulin resistance having recently been demonstrated in PH, we sought to examine the impact of diabetes in these patients. Demographic characteristics, echo data, and invasive hemodynamic data were prospectively collected for 261 patients with PH referred for initial hemodynamic assessment. Diabetes was defined as documented insulin resistance or treatment with antidiabetic medications. Fifty-five patients (21%) had diabetes, and compared with nondiabetic patients, they were older (mean years ± SD, 61 ± 13 vs. 56 ± 16; [Formula: see text]), more likely to be black (29% vs. 14%; [Formula: see text]) and hypertensive (71% vs. 30%; [Formula: see text]), and had higher mean (±SD) serum creatinine levels (1.1 ± 0.5 vs. 1.0 ± 0.4; [Formula: see text]). Diabetic patients had similar World Health Organization functional class at presentation but were more likely to have pulmonary venous etiology of PH (24% vs. 10%; [Formula: see text]). Echo findings, including biventricular function, tricuspid regurgitation, and pressure estimates were similar. Invasive pulmonary pressures and cardiac output were similar, but right atrial pressure was appreciably higher (14 ± 8 mmHg vs. 10 ± 5 mmHg; [Formula: see text]). Despite similar management, survival was markedly worse and remained so after statistical adjustment. In summary, diabetic patients referred for assessment of PH were more likely to have pulmonary venous disease than nondiabetic patients with PH, with hemodynamics suggesting greater right-sided diastolic dysfunction. The markedly worse survival in these patients merits further study.

Thrombin stimulates VSMC proliferation through an EGFR-dependent pathway: involvement of MMP-2

In this study, the role of epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK1/2), heparin-binding EGF-like growth factor (HB-EGF), general metalloproteinases, matrix metalloproteinases-2 (MMP-2) in mediating the mitogenic action of thrombin in rat vascular smooth muscle cells (VSMC) was investigated. The incubation of rat VSMC with thrombin (1 U/ml) for 5 min resulted in significant (p < 0.001) increase of ERK1/2 phosphorylation by 8.7 ± 0.9-fold, EGFR phosphorylation by 8.5 ± 1.3-fold (p < 0.001) and DNA synthesis by 3.6 ± 0.4-fold (p < 0.001). Separate 30-min pretreatments with EGFR tyrosine kinase irreversible inhibitor, 10 µM PD169540 (PD), and 20 µM anti-HB-EGF antibody significantly reduced thrombin-stimulated EGFR and ERK1/2 phosphorylation by 81, 72 % and by 48 and 61 %, respectively. Furthermore, the same pretreatments with PD or anti-HB-EGF antibody reduced thrombin-induced VSMC proliferation by 44 and 45 %, respectively. In addition, 30-min pretreatments with 10 µM specific MMP-2 inhibitor significantly reduced thrombin-stimulated phosphorylation of both EGFR and ERK1/2 by 25 %. Moreover, the same pretreatment with MMP-2 inhibitor reduced thrombin-induced VSMC proliferation by 45 %. These results show that the thrombin-induced DNA synthesis correlates with the level of ERK1/2 activation rather than EGFR activation. These results further suggest that thrombin acts through EGFR and ERK 1/2 signaling pathways involving MMP-2 to upregulate proliferation of VSMC.

The role of G protein coupled receptor kinases in neurocardiovascular pathophysiology

In coronary artery disease the G protein related kinases (GRKs) play a role in desensitization of β-adrenoreceptors (AR) after coronary occlusion. Targeted deletion and lowering of cardiac myocyte GRK-2 decreases the risk of post-ischemic heart failure (HF). Studies carried out in humans confirm the role of GRK-2 as a marker for the progression of HF after myocardial infarction (MI). The level of GRK-2 could be an indicator of β-AR blocker efficacy in patients with acute coronary syndrome. Elevated levels of GRK-2 are an early ubiquitous consequence of myocardial injury. In hypertension an increased level of GRK-2 was reported in both animal models and human studies. The role of GRKs in vagally mediated disorders such as vasovagal syncope and atrial fibrillation remains controversial. The role of GRKs in the pathogenesis of neurocardiological diseases provides an insight into the molecular pathogenesis process, opens potential therapeutic options and suggests new directins for scientific research.

High prevalence of previously unknown heart failure and left ventricular dysfunction in patients with type 2 diabetes

AIMS/HYPOTHESIS

The aim of this study was to assess the prevalence of (unknown) heart failure and left ventricular dysfunction in older patients with type 2 diabetes.

METHODS

In total, 605 patients aged 60 years or over with type 2 diabetes in the south west of the Netherlands participated in this cross-sectional study (response rate 48.7%), including 24 with a cardiologist-confirmed diagnosis of heart failure. Between February 2009 and March 2010, the patients without known heart failure underwent a standardised diagnostic work-up, including medical history, physical examination, ECG and echocardiography. An expert panel used the criteria of the European Society of Cardiology to diagnose heart failure.

RESULTS

Of the 581 patients studied, 161 (27.7%; 95% CI 24.1%, 31.4%) were found to have previously unknown heart failure: 28 (4.8%; 95% CI 3.1%, 6.6%) with reduced ejection fraction, and 133 (22.9%; 95% CI 19.5%, 26.3%) with preserved ejection fraction. The prevalence of heart failure increased steeply with age. Heart failure with preserved ejection fraction was more common in women. Left ventricular dysfunction was diagnosed in 150 patients (25.8%; 95% CI 22.3%, 29.4%); 146 (25.1%; 95% CI 21.6%, 28.7%) had diastolic dysfunction.

CONCLUSIONS/INTERPRETATION

This is the first epidemiological study that provides exact prevalence estimates of (previously unknown) heart failure and left ventricular dysfunction in a representative sample of patients with type 2 diabetes. Previously unknown heart failure and left ventricular dysfunction are highly prevalent. Physicians should pay special attention to 'unmasking' these patients.

Physiological and pharmacological roles of vascular nucleoside transporters

Adenosine modulates various vascular functions such as vasodilatation and anti-inflammation. The local concentration of adenosine in the vicinity of adenosine receptors is fine tuned by 2 classes of nucleoside transporters: equilibrative nucleoside transporters (ENTs) and concentrative nucleoside transporters (CNTs). In vascular smooth muscle cells, 95% of adenosine transport is mediated by ENT-1 and the rest by ENT-2. In endothelial cells, 60%, 10%, and 30% of adenosine transport are mediated by ENT-1, ENT-2, and CNT-2, respectively. In vitro studies show that glucose per se increases the expression level of ENT-1 via mitogen-activating protein kinase-dependent pathways. Similar results have been demonstrated in diabetic animal models. Hypertension is associated with the increased expression of CNT-2. It has been speculated that the increase in the activities of ENT-1 and CNT-2 may reduce the availability of adenosine to adenosine receptors, thereby weakening the vascular functions of adenosine. This may explain why patients with diabetes and hypertension suffer greater morbidity from ischemia and atherosclerosis. No oral hypoglycemic agents can inhibit ENTs, but an exception is troglitazone (a thiazolidinedione that has been withdrawn from the market). ENTs are also sensitive to dihydropyridine-type calcium-channel blockers, particularly nimodipine, which can inhibit ENT-1 in the nanomolar range. Those calcium-channel blockers are noncompetitive inhibitors of ENTs, probably working through the reversible interactions with allosteric sites. The nonsteroidal anti-inflammatory drug sulindac sulfide is a competitive inhibitor of ENT-1. In addition to their original pharmacological actions, it is believed that the drugs mentioned above may regulate vascular functions through potentiation of the effects of adenosine.

Gain of function of cardiac ryanodine receptor in a rat model of type 1 diabetes

AIMS

Ventricular myocytes isolated from hearts of streptozotocin (STZ)-diabetic rats exhibit increased spontaneous Ca(2+) release. Studies attribute this defect to an enhancement in activity of type 2 ryanodine receptor (RyR2). To date, underlying reasons for RyR2 dysregulation remain undefined. This study assesses whether the responsiveness of RyR2 following stimulation by intrinsic ligands is being altered during experimental type 1 diabetes (T1D).

METHODS AND RESULTS

M-mode echocardiography established a cardiomyopathy in 8 weeks STZ-diabetic rats. Confocal microscopy confirmed an increase in the spontaneous Ca(2+) release in isolated ventricular myocytes. Western blots revealed no significant change in steady-state levels of the RyR2 protein. When purified to homogeneity and incorporated into planar lipid bilayers, RyR2 from STZ-diabetic rats (dRyR2) exhibited reduced current amplitude at ±35 mV. dRyR2 was also more responsive to intrinsic cytoplasmic activators Ca(2+), adenosine triphosphate, and cyclic adenosine diphosphate ribose and less responsive to the cytoplasmic deactivator Mg(2+). Threshold for the activation of RyR2 by trans (luminal) Ca(2+) was also reduced. These changes were independent of phosphorylation at Ser2808 and Ser2814. Two weeks of insulin treatment starting after 6 weeks of diabetes blunted the phenotype change, indicating that the gain of function is specific to the diabetes and not the result of STZ interacting directly with RyR2.

CONCLUSION

These data show, for the first time, that RyR2 is acquiring a gain-of-function phenotype independent of its phosphorylation status during T1D and provides new insights for the enhanced spontaneous Ca(2+) release in myocytes from T1D rats.

Early recognition of heart failure in patients with diabetes type 2 in primary care. A prospective diagnostic efficiency study. (UHFO-DM2)

Background

We hypothesize that the prevalence of unknown heart failure in diabetic patients aged 60 years and over is relatively high (15% or more) and that a cost-effective strategy can be developed to detect heart failure in these patients. The strategy is expected to include some signs and symptoms (such as dyspnoea, orthopnoea, pulmonary crepitations and laterally displaced apical beat), natriuretic peptide measurements (Amino-terminal B-type natriuretic peptide) and possibly electrocardiography. In a subset of patients straightforward echocardiography may show to be cost-effective. With information from our study the detection of previously unknown heart failure in diabetic patients could be improved and enable the physician to initiate beneficial morbidity and mortality reducing heart failure treatment more timely.

Primary objectives

- To assess the prevalence of (previously unrecognised) heart failure in primary care patients with diabetes type 2.

- To establish the most cost-effective diagnostic strategy to detect unrecognised heart failure in these patients.

Secondary objectives

- To assess the impact of heart failure, and the combination of a new diagnosis with accordingly treatment in patients with diabetes type 2 on health status.

Methods/Design

Design: A prospective diagnostic efficiency study.

Patient population: Patients aged 60 years and older with diabetes type 2 from primary care, enlisted with the diabetes service of the Diagnostic Center in Etten-Leur (SHL)

All participants will be investigated at the cardiology out-patient department of the regional hospital (Oosterschelde Hospital in Goes, Zeeland, the Netherlands) during a single 1.5 hour standardised diagnostic assessment, including history taking, physical examination, electrocardiography, echocardiography, blood tests, and Health status questionnaires. Patients will be asked if we can contact them afterwards for follow-up and for repeating the questionnaires after three and 12 months.

Main study parameters/endpoints: Prevalence (with exact 95% confidence intervals) of (previously unrecognised) heart failure (systolic and 'isolated' diastolic) and the diagnostic value of signs and symptoms, NT-proBNP, electrocardiography and a combination of these items. The cost-effectiveness of different diagnostic strategies. Impact of heart failure and the combination of a new diagnosis with accordingly treatment on health status.

Trial registration

CCMO register NL2271704108

Pre-exercise cardiology screening guidelines for asymptomatic patients with diabetes

Coronary heart disease is a major cause of morbidity and mortality in persons with diabetes mellitus. Exercise is an important cornerstone in the treatment and management of diabetes but is also associated with a heightened risk of sudden cardiac death in those with occult coronary heart disease. Before beginning a physical activity program that involves anything greater than moderate intensity exercise, consideration should be given to screening asymptomatic persons with diabetes for silent myocardial ischemia.

Interval training normalizes cardiomyocyte function, diastolic Ca2+ control, and SR Ca2+ release synchronicity in a mouse model of diabetic cardiomyopathy

RATIONALE

In the present study we explored the mechanisms behind excitation-contraction (EC) coupling defects in cardiomyocytes from mice with type-2 diabetes (db/db).

OBJECTIVE

We determined whether 13 weeks of aerobic interval training could restore cardiomyocyte Ca(2+) cycling and EC coupling.

METHODS AND RESULTS

Reduced contractility in cardiomyocytes isolated from sedentary db/db was associated with increased diastolic sarcoplasmic reticulum (SR)-Ca(2+) leak, reduced synchrony of Ca(2+) release, reduced transverse (T)-tubule density, and lower peak systolic and diastolic Ca(2+) and caffeine-induced Ca(2+) release. Additionally, the rate of SR Ca(2+) ATPase-mediated Ca(2+) uptake during diastole was reduced, whereas a faster recovery from caffeine-induced Ca(2+) release indicated increased Na(+)/Ca(2+)-exchanger activity. The increased SR-Ca(2+) leak was attributed to increased Ca(2+)-calmodulin-dependent protein kinase (CaMKIIdelta) phosphorylation, supported by the normalization of SR-Ca(2+) leak on inhibition of CaMKIIdelta (AIP). Exercise training restored contractile function associated with restored SR Ca(2+) release synchronicity, T-tubule density, twitch Ca(2+) amplitude, SR Ca(2+) ATPase and Na(+)/Ca(2+)-exchanger activities, and SR-Ca(2+) leak. The latter was associated with reduced phosphorylation of cytosolic CaMKIIdelta. Despite normal contractile function and Ca(2+) handling after the training period, phospholamban was hyperphosphorylated at Serine-16. Protein kinase A inhibition (H-89) in cardiomyocytes from the exercised db/db group abolished the differences in SR-Ca(2+) load when compared with the sedentary db/db mice. EC coupling changes were observed without changes in serum insulin or glucose levels, suggesting that the exercise training-induced effects are not via normalization of the diabetic condition.

CONCLUSIONS

These data demonstrate that aerobic interval training almost completely restored the contractile function of the diabetic cardiomyocyte to levels close to sedentary wild type.

The association of diabetes and older age with the absence of chest pain during acute coronary syndromes

Cardiac autonomic neuropathy associated with diabetes can cause silent myocardial ischemia and may influence the way that patients perceive symptoms of acute coronary syndromes (ACS). The purpose of this study was to examine symptoms of ACS in patients with and without diabetes while controlling for length of time with diabetes. A convenience sample of 256 patients from two large medical centers in the Midwest participated. Patients with diabetes comprised 33.2% of the sample and reported significantly less chest pain and more unusual fatigue. Patients with diabetes of longer duration (10 or more years) reported more difficulty breathing than did patients with diabetes of shorter duration (fewer than 10 years). Older patients with the same diabetes status also reported less chest pain. For older patients and for patients with diabetes, lack of chest pain during ACS could delay treatment and is thus a concern.

Symptoms Across the Continuum of Acute Coronary Syndromes: Differences Between Women and Men

Background The urgency and level of care provided for acute coronary syndromes partially depends on the symptoms manifested.

Objectives To detect differences between women and men in the type, severity, location, and quality of symptoms across the 3 clinical diagnostic categories of acute coronary syndromes (unstable angina, myocardial infarction without ST-segment elevation, and myocardial infarction with ST-segment elevation) while controlling for age, diabetes, functional status, anxiety, and depression.

Methods A convenience sample of 112 women and 144 men admitted through the emergency department and hospitalized for acute coronary syndromes participated. Recruitment took place at 2 urban teaching hospitals in the Midwest. Data were collected during structured interviews in each patient’s hospital room. Forty-eight symptom descriptors were assessed. Demographic characteristics, health history, functional status, anxiety, and depression levels also were measured.

Results Regardless of clinical diagnostic category, women reported significantly more indigestion (β = 0.25; confidence interval [CI] = 0.01–0.49), palpitations (β = 0.31; CI = 0.06–0.56), nausea (β = 0.37; CI = 0.10–0.65), numbness in the hands (β = 0.29; CI = 0.02–0.57), and unusual fatigue (β = 0.60; CI = 0.27–0.93) than men reported. Differences between men and women in dizziness, weakness, and new-onset cough did differ by diagnosis. Reports of chest pain did not differ between men and women.

Conclusions Women with acute coronary syndromes reported a higher intensity of 5 symptoms (but not chest pain) than men reported. Whether differences between the sexes in less typical symptoms are clinically significant remains unclear.

Intracardiac lipid accumulation, lipoatrophy of muscle cells and expansion of myocardial infarction in type 2 diabetic patients

The overall mortality of diabetic patients after myocardial infarction is 3-4 times higher than non-diabetics. The cellular mechanisms underlying such a poor clinical prognosis remain incompletely understood. Recent reports suggest that lipotoxicity associated with impaired liporegulation is among the leading factors in the pathogenesis of type 2 diabetes. The goal of this study was to investigate whether excess lipid accumulation specifically in heart muscle cells contributes to the expansion of myocardial infarction in type 2 diabetic patients. Comparative structural analysis of cardiac tissue was performed on autopsy samples from the infracted hearts of diabetic and non-diabetic individuals with special reference to the expansion of the infarction, degenerative changes, lipoatrophy, cell death, and replacement fibrosis. We found that progressive accumulation of lipids in cardiac myocytes was accompanied by considerable loss of myofibrils and was frequently observed in the heart tissue of type 2 diabetic patients. This indicates that disassembly of the contractile apparatus in the cells infiltrated with lipids weakens their capability for functional activity. Analysis of degenerative changes in the diabetic tissue has shown that lipid-laden cardiac myocytes were more susceptible to necrotic and apoptotic cells death leading to expansion of the infarction and the development of progressive focal replacement fibrosis both in the perinecrotic zone and in the areas located far from the site of injury. Our data show that lipoatrophy and loss of muscle cells during the post-infarction period aggravate the functional impairment in the diabetic heart and limits its adaptive capacity for compensatory remodeling. This suggests that lipotoxic myocardial injury associated with defects of lipid metabolism in type 2 diabetes predisposes its evolution toward congestive heart failure and is an important factor contributing to a high mortality following infarction.

Interactions between microvascular and macrovascular disease in diabetes: pathophysiology and therapeutic implications

Convention partitions the complications of diabetes into two main subtypes. First are the diabetes-specific microvascular complications of retinopathy, nephropathy and neuropathy; second are the atherothrombotic macrovascular complications that account for the majority of premature deaths. Pathological interactions between microvascular and macrovascular complications, for example, nephropathy and macrovascular disease, are common. Similar mechanisms and shared risk factors drive the development and progression of both small and large vessel disease. This concept has therapeutic implications. Mounting evidence points to the need for multifactorial strategies to prevent vascular complications in subjects with diabetes and/or the metabolic syndrome. We advocate a combined therapeutic approach that addresses small and large vessel disease. Preferential use should be made of drug regimens that (i) maximize vascular protection, (ii) reduce the risk of iatrogenic vascular damage and (iii) minimize the increasing problem of polypharmacy.

Increased prevalence of ventricular fibrillation in patients with type 2 diabetes mellitus

Diabetes mellitus (DM) is an independent risk for cardiovascular disease. Furthermore, patients with DM have increased risk for ventricular arrhythmia that is thought to be secondary to coronary artery disease (CAD) or congestive heart failure (CHF). We hypothesized that DM may cause ventricular arrhythmias independent of CAD or CHF. Using a large database, we evaluated the occurrence of ventricular fibrillation in patients with DM adjusting for CAD and CHF. We used patient treatment files (PTF), documents of inpatients' admissions containing discharge diagnoses (ICD-9 codes) from all Veterans Health Administration Hospitals. The patients were stratified in two groups: ICD-9 code for DM (293 124) and a control group with ICD-code for hypertension (HTN) but no DM (552 623). ICD-9 codes for ventricular fibrillation were used for this study. We performed uni- and multivariant analysis adjusting for comorbid conditions. Ventricular fibrillation was present in 563 (0.2%) vs 781 (0.1%) in the control group. Using multivariate analysis, DM remained independently associated with ventricular fibrillation (odds ratio: 1.7; confidence interval: 1.5-1.9; P < 0.000). Patients with DM have significantly higher prevalence of ventricular fibrillation independent of CAD or CHF, which in part may explain the higher risk of sudden death in patients with DM.

Oxidative stress, glucose metabolism, and the prevention of type 2 diabetes: pathophysiological insights

With the rising epidemic of type 2 diabetes worldwide, including the United States, the death and disability due to the suboptimal control of cardiovascular disease associated with this epidemic has made prevention of type 2 diabetes emerge as a primary strategic intervention. Several modalities have been assessed in large randomized controlled trials for diabetes prevention such as lifestyle interventions and various pharmacologic agents. Included in these agents are metformin, thiazolidinediones, acarbose, angiotensin converting enzyme inhibitors, as well as angiotensin receptor blockers. Abrogation of oxidative stress appears to be a common soil hypothesis that explains the favorable effects of these agents on glucose metabolism, including the prevention of diabetes and its complications. This comprehensive review highlights the role of oxidative stress in the pathogenesis of diabetes, with emphasis on the major clinical trials conducted on prevention of type 2 diabetes.

Diabetes as a risk factor for cardiac conduction defects: a review

Diabetes mellitus (DM) is a major risk factor for cardiovascular disease and mortality with increasing prevalence in the ageing population. Coronary artery disease is the major cardiovascular abnormality in DM patients. Cardiomyopathy and left ventricular hypertrophy are two other known associated cardiovascular abnormalities. There are a few non-randomized studies reporting increased prevalence of cardiac conduction abnormalities, such as right bundle branch block (RBBB), bifascicular block and high degree atrioventricular (AV)-block but not left bundle branch block (LBBB), in DM patients. Most clinicians are not aware of this association, and it is rarely mentioned in the published reviews about cardiovascular abnormalities in this population. The cause of cardiac conduction abnormalities in DM patients is not known. If autonomic neuropathy or DM-associated cardiovascular disease plays a role, it remains unknown. The goal of this manuscript is to review the current literature about the risk of conduction abnormalities in DM patients. For this study, Medline, Google and published books were searched and reviewed for any references that matched cardiac conduction abnormalities, AV-block, BBB for bundle branch block, LBBB, RBBB, bifascicular block, autonomic neuropathy and DM.

Detection of cardiac small vessel disease by adenosine-stress magnetic resonance

BACKGROUND

Patients testing positive for myocardial ischemia but without significant coronary artery (CA) stenosis in coronary angiography (CXA) are characterized as having "small vessel disease" (SVD). The aim of our study was to identify these patients by stress perfusion cardiac magnetic resonance (CMR).

METHODS

317 patients with suspected myocardial ischemia and clinical indication for CXA were scanned < 72 h before CXA in a whole-body 1.5T scanner. After 3 min of adenosine infusion (140 microg/kg/min), a myocardial first-pass perfusion sequence in 4-5 contiguous short-axis orientations using a Gadolinium-based contrast agent (0.1 mmol/kg) was performed. Images were analyzed qualitatively by two independent and blinded investigators.

RESULTS

Perfusion deficits were detected in 93% of our patients. In 78% of patients with relevant perfusion delay, perfusion deficits extended to > 1/3 of the wall thickness in > or = 2 myocardial segments, persisted for > 5 heartbeats and were regarded as relevant coronary macroangiopathy. All of these patients had significant CA stenosis (60% had luminal narrowing > 70% and 18% had 50-70%). 22% of the patients had perfusion deficits affecting < or = 1/3 of wall thickness with persistence for < or = 5 heartbeats and were regarded as having SVD. None of these patients had a CA stenosis of > 50% or received CA revascularization. These patients more frequently had hypertension (p<0.0001), diabetes (p<0.05) and circumferential perfusion deficits (p<0.0001) than other patients.

CONCLUSION

Stress perfusion CMR allows non-invasive differentiation between patients with significant CA stenosis and patients with SVD caused by hypertension and/or diabetes based on the temporal and spatial extent of perfusion deficits. Patients with SVD more often have diffuse perfusion deficits with shorter persistence than patients with significant CA disease.

Lipid abnormalities are prevalent in youth with type 1 and type 2 diabetes: the SEARCH for Diabetes in Youth Study

OBJECTIVE

Assessment of the prevalence of serum lipid abnormalities in US youth with type 1 or type 2 diabetes.

STUDY DESIGN

The SEARCH for Diabetes in Youth Study was a cross-sectional, population-based study, conducted in six centers. Subjects were 2448 youth with diabetes who had a study examination. Outcome measures were fasting measures of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, and non-HDL-C. Analysis was descriptive.

RESULTS

The overall prevalence of high TC concentration (>240 mg/dL) was 5%; the overall prevalence of high LDL-C (>160 mg/dL) was 3%, and the overall prevalence of high triglyceride (>400 mg/dL) was 2%. About half of the participants (48%) had an LDL-C concentration above the optimal level of 100 mg/dL. Among youth ages 10+, the prevalence of abnormal lipids was higher in type 2 (n = 283) than in type 1 diabetes (n = 1963): 33% versus 19% had TC concentration >200 mg/dL; 24% versus 15% had LDL-C concentration >130 mg/dL; 29% versus 10% had triglyceride concentration >150 mg/dL; 44% versus 12% had HDL-C concentration <40 mg/dL. Only 1% of youth were receiving pharmacologic therapy for dyslipidemia.

CONCLUSIONS

A substantial proportion of young patients with diabetes have abnormal serum lipids.

Anemia and cardiovascular disease in diabetic nephropathy

Cardiovascular disease (CVD) is the major cause of morbidity and mortality in people with diabetes and in those with chronic kidney disease (CKD). Diabetes, occurring in epidemic proportions in the United States and worldwide, is also the leading cause of CKD and kidney failure. Identification of modifiable risk factors for CVD in patients with diabetes and CKD is thus of paramount importance. Anemia is increasingly recognized as a potential CVD risk factor in patients with diabetic nephropathy, in whom it is generally more severe and occurs at an earlier stage of CKD. In this review, we discuss the epidemiologic evidence, pathophysiologic mechanisms, and the current research findings, highlighting the role of anemia as a potential modifiable risk factor for CVD in patients with diabetic nephropathy, a particularly vulnerable population for CVD.

Diabetes mellitus is a strong, independent risk for atrial fibrillation and flutter in addition to other cardiovascular disease

BACKGROUND

Diabetes mellitus (DM) is a major risk factor for atherosclerosis. There is a controversy in literature about correlation between DM and atrial fibrillation. The goal of this study was to evaluate DM as a risk factor for atrial fibrillation or flutter using a very large database.

METHOD

Patient treatment files (PTF) containing discharge diagnoses were utilized using ICD-9 codes of inpatient treatment from Veterans Health Administration Hospitals (VAH). Patients with type II DM (ICD-9 code 250.0) (293,124) discharged from the VAH between 1990 and 2000. Non-matched controls without DM but with hypertension (552,624) were selected from the same PTF. By using multi-variate logistic regressions, the occurrence of atrial fibrillation, atrial flutter, CHF, CAD and LVH was compared.

RESULTS

Atrial fibrillations occurred in 43,674 (14.9%) DM patients vs. 57,077 (10.3%) in the control group (p<0.0001). Atrial flutter occurred in 11,852 (4%) of DM patients vs. 13,554 (2.5%) of the control group (p<0.0001). Using multi-variant analysis, DM remained independently associated with atrial fibrillation with an OR of 2.13, (95% CI: 2.10 to 2.16; p<0.0001) and flutter (OR 2.20, CI: 2.15 to 2.26; p<0.0001). Furthermore, CHF (OR 3.12, CI: 3.09 to 3.16; p<0.0001), LVH (OR 1.85, CI: 1.77 to 1.92; p<0.0001) and CAD (OR 2.39, CI: 2.34 to 2.44; p<0.0001) were also independently associated with DM.

CONCLUSION

This is the first large-scale study finding DM as a strong, independent risk for the occurrence of atrial fibrillation and flutter and other cardiovascular disease.

Increased Prevalence of Third-Degree Atrioventricular Block in Patients With Type II Diabetes Mellitus

BACKGROUND

Diabetes mellitus (DM) is a major risk for cardiovascular disease and mortality. There is some evidence that third-degree atrioventricular (AV) block occurs more commonly in patients with DM. In this study, we evaluated any possible association between DM and third-degree AV block using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes in a very large inpatient database.

METHOD

We used patient treatment files containing discharge diagnoses using ICD-9 codes of inpatient treatment from all Veterans Health Administration hospitals. The cohort was stratified using the ICD-9-CM code for DM (n = 293,124), a control group with hypertension but no DM (n = 552,623), and the ICD-9 code for third-degree AV block (426.0) and smoking (305.1, V15.82). We performed multivariate analysis adjusting for coronary artery disease, congestive heart failure, smoking, and hyperlipidemia. Continuous and binary variables were analyzed using chi2 and Fisher exact tests.

RESULTS

Third-degree AV block diagnosis was present in 3,240 of DM patients (1.1%) vs 3,367 patients (0.6%) in the control group. Using multivariate analysis, DM remained strongly associated with third-degree AV block (odds ratio, 3.1; 95% confidential interval, 3.0 to 3.3; p < 0.0001).

CONCLUSION

Third-degree AV block occurs significantly more in patients with DM. This finding may, in part, explain the high cardiovascular mortality in DM patients.

Role of exercise training on cardiovascular disease in persons who have type 2 diabetes and hypertension

Exercise training is an essential component in the medical management of patients who have type 2 diabetes and hypertension. Regular exercise improves the cardiovascular health of individuals who have these conditions through multiple mechanisms (Fig. 1). These mechanisms include improvements in endothelial vasodilator function,left ventricular diastolic function, arterial stiffness.systematic inflammation, and reducing left ventricular mass. Exercise training also reduces total and abdominal fat, which mediate improvements in insulin sensitivity and blood pressure, and possibly, endothelial function. Persons who are in a prediabetic stage or those who have the metabolic syndrome may be able to prevent or delay the progression to overt diabetes by adopting a healthier lifestyle, of which increasing habitual levels of physical activity isa vital component. Most persons who have diabetes and hypertension or are at risk for these conditions should be able to initiate an exercise program safely after appropriate medical screen-ing and the establishment of an individualized exercise prescription. Despite the increasing amount of evidence that shows the benefits of exercise training, this modality of prevention and treatment continues to be underused. Although patients' lack of knowledge of the benefits of exercise or lack of motivation contributes to this underuse, a lack of clear and specific guidelines from health care professionals also is an important factor. Clinicians need to educate patients about the benefits of exercise for managing their type 2 diabetes and assist in formulating specific advice for increasing physical activity. Specific instructions should be given to patients, rather than general advice, such as "you should exercise more often." Many cardiac re-habilitation and clinical exercise programs can accommodate patients who have type 2 diabetes and hypertension. Such programs can establish individualized exercise prescriptions and provide an environment that is conducive for "lifestyle change" that underlies long-term compliance to exercise and risk factor modification.