Abnormal Glucose Tolerance Contributes to the Progression of Chronic Heart Failure in Patients with Dilated Cardiomyopathy

Prediabetes and insulin resistance in a population of patients with heart failure and reduced or preserved ejection fraction but without diabetes, overweight or hypertension

Background

The relationships between glucose abnormalities, insulin resistance (IR) and heart failure (HF) are unclear, especially regarding to the HF type, i.e., HF with reduced (HFrEF) or preserved (HFpEF) ejection fraction. Overweight, diabetes and hypertension are potential contributors to IR in persons with HF. This study aimed to evaluate the prevalence of prediabetes and IR in a population of Vietnamese patients with HFrEF or HFpEF but no overweight, diabetes or hypertension, in comparison with healthy controls, and the relation between prediabetes or IR and HF severity.

Methods

We conducted a prospective cross-sectional observational study in 190 non-overweight normotensive HF patients (114 with HFrEF and 76 with HFpEF, 92.6% were ischemic HF, mean age was 70.1 years, mean BMI 19.7 kg/m²) without diabetes (neither known diabetes nor newly diagnosed by OGTT) and 95 healthy individuals (controls). Prediabetes was defined using 2006 WHO criteria. Glucose and insulin levels were measured fasting and 2 h after glucose challenge. IR was assessed using HOMA-IR and several other indexes.

Results

Compared to controls, HF patients had a higher prevalence of prediabetes (63.2% vs 22.1%) and IR (according to HOMA-IR, 55.3% vs 26.3%), higher HOMA-IR, insulin/glucose ratio after glucose and FIRI, and lower ISIT0 and ISIT120 (< 0.0001 for all comparisons), with no difference for body weight, waist circumference, blood pressure and lipid parameters. Prediabetes was more prevalent (69.3% vs 53.9%, p = 0.03) and HOMA-IR was higher (p < 0.0001) in patients with HFrEF than with HFpEF. Among both HFrEF and HFpEF patients, those with prediabetes or IR had a more severe HF (higher NYHA functional class and NT-proBNP levels, lower ejection fraction; p = 0.04–< 0.0001) than their normoglycemic or non-insulinresistant counterparts, with no difference for blood pressure and lipid parameters.

Conclusion

In non-diabetic non-overweight normotensive patients with HF, the prevalence of prediabetes is higher with some trend to more severe IR in those with HFrEF than in those with HFpEF. Both prediabetes and IR are associated with a more severe HF. The present data support HF as a culprit for IR. Intervention strategies should be proposed to HF patients with prediabetes aiming to reduce the risk of incident diabetes. Studies should be designed to test whether such strategies may translate into an improvement of further HF-related outcomes.

Predicting heart failure events in patients with coronary heart disease and impaired glucose tolerance: Insights from the Acarbose Cardiovascular Evaluation (ACE) trial

AIMS

Heart failure is a fatal complication of type 2 diabetes but little is known about its incidence in people with impaired glucose tolerance (IGT). We used Acarbose Cardiovascular Evaluation (ACE) trial data to identify predictors of hospitalisation for heart failure (hHF) or cardiovascular (CV) death in patients with coronary heart disease (CHD) and IGT randomised to acarbose or placebo.

METHODS

Independent hHF/CV death risk factors were determined using Cox proportional hazards models, with participants censored at first hHF event, CV death, or end of follow-up.

RESULTS

During median 5-year follow-up, the composite outcome of hHF/CV death occurred in 393 (6.0%) participants. Significant hHF/CV death multivariate predictors were higher age and plasma creatinine, and prior heart failure (HF), myocardial infarction (MI), atrial fibrillation (AF) and stroke. Acarbose, compared with placebo, did not reduce hHF/CV death (hazard ratio [HR] 0.89, 95% CI 0.64-1.24, P = 0.48) or hHF (HR 0.90, 95% CI 0.74-1.10, P = 0.32).

CONCLUSIONS

Patients with CHD and IGT at greater risk of hHF/CV death were older with higher plasma creatinine, prior HF, MI, AF or stroke. Addition of acarbose to optimised CV therapy to reduce post-prandial glucose excursions did not reduce the risk of hHF/CV death or hHF.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, number NCT00829660, and the International Standard Randomised Controlled Trial Number registry, number ISRCTN91899513.

Impaired glucose tolerance and albuminuria in patients with chronic heart failure: a subanalysis of the SUPPORT trial

AIMS

The study aims to evaluate the prognostic significance of impaired glucose tolerance (IGT) with reference to albuminuria in patients with chronic heart failure (CHF).

METHODS AND RESULTS

We examined 535 CHF patients (mean 66 years, women 25%) in the control arm of our SUPPORT trial, in which we examined additive impact of olmesartan in hypertensive patients with symptomatic CHF treated with β-blockers and/or angiotensin-converting enzyme inhibitors. We examined the association between glycaemic abnormality (assessed by 75 g of oral glucose tolerance test) and albuminuria for a composite outcome of all-cause death, myocardial infarction, stroke, and HF hospitalization. IGT patients (N = 113, mean 67.2 years) were older and more frequently treated with β-blockers compared with those with normal glucose regulation (N = 142, mean 64.0 years) and those with diabetes mellitus (N = 280, mean 65.7 years). Multivariable Cox proportional hazard models revealed that, as compared with normal glucose regulation (NGR), IGT was associated with increased risk of the outcome when complicated by albuminuria [hazard ratio (HR) 2.25; 95% confidence interval (CI) 1.14-4.42; P = 0.019] but not when uncomplicated by albuminuria (HR 0.76; 95% CI 0.35-1.60, P = 0.47) (P for interaction = 0.041). This was also the case for diabetes mellitus and albuminuria (HR 2.06; 95% CI 1.17-3.61; P = 0.012). Among IGT patients without albuminuria, 21 (29%) developed albuminuria at 1-year visit, which was again associated with poor prognosis (HR 7.36; 95% CI 1.39-38.98, P = 0.019).

CONCLUSIONS

These results indicate that IGT is associated with poor prognosis when complicated by albuminuria in CHF patients, demonstrating the importance of combined early stages of glucose intolerance and renal dysfunction in the management of CHF.

Heart failure in the patient with diabetes: Epidemiology, aetiology, prognosis, therapy and the effect of glucose-lowering medications

In people with type 2 diabetes the frequency of heart failure (HF) is increased and mortality from HF is higher than with non-diabetic HF. The increased frequency of HF is attributable to the cardiotoxic tetrad of ischaemic heart disease, left ventricular hypertrophy, diabetic cardiomyopathy and an extracellular volume expansion resistant to atrial natriuretic peptides. Activation of the renin-angiotensin-aldosterone system and sympathetic nervous systems results in cardiac remodelling, which worsens cardiac function. Reversal of remodelling can be achieved, and cardiac function improved in people with HF with reduced ejection fraction (HFrEF) by treatment with angiotensin-converting enzyme inhibitors and β-blockers. However, with HF with preserved ejection fraction (HFpEF), only therapy for the underlying risk factors helps. Blockers of mineralocorticoid receptors may be beneficial in both HFrEF and HFpEF. Glucose-lowering drugs can have a negative effect (insulin, sulphonylureas, dipeptidyl peptidase-4 inhibitors and thiazolidinediones), a neutral effect (α-glucosidase inhibitors and glucagon-like peptide-1 receptor agonists) or a positive effect (sodium-glucose co-transporter-2 inhibitors and metformin).

The effect of luseogliflozin and alpha-glucosidase inhibitor on heart failure with preserved ejection fraction in diabetic patients: rationale and design of the MUSCAT-HF randomised controlled trial

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is a strong risk factor for coronary artery disease and heart failure, particularly heart failure with preserved ejection fraction (HFpEF). The aim of the ongoing MUSCAT-HF (It stands for Prospective Comparison of Luseogliflozin and Alpha-glucosidase on the Management of Diabetic Patients with Chronic Heart Failure and Preserved Ejection Fraction) trial is to evaluate the efficacy of luseogliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, versus voglibose, an alpha-glucosidase inhibitor, using brain natriuretic peptide (BNP) as the index of therapeutic effect in T2DM patients with HFpEF.

METHODS AND ANALYSIS

A total of 190 patients with T2DM and HFpEF (ejection fraction >45%) who are drug-naïve or taking any anti-diabetic agents will be randomised (1:1) to receive luseogliflozin 2.5 mg one time per day or voglibose 0.2 mg three times per day. The patients will be stratified by age (<65 years, ≥65 years), baseline haemoglobin A1c (<8.0%, ≥8.0%), baseline BNP (<100 pg/mL, ≥100 pg/mL), baseline renal function (estimated glomerular filtration rate ≥60 mL/min/1.73 m², <60 mL/min/1.73 m²), use of thiazolidine or not and presence or absence of atrial fibrillation and flutter at screening. After randomisation, participants will receive the study drug for 12 weeks in addition to their background therapy. The primary endpoint is the proportional change in baseline BNP after 12 weeks of treatment. The key secondary endpoints are the change from baseline in the ratio of early mitral inflow velocity to mitral annular early diastolic velocity, body weight and glycaemic control after 12 weeks of treatment.

ETHICS AND DISSEMINATION

The study has been approved by the ethics committee and the patients will be included after informed consent. The results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

UMIN000018395.

The intestine responds to heart failure by enhanced mitochondrial fusion through glucagon-like peptide-1 signalling

Aims

Glucagon-like peptide-1 (GLP-1) is a neuroendocrine hormone secreted by the intestine. Its receptor (GLP-1R) is expressed in various organs, including the heart. However, the dynamics and function of the GLP-1 signal in heart failure remains unclear. We investigated the impact of the cardio-intestinal association on hypertensive heart failure using miglitol, an α-glucosidase inhibitor known to stimulate intestinal GLP-1 production.

Methods and results

Dahl salt-sensitive (DS) rats fed a high-salt diet were assigned to miglitol, exendin (9-39) (GLP-1R blocker) and untreated control groups and treated for 11 weeks. Control DS rats showed marked hypertension and cardiac dysfunction with left ventricular dilatation accompanied by elevated plasma GLP-1 levels and increased cardiac GLP-1R expression as compared with age-matched Dahl salt-resistant (DR) rats. Miglitol further increased plasma GLP-1 levels, suppressed adverse cardiac remodelling, and mitigated cardiac dysfunction. In cardiomyocytes from miglitol-treated DS hearts, mitochondrial size was significantly larger with denser cristae than in cardiomyocytes from control DS hearts. The change in mitochondrial morphology reflected enhanced mitochondrial fusion mediated by protein kinase A activation leading to phosphorylation of dynamin-related protein 1, expression of mitofusin-1 and OPA-1, and increased myocardial adenosine triphosphate (ATP) content. GLP-1R blockade with exendin (9-39) exacerbated cardiac dysfunction and led to fragmented mitochondria with disarrayed cristae in cardiomyocytes and reduction of myocardial ATP content. In cultured cardiomyocytes, GLP-1 increased expression of mitochondrial fusion-related proteins and ATP content. When GLP-1 and exendin (9-39) were administered together, their effects cancelled out.

Conclusions

Increased intestinal GLP-1 secretion is an adaptive response to heart failure that is enhanced by miglitol. This could be an effective strategy for treating heart failure through regulation of mitochondrial dynamics.

Heart Failure: Epidemiology, Pathophysiology, and Management of Heart Failure in Diabetes Mellitus

This article briefly discusses the epidemiology of heart failure and diabetes and summarizes the key findings from the recent cardiovascular outcome trials in patients with type 2 diabetes, with a focus on heart failure as an endpoint.

Impact of Either GLP-1 Agonists or DPP-4 Inhibitors on Pathophysiology of Heart Failure

Since diabetes mellitus (DM) is the most common cause of heart failure (HF), it is critically important to clarify whether incretin hormones including glucagon-like peptide-1 (GLP-1), which play an important role in blood glucose control, mediate cardioprotection. There are many lines of basic research evidence indicating that GLP-1 improves the pathophysiology of HF: In murine and canine HF models, either GLP-1 analogues or DPP-IV inhibitors improved cardiac functions. The first question that arises is how either GLP-1 analogues or DPP-IV inhibitors mediate cardioprotection. Cardiovascular diseases are tightly linked to impaired glucose tolerance (IGT): IGT is not only one of the causes of cardiovascular events but also the result of HF. Indeed, the treatment of IGT improved HF, showing that one of the mechanisms attributable to DPP-IV inhibitors is related to the improvement of IGT. Intriguingly, either DPP-IV inhibitors or GLP-1 analogues mediate cardioprotection even without IGT, suggesting two possible explanations: One is that GLP-1 analogues directly activate the prosurvival kinases, such as Akt and Erk1/2, and another is that DPP-IV inhibition increases cardioprotective peptides such as BNP and SDF-1α. The next question is whether cardioprotection is translated to clinical medicine. Small scale clinical trials proved their cardioprotective effects; however, several large scale clinical trials have not proved the beneficial effects of DPP-IV inhibitors. Taken together, GLP-1 analogues or DPP-IV inhibitors can mediate cardioprotection, however, what needs to be clarified is who mainly receives their benefits among the patients with cardiovascular diseases and/or DM.

Dipeptidyl-peptidase IV inhibition improves pathophysiology of heart failure and increases survival rate in pressure-overloaded mice

Incretin hormones, including glucagon-like peptide-1 (GLP-1), a target for diabetes mellitus (DM) treatment, are associated with cardioprotection. As dipeptidyl-peptidase IV (DPP-IV) inhibition increases plasma GLP-1 levels in vivo, we investigated the cardioprotective effects of the DPP-IV inhibitor vildagliptin in a murine heart failure (HF) model. We induced transverse aortic constriction (TAC) in C57BL/6J mice, simulating pressure-overloaded cardiac hypertrophy and HF. TAC or sham-operated mice were treated with or without vildagliptin. An intraperitoneal glucose tolerance test revealed that blood glucose levels were higher in the TAC than in sham-operated mice, and these levels improved with vildagliptin administration in both groups. Vildagliptin increased plasma GLP-1 levels in the TAC mice and ameliorated TAC-induced left ventricular enlargement and dysfunction. Vildagliptin palliated both myocardial apoptosis and fibrosis in TAC mice, demonstrated by histological, gene and protein expression analyses, and improved survival rate on day 28 (TAC with vildagliptin, 67.5%; TAC without vildagliptin, 41.5%; P < 0.05). Vildagliptin improved cardiac dysfunction and overall survival in the TAC mice, both by improving impaired glucose tolerance and by increasing GLP-1 levels. DPP-IV inhibitors represent a candidate treatment for HF patients with or without DM.

Saxagliptin Improves Glucose Tolerance but not Survival in a Murine Model of Dilated Cardiomyopathy

Glucagon-like peptide 1 (GLP-1) agonists improve myocardial function and insulin sensitivity in the setting of chronic heart failure. Endogenously produced GLP-1 peptide (7-36) is rapidly cleaved by dipeptidyl peptidase 4 (DPP4) to the 9-36 peptide, which lacks anti-hyperglycemic activity. To elucidate the effect of increased endogenous GLP-1 during heart failure progression, the DPP4 inhibitor saxagliptin or vehicle was administered by daily oral gavage to female TG9 mice, a transgenic model of dilated cardiomyopathy, starting at day of life 42, just prior to the development of detectable contractile dysfunction. Saxagliptin treatment inhibited DPP4 activity >90% and increased GLP-1 levels 4-fold following a 2 gm/kg glucose load but did not affect fasting GLP-1 levels. There was no difference in food intake or body weight between groups. At 56 days of age, oral glucose tolerance was improved in saxagliptin-versus vehicle-treated animals (AUC_0-120 1340 ± 46 and 1501 ± 43 min·mmol/L, respectively, p<0.015). In contrast to the effect of a GLP-1 agonist in TG9 mice, saxagliptin had no effect on survival (80.7 ± 4.3 days) compared to vehicle-treated mice (79.6 ± 3.6 days, p = 0.46). Taken together, these data indicate that improvement in glucose tolerance is not sufficient to improve survival. Future efforts to confirm these findings in additional models of heart failure are warranted.

Oral glucose tolerance testing in an outpatient heart failure clinic reveals a high proportion of undiagnosed diabetic patients with an adverse prognosis

AIMS

We evaluated the applicability and prognostic importance of oral glucose tolerance testing (OGTT) among outpatients with systolic heart failure (SHF).

METHODS AND RESULTS

Consecutive patients with SHF and left ventricular ejection fraction (LVEF) ≤ 45% referred to a heart failure clinic (n= 413) were included in this study. An OGTT was conducted in patients without a history of diabetes. Information on NYHA class, aetiology of SHF, LVEF, treatment, and biochemical parameters were collected at baseline. The survival status was obtained after a median follow-up time of 591 days. Of the 413 patients, 82 (20%) had known diabetes. Of the remaining 331 patients, 227 (69%) agreed to undergo an OGTT. Among the tested subjects, 136 (60%) were classified as having normal glucose tolerance (NGT), 51 (23%) impaired glucose tolerance (IGT), and 40 (18%) newly diagnosed diabetes. Assuming a similar prevalence of unrecognized diabetes among the patients who refused OGTT, the prevalence of diabetes in the total population was 34%. If only fasting blood glucose had been used, 16 of the 40 newly diagnosed diabetic patients would have been undiagnosed. During follow-up, 24 (29%) patients with known diabetes, 6 (15%) of the newly diagnosed diabetic patients, 9 (18%) of those with IGT, and 13 (9%) patients with NGT died. Patients with diabetes had higher mortality rate compared with non-diabetic patients [multivariate hazard ratio 1.89 (1.02-3.59); P = 0.047].

CONCLUSION

It is feasible to perform diabetes screening using OGTT in outpatients with SHF. A substantial proportion of patients tested were found to have unrecognized diabetes. The presence of diabetes was associated with a higher mortality rate.

HIV protease inhibitors that block GLUT4 precipitate acute, decompensated heart failure in a mouse model of dilated cardiomyopathy

The clinical use of HIV protease inhibitors is associated with insulin resistance and other metabolic changes that increase long-term cardiovascular risk. Since the failing heart has increased reliance on glucose, the influence of drug exposure on glucose homeostasis, myocardial glucose uptake, cardiac function, and survival was determined in TG9 mice, an established transgenic model of dilated cardiomyopathy generated by cardiac-specific overexpression of Cre-recombinase, as these animals progressed to overt heart failure. Beginning on day of life 75, TG9 mice and nontransgenic littermate controls were given a daily 10 mg/kg intraperitoneal injection of HIV protease inhibitors (ritonavir, lopinavir/ritonavir 4:1, atazanavir, atazanavir/ritonavir 4:1) or vehicle. Glucose tolerance testing, measurement of in vivo myocardial 2-deoxyglucose uptake, and echocardiography were performed before and 30 min following drug administration. The progression of dilated cardiomyopathy in TG9 animals was accompanied by impaired glucose tolerance, which was acutely exacerbated by exposure to ritonavir. Ritonavir and lopinavir precipitated acute, decompensated heart failure and death from pulmonary edema in TG9 mice. However, atazanavir, which does not inhibit glucose transport, had no effect. These studies demonstrate that, in the presence of dilated cardiomyopathy, HIV protease inhibitors that impair glucose transport induce acute, decompensated heart failure. The potential for HIV protease inhibitors to contribute to or exacerbate cardiomyopathy in human patients warrants further investigation.