Impaired left ventricular diastolic function in T2DM patients is closely related to glycemic control

A genetic mouse model of lean-NAFLD unveils sexual dimorphism in the liver-heart axis

Lean patients with NAFLD may develop cardiac complications independently of pre-existent metabolic disruptions and comorbidities. To address the underlying mechanisms independent of the development of obesity, we used a murine model of hepatic mitochondrial deficiency. The liver-heart axis was studied as these mice develop microvesicular steatosis without obesity. Our results unveil a sex-dependent phenotypic remodeling beyond liver damage. Males, more than females, show fasting hypoglycemia and increased insulin sensitivity. They exhibit diastolic dysfunction, remodeling of the circulating lipoproteins and cardiac lipidome. Conversely, females do not manifest cardiac dysfunction but exhibit cardiometabolic impairments supported by impaired mitochondrial integrity and β-oxidation, remodeling of circulating lipoproteins and intracardiac accumulation of deleterious triglycerides. This study underscores metabolic defects in the liver resulting in significant sex-dependent cardiac abnormalities independent of obesity. This experimental model may prove useful to better understand the sex-related variability, notably in the heart, involved in the progression of lean-NAFLD.

The Effect of Glycemic Control on Left Ventricular Function in Clinical and Experimental Diabetes

Background

Glycemic control in diabetes mellitus (DM) has not improved cardiovascular outcomes with normal left ventricular (LV) function. We assessed the effect on LV dysfunction using a canine model of LV dysfunction and DM, and in patients with DM and LV dysfunction.

Methods

Chronic LV dysfunction was produced by coronary microsphere embolization in 34 canines (15-25 kg). Following 8 weeks of stabilization, DM was induced in 24 canines and randomized to good or poor glycemic control for 3 months. Ten canines without DM were controls. Hemodynamic and Doppler echocardiographic data were obtained prior to and following pressure loading. We reviewed the Doppler-echocardiography at baseline and follow-up in 207 patients with DM with reduced ejection fraction (EF; median follow-up = 612 days) and 60 age- and sex-matched non-DM patients with normal EF. Laboratory results, medications, and incident adverse events from medical records were obtained.

Results

EF = 43.8% ± 11.2% for all canines at 8 weeks. Canines with poor glycemic control (hemoglobin [Hb]A1c = 8.05% ± 3.02%) demonstrated reduced LV mass and rate-corrected velocity of circumferential fiber shortening, compared to those with LV dysfunction (1.36 ± 0.73 vs 0.88 ± 0.13 circumference per second, P < 0.01). Good glycemic control (HbA1c = 3.88% ± 0.89%) demonstrated similar LV parameters, compared to controls (HbA1c = 2.99% ± 0.44%). EF was similar among groups. Patients with vs without DM were followed for up to 3 years. Patients with DM and poor glycemic control had reduced EF, lower rate-corrected velocity of circumferential fiber shortening = 0.93 ± 0.26 vs 1.11 ± 0.26, P < 0.001), and greater incidence of heart failure.

Conclusions

Poor glycemic control had an adverse effect on preexisting LV dysfunction experimentally and in patients with type 2 diabetes.

Pioglitazone reduces epicardial fat and improves diastolic function in patients with type 2 diabetes

AIMS

To examine the effect of pioglitazone on epicardial (EAT) and paracardial adipose tissue (PAT) and measures of diastolic function and insulin sensitivity in patients with type 2 diabetes mellitus (T2DM).

METHODS

Twelve patients with T2DM without clinically manifest cardiovascular disease and 12 subjects with normal glucose tolerance (NGT) underwent cardiac magnetic resonance imaging to quantitate EAT and PAT and diastolic function before and after pioglitazone treatment for 24 weeks. Whole-body insulin sensitivity was measured with a euglycaemic insulin clamp and the Matsuda Index (oral glucose tolerance test).

RESULTS

Pioglitazone reduced glycated haemoglobin by 0.9% (P < 0.05), increased HDL cholesterol by 7% (P < 0.05), reduced triacylglycerol by 42% (P < 0.01) and increased whole-body insulin-stimulated glucose uptake by 71% (P < 0.01) and Matsuda Index by 100% (P < 0.01). In patients with T2DM, EAT (P < 0.01) and PAT (P < 0.01) areas were greater compared with subjects with NGT, and decreased by 9% (P = 0.03) and 9% (P = 0.09), respectively, after pioglitazone treatment. Transmitral E/A flow rate and peak left ventricular flow rate (PLVFR) were reduced in T2DM versus NGT (P < 0.01) and increased following pioglitazone treatment (P < 0.01-0.05). At baseline normalized PLVFR inversely correlated with EAT (r = -0.45, P = 0.03) but not PAT (r = -0.29, P = 0.16). E/A was significantly and inversely correlated with EAT (r = -0.55, P = 0.006) and PAT (r = -0.40, P = 0.05). EAT and PAT were inversely correlated with whole-body insulin-stimulated glucose uptake (r = -0.68, P < 0.001) and with Matsuda Index (r = 0.99, P < 0.002).

CONCLUSION

Pioglitazone reduced EAT and PAT areas and improved left ventricular (LV) diastolic function in T2DM. EAT and PAT are inversely correlated (PAT less strongly) with LV diastolic function and both EAT and PAT are inversely correlated with measures of insulin sensitivity.

Left Ventricular Diastolic Function Studied with Magnetic Resonance Imaging: A Systematic Review of Techniques and Relation to Established Measures of Diastolic Function

Purpose: In recent years, cardiac magnetic resonance (CMR) has been used to assess LV diastolic function. In this systematic review, studies were identified where CMR parameters had been evaluated in healthy and/or patient groups with proven diastolic dysfunction or known to develop heart failure with preserved ejection fraction. We aimed at describing the parameters most often used, thresholds where possible, and correlation to echocardiographic and invasive measurements. Methods and results: A systematic literature review was performed using the databases of PubMed, Embase, and Cochrane. In total, 3808 articles were screened, and 102 studies were included. Four main CMR techniques were identified: tagging; time/volume curves; mitral inflow quantification with velocity-encoded phase-contrast sequences; and feature tracking. Techniques were described and estimates were presented in tables. From published studies, peak change of torsion shear angle versus volume changes in early diastole (−dφ′/dV′) (from tagging analysis), early peak filling rate indexed to LV end-diastolic volume <2.1 s⁻¹ (from LV time-volume curve analysis), enlarged LA maximal volume >52 mL/m², lowered LA total (<40%), and lowered LA passive emptying fractions (<16%) seem to be reliable measures of LV diastolic dysfunction. Feature tracking, especially of the atrium, shows promise but is still a novel technique. Conclusion: CMR techniques of LV untwisting and early filling and LA measures of poor emptying are promising for the diagnosis of LV filling impairment, but further research in long-term follow-up studies is needed to assess the ability for the parameters to predict patient related outcomes.

Sodium-glucose cotransporter 2 inhibitors represent a paradigm shift in the prevention of heart failure in type 2 diabetes patients

Recent major clinical trials of the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors in patients with type 2 diabetes have shown that they reduce three-point major adverse cardiovascular events, cardiovascular death, hospitalization for heart failure (HF) and a composite renal outcome. These beneficial effects of SGLT2 inhibitors are also evident in type 2 diabetes patients with a previous history of atherosclerotic cardiovascular disease or advanced renal disease. HF is a major determinant of the prognosis of diabetes patients. Although HF with low ejection fraction can be effectively treated with antihypertensive drugs, these treatments do not reduce mortality in HF patients with preserved ejection fraction (HFpEF). HFpEF is clinically characterized by left ventricular diastolic dysfunction, perivascular fibrosis and stiffness of cardiomyocytes, defined as "cardiomyopathy". Therefore, HFpEF is considered to be an entirely separate entity to HF with low ejection fraction. Recent studies have suggested that HFpEF might be treatable using SGLT2 inhibitors, which ameliorate visceral adiposity, insulin resistance, hyperglycemia, hyperlipidemia, volume overload, hypertension and cardiac inflammation. In the final part of the present review, we discuss the biochemical and molecular mechanisms of the effects of SGLT2 inhibitors in type 2 diabetes patients with HFpEF. These involve amelioration of the low nitric oxide production and oxidative stress, a reduction in cardiac inflammatory cytokine signaling, inhibition of Ca2+ overload, and an improvement in cardiac energy metabolism as a result of ketone body production. Investigations of the beneficial effects of SGLT2 inhibitors on cardiorenal outcomes, including hospitalization for HF, are now being carried out in preclinical and clinical studies.

An in-depth analysis of glycosylated haemoglobin level, body mass index and left ventricular diastolic dysfunction in patients with type 2 diabetes

BACKGROUND

Glycosylated hemoglobin (HbA1c) has a detrimental impact on the myocardium with left ventricular (LV) diastolic dysfunction. Obesity is a risk factor of type 2 diabetes. To understand the relationships between HbA1c, body mass index (BMI) and LV diastolic dysfunction, we performed this interaction analysis in patients with type 2 diabetes.

METHODS

Total 925 type 2 diabetes patients were selected from the patients who were diagnosed and treated at the First Affiliated Hospital of Shenzhen University. Patients' BMI levels were defined as normal (BMI < 24 kg/m²) and overweight /obese (BMI ≥ 24 kg/m²). Patients' HbA1c levels were grouped as HbA1c ≥ 9%、7% ≤ HbA1c < 9% and HbA1c < 7%. Logistic regression, stratified, interaction analysis, multivariate Cox regression and curve fitting analysis were performed to investigate the correlations and interactions between HbA1c and BMI with LV diastolic dysfunction.

RESULTS

The BMI levels were significantly associated with LV diastolic dysfunction in the patients with type 2 diabetes [adjusted model: 1.12 (1.05, 1.20), P = 0.001]. While HbA1c levels had association with LV diastolic dysfunction only in normal BMI group patients [adjusted model: 1.14 (1.01, 1.30), P = 0.0394] and curve correlation was observed. There was a significant interaction between BMI and HbA1c to affect LV diastolic dysfunction (P = 0.0335). Cox regression model analysis showed that the risk of LV diastolic dysfunction was a U type correlation with HbA1c levels in the normal weight group and the turning point was HbA1c at 10%. HbA1c level was not found to have a significant association with LV diastolic dysfunction in overweight/obese group.

CONCLUSIONS

In patients with type 2 diabetes, correlation between LV diastolic dysfunction and HbA1c was interactively affected by BMI. Glycemic control is beneficial to the heart function in normal body weight patients. For overweight/obese patients, the risk of LV diastolic dysfunction was not determined by the HbA1c level, indicating it may be affected by other confounding factors.