Laura Petraglia

Impact of Diabetes on Cardiac Sympathetic Innervation in Patients With Heart Failure: A 123I meta-iodobenzylguanidine (123I MIBG) scintigraphic study

OBJECTIVE Impaired parasympathetic and sympathetic nervous system activity have been demonstrated in patients with diabetes mellitus (DM) and correlated with worse prognosis. Few data are available on the effect of DM on cardiac neuropathy in heart failure (HF). The aim of the current study was to assess cardiac sympathetic activity in HF patients with and without DM. RESEARCH DESIGN AND METHODS Patients with severe HF (n = 75), with (n = 37) and without DM (n = 38), and 14 diabetic patients with normal cardiac function underwent 123I meta-iodobenzylguanidine scintigraphy from which early and late heart-to-mediastinum (H/M) ratios were calculated. Clinical, echocardiographic, and biochemical data were measured. RESULTS DM compared with non-DM patients showed significantly lower early (1.65 ± 0.21 vs. 1.75 ± 0.21; P < 0.05) and late H/M ratios (1.46 ± 0.22 vs. 1.58 ± 0.24; P < 0.03). Early and late H/M were significantly higher in DM patients without HF (2.22 ± 0.35 and 1.99 ± 0.24, respectively) than HF patients with (P < 0.0001) and without (P < 0.0001) DM. In HF patients, an inverse correlation between early or late H/M ratio and hemoglobin A1c (HbA1c) (Pearson = −0.473, P = 0.001; Pearson = −0.382, P = 0.001, respectively) was observed. In DM, in multivariate analysis, HbA1c and ejection fraction remained significant predictors of early H/M; HbA1c remained the only significant predictor of late H/M. No correlation between early or late H/M and HbA1c was found in non-DM patients. CONCLUSIONS Diabetic patients with HF show lower cardiac sympathetic activity than HF patients not having DM or than DM patients with a similar degree of autonomic dysfunction not having HF. HbA1c correlated with the degree of reduction in cardiac sympathetic activity.

Changes of Natriuretic Peptides Predict Hospital Admissions in Patients With Chronic Heart Failure: A Meta-Analysis

OBJECTIVES The goal of this study was to explore the association between changes in B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) plasma levels and risk of hospital admission for heart failure (HF) worsening in patients with chronic HF. BACKGROUND The relationship between BNP and NT-proBNP plasma levels and risk of cardiovascular events in patients with chronic HF has been previously demonstrated. However, it is unclear whether changes in BNP and NT-proBNP levels predict morbidity in patients with chronic HF. METHODS The MEDLINE, Cochrane, ISI Web of Science, and SCOPUS databases were searched for papers about HF treatment up to August 2013. Randomized trials enrolling patients with systolic HF, assessing BNP and/or NT-proBNP at baseline and at end of follow-up, and reporting hospital stay for HF were included in the analysis. Meta-regression analysis was performed to test the relationship between BNP and NT-proBNP changes and the clinical endpoint. Sensitivity analysis was performed to assess the influence of baseline variables on results. Eggers linear regression was used to assess publication bias. RESULTS Nineteen trials enrolling 12,891 participants were included. The median follow-up was 9.5 months (interquartile range: 6 to 18 months), and 22% of patients were women. Active treatments significantly reduced the risk of hospital stay for HF worsening. In meta-regression analysis, changes in BNP and NT-proBNP were significantly associated with risk of hospital stay for HF worsening. Results were confirmed by using sensitivity analysis. No publication bias was detected. CONCLUSIONS In patients with HF, reduction of BNP or NT-proBNP levels was associated with reduced risk of hospital stay for HF worsening.

Autonomic dysfunction in Alzheimer's disease: tools for assessment and review of the literature.

Autonomic dysfunction is very common in patients with dementia, and its presence might also help in differential diagnosis among dementia subtypes. Various central nervous system structures affected in Alzheimers disease are also implicated in autonomic nervous system regulation, and it has been hypothesized that the deficit in central cholinergic function observed in Alzheimers disease could likely lead to autonomic dysfunction. Several feasible tests can be used in clinical practice for the assessment of parasympathetic and sympathetic functions, especially in terms of cardiovascular autonomic modulation. In this review, we describe the different tests available and the evidence from the literature which indicate a definite presence of autonomic dysfunction in dementia at various degrees. Importantly, the recognition of dysautonomia, besides possibly being an early marker of dementia, would help prevent the disabling complications which increase the risk of morbidity, institutionalization, and mortality in these individuals.

Effects of exercise training on cardiovascular adrenergic system

In heart failure (HF), exercise has been shown to modulate cardiac sympathetic hyperactivation which is one of the earliest features of neurohormonal derangement in this syndrome and correlates with adverse outcome. An important molecular alteration related to chronic sympathetic overstimulation in HF is represented by cardiac β-adrenergic receptor (β-AR) dysfunction. It has been demonstrated that exercise reverses β-AR dysfunction by restoring cardiac receptor membrane density and G-protein-dependent adenylyl cyclase activation. In particular, several evidence indicate that exercise reduces levels of cardiac G-protein coupled receptor kinase-2 (GRK2) which is known to be involved in both β1-AR and β2-AR dysregulation in HF. Similar alterations of β-AR system have been described also in the senescent heart. It has also been demonstrated that exercise training restores adrenal GRK2/α-2AR/catecholamine (CA) production axis. At vascular level, exercise shows a therapeutic effect on age-related impairment of vascular reactivity to adrenergic stimulation and restores β-AR-dependent vasodilatation by increasing vascular β-AR responsiveness and reducing endothelial GRK2 activity. Sympathetic nervous system overdrive is thought to account for >50% of all cases of hypertension and a lack of balance between parasympathetic and sympathetic modulation has been observed in hypertensive subjects. Non-pharmacological, lifestyle interventions have been associated with reductions in SNS overactivity and blood pressure in hypertension. Several evidence have highlighted the blood pressure lowering effects of aerobic endurance exercise in patients with hypertension and the significant reduction in sympathetic neural activity has been reported as one of the main mechanisms explaining the favorable effects of exercise on blood pressure control.

Increased Epicardial Adipose Tissue Volume Correlates With Cardiac Sympathetic Denervation in Patients With Heart Failure

RATIONALE It has been reported that epicardial adipose tissue (EAT) may affect myocardial autonomic function. OBJECTIVE The aim of this study was to explore the relationship between EAT and cardiac sympathetic nerve activity in patients with heart failure. METHODS AND RESULTS In 110 patients with systolic heart failure, we evaluated the correlation between echocardiographic EAT thickness and cardiac adrenergic nerve activity assessed by (123)I-metaiodobenzylguanidine ((123)I-MIBG). The predictive value of EAT thickness on cardiac sympathetic denervation ((123)I-MIBG early and late heart:mediastinum ratio and single-photon emission computed tomography total defect score) was tested in a multivariate analysis. Furthermore, catecholamine levels, catecholamine biosynthetic enzymes, and sympathetic nerve fibers were measured in EAT and subcutaneous adipose tissue biopsies obtained from patients with heart failure who underwent cardiac surgery. EAT thickness correlated with (123)I-MIBG early and late heart:mediastinum ratio and single-photon emission computed tomography total defect score, but not with left ventricular ejection fraction. Moreover, EAT resulted as an independent predictor of (123)I-MIBG early and late heart:mediastinum ratio and single-photon emission computed tomography total defect score and showed a significant additive predictive value on (123)I-MIBG planar and single-photon emission computed tomography results over demographic and clinical data. Although no differences were found in sympathetic innervation between EAT and subcutaneous adipose tissue, EAT showed an enhanced adrenergic activity demonstrated by the increased catecholamine levels and expression of catecholamine biosynthetic enzymes. CONCLUSIONS This study provides the first evidence of a direct correlation between increased EAT thickness and cardiac sympathetic denervation in heart failure.

Impact of diabetes mellitus on lymphocyte GRK2 protein levels in patients with heart failure

Diabetes mellitus (DM) is associated with impaired prognosis in patients with heart failure (HF), but pathogenic mechanisms are unclear. In the failing heart, elevated β‐adrenergic receptor (β‐AR) activation by catecholamines causes G‐protein‐coupled receptor kinase‐2 (GRK2) upregulation which is responsible for β‐AR signalling dysfunction. Importantly, GRK2 expression, measured in peripheral lymphocytes of HF patients, correlates with levels of this kinase in the failing myocardium reflecting the loss of hemodynamic function. Moreover, HF‐related GRK2 protein overexpression promotes insulin resistance by interfering with insulin signalling. The aim of this study was to assess lymphocyte GRK2 protein levels in HF patients with and without DM.

Long-Term Caloric Restriction Improves Cardiac Function, Remodeling, Adrenergic Responsiveness, and Sympathetic Innervation in a Model of Postischemic Heart Failure

Background: Caloric restriction (CR) has been described to have cardioprotective effects and improve functional outcomes in animal models and humans. Chronic ischemic heart failure (HF) is associated with reduced cardiac sympathetic innervation, dysfunctional &bgr;-adrenergic receptor signaling, and decreased cardiac inotropic reserve. We tested the effects of a long-term CR diet, started late after myocardial infarction on cardiac function, sympathetic innervation, and &bgr;-adrenergic receptor responsiveness in a rat model of postischemic HF. Methods and Results: Adult male rats were randomly assigned to myocardial infarction or sham operation and 4 weeks later were further randomized to a 1-year CR or normal diet. One year of CR resulted in a significant reduction in body weight, heart weight, and heart weight/tibia length ratio when compared with normal diet in HF groups. At the end of the study period, echocardiography and histology revealed that HF animals under the CR diet had ameliorated left ventricular remodeling compared with HF rats fed with normal diet. Invasive hemodynamic showed a significant improvement of cardiac inotropic reserve in CR HF rats compared with HF-normal diet animals. Importantly, CR dietary regimen was associated with a significant increase of cardiac sympathetic innervation and with normalized cardiac &bgr;-adrenergic receptor levels in HF rats when compared with HF rats on the standard diet. Conclusions: We demonstrate, for the first time, that chronic CR, when started after HF established, can ameliorate cardiac dysfunction and improve inotropic reserve. At the molecular level, we find that chronic CR diet significantly improves sympathetic cardiac innervation and &bgr;-adrenergic receptor levels in failing myocardium.

Neuro-hormonal effects of physical activity in the elderly

Thanks to diagnostic and therapeutic advances, the elderly population is continuously increasing in the western countries. Accordingly, the prevalence of most chronic age-related diseases will increase considerably in the next decades, thus it will be necessary to implement effective preventive measures to face this epidemiological challenge. Among those, physical activity exerts a crucial role, since it has been proven to reduce the risk of cardiovascular diseases, diabetes, obesity, cognitive impairment and cancer. The favorable effects of exercise on cardiovascular homeostasis can be at least in part ascribed to the modulation of the neuro-hormonal systems implicated in cardiovascular pathophysiology. In the elderly, exercise has been shown to affect catecholamine secretion and biosynthesis, to positively modulate the renin-angiotensin-aldosterone system and to reduce the levels of plasma brain natriuretic peptides. Moreover, drugs modulating the neuro-hormonal systems may favorably affect physical capacity in the elderly. Thus, efforts should be made to actually make physical activity become part of the therapeutic tools in the elderly.

Antidiabetic Drugs in Alzheimer’s Disease: Mechanisms of Action and Future Perspectives

Diabetes mellitus (DM) and Alzheimers disease (AD) are two highly prevalent conditions in the elderly population and major public health burden. In the past decades, a pathophysiological link between DM and AD has emerged and central nervous system insulin resistance might play a significant role as a common mechanism; however, other factors such as inflammation and oxidative stress seem to contribute to the shared pathophysiological link. Both preclinical and clinical studies have evaluated the possible neuroprotective mechanisms of different classes of antidiabetic medications in AD, with some promising results. Here, we review the evidence on the mechanisms of action of antidiabetic drugs and their potential use in AD.

Insulin resistance is associated with impaired cardiac sympathetic innervation in patients with heart failure

AIMS Insulin resistance (IR) represents, at the same time, cause and consequence of heart failure (HF) and affects prognosis in HF patients, but pathophysiological mechanisms remain unclear. Hyperinsulinemia, which characterizes IR, enhances sympathetic drive, and it can be hypothesized that IR is associated with impaired cardiac sympathetic innervation in HF. Yet, this hypothesis has never been investigated. Aim of the present observational study was to assess the relationship between IR and cardiac sympathetic innervation in non-diabetic HF patients. METHODS AND RESULTS One hundred and fifteen patients (87% males; 65 ± 11.3 years) with severe-to-moderate HF (ejection fraction 32.5 ± 9.1%) underwent iodine-123 meta-iodobenzylguanidine ((123)I-MIBG) myocardial scintigraphy to assess sympathetic innervation and Homeostasis Model Assessment Insulin Resistance (HOMA-IR) evaluation to determine the presence of IR. From (123)I-MIBG imaging, early and late heart to mediastinum (H/M) ratios and washout rate were calculated. Seventy-two (63%) patients showed IR and 43 (37%) were non-IR. Early [1.68 (IQR 1.53-1.85) vs. 1.79 (IQR 1.66-1.95); P = 0.05] and late H/M ratio [1.50 (IQR 1.35-1.69) vs. 1.65 (IQR 1.40-1.85); P = 0.020] were significantly reduced in IR compared with non-IR patients. Early and late H/M ratio showed significant inverse correlation with fasting insulinemia and HOMA-IR. CONCLUSION Cardiac sympathetic innervation is more impaired in patients with IR and HF compared with matched non-IR patients. These findings shed light on the relationship among IR, HF, and cardiac sympathetic nervous system. Additional studies are needed to clarify the pathogenetic relationship between IR and HF.