Fernanda Rodrigues de Souza

The Role for Cardiovascular Remodeling in Cardiovascular Outcomes

Purpose of ReviewIschemic and non-ischemic injury to the heart causes deleterious changes in ventricular size, shape, and function. This adverse remodeling is mediated by neurohormonal and hemodynamic alterations and is reflected in non-invasive measures of left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), and left ventricular end-diastolic volume (LVEDV). These measures are closely linked to cardiovascular outcomes and have become key surrogate endpoints for evaluating the therapeutic efficacy of contemporary treatments for heart failure with reduced ejection fraction (HFrEF). In this review, we critically evaluate recent published data (2015–2016) from randomized clinical trials (RCTs) and observational studies of HFrEF therapies to assess the role of ventricular remodeling on outcomes.Recent FindingsThese data highlight the benefits of certain guideline-directed medical therapies (GDMT) such as cardiac resynchronization therapy, surgical revascularization, and mechanical circulatory support on remodeling, while revealing the limitations of other therapies—routine mitral valve repair for patients with moderate ischemic mitral regurgitation and adjuncts to percutaneous coronary intervention in patients with ST elevation myocardial infarction (cyclosporine A and bioabsorbable cardiac matrix). The new angiotensin receptor blocker/neprilysn inhibitor, sacubitril/valsartan, demonstrates convincing improvements in clinical outcomes with a study of remodeling parameters to follow; the new cardiac myosin activator, omecamtiv mecarbil, demonstrates improvement in remodeling parameters without a clear early clinical benefit.SummaryThe concepts and contemporary trials reviewed in this paper reinforce the value of non-invasive measures of ventricular remodeling (LVEF, LVESV, and LVEDV) as important metrics across a range of cardiovascular therapies. Global non-invasive measures of cardiovascular remodeling have roughly paralleled or preceded hard clinical outcomes. Additionally, the capacity for reverse remodeling in HFrEF with GDMT motivates continued research in the fields of implementation science, diagnostic imaging, and gene-based therapeutics.

Short-term and long-term models of doxorubicin-induced cardiomyopathy in rats: A comparison of functional and histopathological changes

OBJECTIVES Doxorubicin (DXR), an anthracyclic antineoplastic agent, is one of the most commonly drug utilized to induce dilated cardiomyopathy (DCM) and heart failure (HF), but the well optimized protocol for cardiomyopathy induction leading to development of cardiac systolic dysfunction is unclear. This study aims to critically compare short-term and long-term DXR injection protocols for the induction of DCM in rats. METHODS Animals were allocated into 3 experimental groups: a ST (short-term DXR injection) group, in which animals received 6 intraperitoneal (i.p.) injections of DXR (2.5mg/kg per dose) over a period of 2 weeks (cumulative dose of 15mg/kg); a LT (long-term DXR injection) group in which animals received weekly i.p. injections of DXR (2mg/kg per dose) over a period of 9 weeks (cumulative dose of 18mg/kg); and a control group in which animals received an appropriate volume of 0.9% saline i.p. All animals were submitted to echocardiography analysis at baseline and after completion treatment. Afterwards, the hearts were collected for conventional light microscopy and collagen quantification. RESULTS Morphological myocardial analysis of both DXR-treated groups showed an identical pattern of swollen and vacuolated cardiomyocytes and disorganization of myofibrils. There was pronounced interstitial fibrosis in both groups of DXR-treated hearts as compared to controls, as assessed by the interstitial collagen volume fraction. There was no difference in interstitial fibrosis between the ST and LT groups. The echocardiography analysis of the LT group showed structural and functional findings compatible with DCM, including increased left ventricular systolic (5.02±0.96mm) and diastolic (7.68±0.96mm) dimensions and reduction of ejection fraction (69.40±8.51%) as compared to the ST group (4.10±0.89mm, 7.32±0.84, and 79.68±7.23%, respectively) and control group (4.07±0.72mm, 7.17±0.68mm and 80.08±4.71%, respectively), ANOVA p<0.01. CONCLUSIONS These results indicate that LT injection of DXR is more effective than ST injection in inducing left ventricular dysfunction and structural cardiac changes resembling those found in dilated cardiomyopathy.

The thyroid hormone receptor β-selective agonist GC-1 does not affect tolerance to exercise in hypothyroid rats

OBJECTIVE Investigate the effect of GC-1 on tolerance to exercise in rats with experimental hypothyroidism. MATERIALS AND METHODS Hypothyroidism was induced with methimazole sodium and perchlorate treatment. Six groups with eight animals were studied: control group (C), hypothyroid group without treatment (HYPO); hypothyroidism treated with physiological doses of tetraiodothyronine (T4) or 10 times higher (10×T4); hypothyroidism treated with equal molar doses of GC-1 (GC-1) or 10 times higher (10×GC-1). After eight weeks, each animal underwent an exercise tolerance test by measuring the time (seconds), in which the rats were swimming with a load attached to their tails without being submerging for more than 10 sec. After the test, the animals were killed, and blood samples were collected for biochemical analysis, and the heart and soleus muscle were removed for weighing and morphometric analysis of the cardiomyocyte. RESULTS Hypothyroidism significantly reduced tolerance to exercise and, treatment with GC-1 1× or T4 in physiological doses recover tolerance test to normal parameters. However, high doses of T4 also decreased tolerance to physical exercise. Conversely, ten times higher doses of GC-1 did not impair tolerance to exercise. Interestingly, hypothyroidism, treated or not with T4 in a physiological range, GC-1 or even high doses of GC-1 (10X) did not change cardiomyocyte diameters and relative weight of the soleus muscle. In contrast, higher doses of T4 significantly increased cardiomyocyte diameter and induced atrophy of the soleus muscle. CONCLUSION Unlike T4, GC-1 in high doses did not modify tolerance to physical exercise in the rats with hypothyroidism.

Hypertrophic response of the Association of Thyroid Hormone and Exercise in the Heart of Rats

Background Cardiac hypertrophy is a component of cardiac remodeling occurring in response to an increase of the activity or functional overload of the heart. Objective Assess hypertrophic response of the association of thyroid hormone and exercise in the rat heart. Methods We used 37 Wistar rats, male, adults were randomly divided into four groups: control, hormone (TH), exercise (E), thyroid hormone and exercise (H + E); the group received daily hormone levothyroxine sodium by gavage at a dose of 20 μg thyroid hormone/100g body weight, the exercise group took swimming five times a week, with additional weight corresponding to 20% of body weight for six weeks; in group H + E were applied simultaneously TH treatment groups and E. The statistics used was analysis of variance, where appropriate, by Tukey test and Pearson correlation test. Results The T4 was greater in groups TH and H + E. The total weight of the heart was greater in patients who received thyroid hormone and left ventricular weight was greater in the TH group. The transverse diameter of cardiomyocytes increased in groups TH, E and H + E. The percentage of collagen was greater in groups E and H + E Correlation analysis between variables showed distinct responses. Conclusion The association of thyroid hormone with high-intensity exercise produced cardiac hypertrophy, and generated a standard hypertrophy not directly correlated to the degree of fibrosis.

Efficacy and safety of pharmacological interventions in metabolic syndrome: protocol for systematic review and network meta-analysis

Introduction: The prevalence of metabolic syndrome (MetS) and MetS-related stroke is set to increase dramatically in coming decades. MetS is a complex disease that includes endothelial dysfunction, insulin resistance, diabetes, hypertension, ectopic obesity, and dyslipidaemia and an increased risk of cardiovascular events.This study aims to fill this gap of research by conducting a Bayesian network meta-analysis to compare major drugs to treat MetS. Methods and analysis: We will search the PubMed, EMBASE, Cochrane Library, Web of Science, Embase, google scholar, clinical trials registry (ClinicalTrials. gov) for unpublished or undergoing research listed in registry platforms. Randomized controlled trials (RCTs) on the drug therapy of MetS with outcome measures including diagnostic criteria of MetS will be included. The quality of included RTCs will be evaluated according to the Cochrane Collaboration’s risk of bias tool. Traditional pairwise meta-analysis and Bayesian network meta-analysis will be conducted to compare the efficacies of antidiabetic drugs. Sensitivity analysis on the sample size of RCTs, meta-regression analysis on the follow-up periods, dosages and baselines of outcome measure, contradiction analysis between pairwise and network meta-analyses, and publication bias analysis, will be performed. Randomized controlled trials (RCTs) on the drug therapy of MetS with outcome measures criteria of MetS diagnostic will be included. The quality of included RTCs will be evaluated according to the Cochrane Collaboration’s risk of bias tool. Traditional pairwise meta-analysis and Bayesian network meta-analysis will be conducted to compare the efficacies of drugs. Sensitivity analysis on the sample size of RCTs, meta-regression analysis on the follow-up periods, dosages and baselines of outcome measure, contradiction analysis between pairwise and network meta-analyses, and publication bias analysis, will be performed. Ethics and dissemination Ethics approval was not required for this study because it was based on published studies. The results and findings of this study will be submitted and published in a scientific peer-reviewed journal. Trial registration number: PROSPERO (CRD42018083468). *Correspondence to: Leonardo Roever, MHS, Federal University of Uberlândia, Department of Clinical Research, Brazil, Email: leonardoroever@hotmail.com