Empagliflozin Increases Cardiac Energy Production in Diabetes: Novel Translational Insights Into the Heart Failure Benefits of SGLT2 Inhibitors

Atrial fibrillation in cancer, anticancer therapies, and underlying mechanisms

Atrial fibrillation (AF) is a common arrhythmic complication in cancer patients and can be exacerbated by traditional cytotoxic and targeted anticancer therapies. Increased incidence of AF in cancer patients is independent of confounding factors, including preexisting myocardial arrhythmogenic substrates, type of cancer, or cancer stage. Mechanistically, AF is characterized by fast unsynchronized atrial contractions with rapid ventricular response, which impairs ventricular filling and results in various symptoms such as fatigue, chest pain, and shortness of breath. Due to increased blood stasis, a consequence of both cancer and AF, concern for stroke increases in this patient population. To compound matters, cardiotoxic anticancer therapies themselves promote AF; thereby exacerbating AF morbidity and mortality in cancer patients. In this review, we examine the relationship between AF, cancer, and cardiotoxic anticancer therapies with a focus on the shared molecular and electrophysiological mechanisms linking these disease processes. We also explore the potential role of sodium-glucose co-transporter 2 inhibitors (SGLT2i) in the management of anticancer-therapy-induced AF.

Beta-adrenergic agonism protects mitochondrial metabolism in the pancreatectomised rat heart

The diabetic heart is characterised by functional, morphological and metabolic alterations predisposing it to contractile failure. Chronic sympathetic activation is a feature of the pathogenesis of heart failure, however the type 1 diabetic heart shows desensitisation to β-adrenergic stimulation. Here, we sought to understand the impact of repeated isoprenaline-mediated β-stimulation upon cardiac mitochondrial respiratory capacity and substrate metabolism in the 90% pancreatectomy (Px) rat model of type 1 diabetes. We hypothesised these hearts would be relatively protected against the metabolic impact of stress-induced cardiomyopathy. We found that individually both Px and isoprenaline suppressed cardiac mitochondrial respiration, but that this was preserved in Px rats receiving isoprenaline. Px and isoprenaline had contrasting effects on cardiac substrate metabolism, with increased reliance upon cardiac fatty acid oxidation capacity and altered ketone metabolism in the hearts of Px rats, but enhanced capacity for glucose uptake and metabolism in isoprenaline-treated rats. Moreover, Px rats were protected against isoprenaline-induced mortality, whilst isoprenaline elevated cGMP and protected myocardial energetic status in Px rat hearts. Our work suggests that adrenergic stimulation may be protective in the type 1 diabetic heart, and underlines the importance of studying pathological features in combination when modeling complex disease in rodents.

Empagliflozin, a sodium-glucose cotransporter inhibitor enhancing mitochondrial action and cardioprotection in metabolic syndrome

Metabolic syndrome (MetS) has a large clinical population nowadays, usually due to excessive energy intake and lack of exercise. During MetS, excess nutrients stress the mitochondria, resulting in relative hypoxia in tissues and organs, even when blood supply is not interrupted or reduced, making mitochondrial dysfunction a central pathogenesis of cardiovascular disease in the MetS. Sodium-glucose cotransporter 2 inhibitors were designed as a hyperglycemic drug that acts on the renal tubules to block sugar reabsorption in primary urine. Recently they have been shown to have anti-inflammatory and other protective effects on cardiomyocytes in MetS, and have also been recommended in the latest heart failure guidelines as a routine therapy. Among these inhibitors, empagliflozin shows better clinical promise due to less influence from glomerular filtration rate. This review focuses on the mitochondrial mechanisms of empagliflozin, which underlie the anti-inflammatory and recover cellular functions in MetS cardiomyocytes, including stabilizing calcium concentration, mediating metabolic reprogramming, maintaining homeostasis of mitochondrial quantity and quality, stable mitochondrial DNA copy number, and repairing damaged mitochondrial DNA.

Sodium glucose cotransporter-2 inhibitors and heart disease: Current perspectives

Sodium glucose cotransporter-2 inhibitors (SGLT-2i) are antidiabetic medications with remarkable cardiovascular (CV) benefits proven by multiple randomised controlled trials and real-world data. These drugs are also useful in the prevention of CV disease (CVD) in patients with diabetes mellitus (DM). Although DM as such is a huge risk factor for CVD, the CV benefits of SGLT-2i are not just because of antidiabetic effects. These molecules have proven beneficial roles in prevention and management of nondiabetic CVD and renal disease as well. There are various molecular mechanisms for the organ protective effects of SGLT-2i which are still being elucidated. Proper understanding of the role of SGLT-2i in prevention and management of CVD is important not only for the cardiologists but also for other specialists caring for various illnesses which can directly or indirectly impact care of heart diseases. This clinical review compiles the current evidence on the rational use of SGLT-2i in clinical practice.

ELUCIDATE Trial: A Single-Center Randomized Controlled Study

BACKGROUND

Dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, is an epochal oral antidiabetic drug that improves cardiorenal outcomes. However, the effect of early dapagliflozin intervention on left ventricular (LV) remodeling in patients with type 2 diabetes free from cardiovascular disease remains unclear.

METHODS AND RESULTS

The ELUCIDATE trial was a prospective, open-label, randomized, active-controlled study that enrolled 76 patients with asymptomatic type 2 diabetes with LV ejection fraction ≥50%, randomized to the dapagliflozin 10 mg/day add-on or standard-of-care group. Speckle-tracking echocardiography-based measurements of the cardiac global longitudinal strain were performed at baseline and 24 weeks after treatment initiation. Patients who received dapagliflozin had a greater reduction in LV dimension (1.68 mm [95% CI, 0.53-2.84]; P=0.005), LV end-systolic volume (5.51 mL [95% CI, 0.86-10.17]; P=0.021), and LV mass index (4.25 g/m2.7 [95% CI, 2.42-6.09]; P<0.0001) compared with standard of care in absolute mean differences. Dapagliflozin add-on therapy led to a significant LV global longitudinal strain increment (0.74% [95% CI, 1.00-0.49]; P<0.0001) and improved LV systolic and early diastolic strain rates (0.27/s [95% CI, 0.17-0.60]; and 0.11/s [95% CI, 0.06-0.16], respectively; both P<0.0001) but not in global circumferential strain. No significant changes were found in insulin resistance, NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels, or other biomarkers at 6 months after the dapagliflozin administration.

CONCLUSIONS

Dapagliflozin add-on therapy could lead to more favorable cardiac remodeling accompanied by enhanced cardiac mechanical function among patients with asymptomatic type 2 diabetes. Our findings provide evidence of the efficacy of dapagliflozin use for the primary prevention of diabetic cardiomyopathy.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03871621.

Cardiovascular Effects of Oral Ketone Ester Treatment in Patients With Heart Failure With Reduced Ejection Fraction: A Randomized, Controlled, Double-Blind Trial

BACKGROUND

Heart failure triggers a shift in myocardial metabolic substrate utilization, favoring the ketone body 3-hydroxybutyrate as energy source. We hypothesized that 14-day treatment with ketone ester (KE) would improve resting and exercise hemodynamics and exercise capacity in patients with heart failure with reduced ejection fraction.

METHODS

In a randomized, double-blind cross-over study, nondiabetic patients with heart failure with reduced ejection fraction received 14-day KE and 14-day isocaloric non-KE comparator regimens of 4 daily doses separated by a 14-day washout period. After each treatment period, participants underwent right heart catheterization, echocardiography, and blood sampling at plasma trough levels and after dosing. Participants underwent an exercise hemodynamic assessment after a second dosing. The primary end point was resting cardiac output (CO). Secondary end points included resting and exercise pulmonary capillary wedge pressure and peak exercise CO and metabolic equivalents.

RESULTS

We included 24 patients with heart failure with reduced ejection fraction (17 men; 65±9 years of age; all White). Resting CO at trough levels was higher after KE compared with isocaloric comparator (5.2±1.1 L/min versus 5.0±1.1 L/min; difference, 0.3 L/min [95% CI, 0.1-0.5), and pulmonary capillary wedge pressure was lower (8±3 mm Hg versus 11±3 mm Hg; difference, -2 mm Hg [95% CI, -4 to -1]). These changes were amplified after KE dosing. Across all exercise intensities, KE treatment was associated with lower mean exercise pulmonary capillary wedge pressure (-3 mm Hg [95% CI, -5 to -1] ) and higher mean CO (0.5 L/min [95% CI, 0.1-0.8]), significantly different at low to moderate steady-state exercise but not at peak. Metabolic equivalents remained similar between treatments. In exploratory analyses, KE treatment was associated with 18% lower NT-proBNP (N-terminal pro-B-type natriuretic peptide; difference, -98 ng/L [95% CI, -185 to -23]), higher left ventricular ejection fraction (37±5 versus 34±5%; P=0.01), and lower left atrial and ventricular volumes.

CONCLUSIONS

KE treatment for 14 days was associated with higher CO at rest and lower filling pressures, cardiac volumes, and NT-proBNP levels compared with isocaloric comparator. These changes persisted during exercise and were achieved on top of optimal medical therapy. Sustained modulation of circulating ketone bodies is a potential treatment principle in patients with heart failure with reduced ejection fraction.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05161650.

Effect of Luseogliflozin on Myocardial Flow Reserve in Patients with Type 2 Diabetes Mellitus (LUCENT-J Study)

INTRODUCTION

In patients with type 2 diabetes (T2D), treatment with sodium-glucose cotransporter-2 (SGLT2) inhibitors has been shown to reduce hospital admission rates for heart failure (HF). However, the multiple mechanisms hypothesized and investigated to explain the cardioprotection of SGLT2 inhibitors are not fully understood.

OBJECTIVES

The effect of luseogliflozin on myocardial flow reserve (MFR) in patients with T2D (LUCENT-J) study aims to examine the effects of SGLT2 inhibitors on myocardial perfusion.

METHODS

The LUCENT-J study is a prospective, single-center, randomized, two-arm, parallel-group, open-label (i.e., the radiology readers are blinded), active-controlled study. A cohort of 40 patients with T2D with no or stable (with no history of myocardial infarction and with or without previous percutaneous coronary intervention) coronary artery disease will be included. Patients will be randomized in a 1:1 ratio to luseogliflozin or control and treated for 24 weeks. The primary outcome is the change in MFR, as measured by 13N-ammonia positron emission tomography/computed tomography, from baseline to 24 weeks after treatment initiation.

PLANNED OUTCOMES

The LUCENT-J study will elucidate the mechanisms of cardioprotection by SGLT2 inhibitors in patients with T2D.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (JRCTs051220016).

Redefining Diabetic Cardiomyopathy: Perturbations in Substrate Metabolism at the Heart of Its Pathology

Cardiovascular disease represents the leading cause of death in people with diabetes, most notably from macrovascular diseases such as myocardial infarction or heart failure. Diabetes also increases the risk of a specific form of cardiomyopathy, referred to as diabetic cardiomyopathy (DbCM), originally defined as ventricular dysfunction in the absence of underlying coronary artery disease and/or hypertension. Herein, we provide an overview on the key mediators of DbCM, with an emphasis on the role for perturbations in cardiac substrate metabolism. We discuss key mechanisms regulating metabolic dysfunction in DbCM, with additional focus on the role of metabolites as signaling molecules within the diabetic heart. Furthermore, we discuss the preclinical approaches to target these perturbations to alleviate DbCM. With several advancements in our understanding, we propose the following as a new definition for, or approach to classify, DbCM: "diastolic dysfunction in the presence of altered myocardial metabolism in a person with diabetes but absence of other known causes of cardiomyopathy and/or hypertension." However, we recognize that no definition can fully explain the complexity of why some individuals with DbCM exhibit diastolic dysfunction, whereas others develop systolic dysfunction. Due to DbCM sharing pathological features with heart failure with preserved ejection fraction (HFpEF), the latter of which is more prevalent in the population with diabetes, it is imperative to determine whether effective management of DbCM decreases HFpEF prevalence.

ARTICLE HIGHLIGHTS

Sodium-glucose linked transporter 2 inhibitors in liver cirrhosis: Beyond their antidiabetic use

Type 2 diabetes mellitus (T2DM) and liver cirrhosis are clinical entities that frequently coexist, but glucose-lowering medication options are limited in cirrhotic patients. Sodium-glucose linked transporter 2 (SGLT2) inhibitors are a class of glucose-lowering medication that act independently of insulin, by causing glycosuria in the proximal convoluted tubule. In this review, we aimed to briefly present the main data and to provide insight into the pathophysiology and potential usefulness of SGLT2 inhibitors in cirrhotic patients with or without T2DM. SGLT2 inhibitors have been proven useful as antidiabetic treatment in patients with metabolic liver disease, with most robust data from patients with metabolic dysfunction-associated steatotic liver disease (MASLD), where they also showed improvement in liver function parameters. Moreover, it has been suggested that SGLT2 inhibitors may have effects beyond their antidiabetic action. Accordingly, they have exhibited cardioprotective effects, expanding their indication in patients with heart failure without T2DM. Since decompensated liver cirrhosis and congestive heart failure share common pathophysiological features, namely renin-angiotensin-aldosterone axis and sympathetic nervous system activation as well as vasopressin secretion, SGLT2 inhibitors could also be beneficial in patients with decompensated cirrhosis, even in the absence of T2DM.

Mitochondrial fatty acid oxidation is the major source of cardiac adenosine triphosphate production in heart failure with preserved ejection fraction

AIMS

Heart failure with preserved ejection fraction (HFpEF) is a prevalent disease worldwide. While it is well established that alterations of cardiac energy metabolism contribute to cardiovascular pathology, the precise source of fuel used by the heart in HFpEF remains unclear. The objective of this study was to define the energy metabolic profile of the heart in HFpEF.

METHODS AND RESULTS

Eight-week-old C57BL/6 male mice were subjected to a '2-Hit' HFpEF protocol [60% high-fat diet (HFD) + 0.5 g/L of Nω-nitro-L-arginine methyl ester]. Echocardiography and pressure-volume loop analysis were used for assessing cardiac function and cardiac haemodynamics, respectively. Isolated working hearts were perfused with radiolabelled energy substrates to directly measure rates of fatty acid oxidation, glucose oxidation, ketone oxidation, and glycolysis. HFpEF mice exhibited increased body weight, glucose intolerance, elevated blood pressure, diastolic dysfunction, and cardiac hypertrophy. In HFpEF hearts, insulin stimulation of glucose oxidation was significantly suppressed. This was paralleled by an increase in fatty acid oxidation rates, while cardiac ketone oxidation and glycolysis rates were comparable with healthy control hearts. The balance between glucose and fatty acid oxidation contributing to overall adenosine triphosphate (ATP) production was disrupted, where HFpEF hearts were more reliant on fatty acid as the major source of fuel for ATP production, compensating for the decrease of ATP originating from glucose oxidation. Additionally, phosphorylated pyruvate dehydrogenase levels decreased in both HFpEF mice and human patient's heart samples.

CONCLUSION

In HFpEF, fatty acid oxidation dominates as the major source of cardiac ATP production at the expense of insulin-stimulated glucose oxidation.

Underlying mechanisms and cardioprotective effects of SGLT2i and GLP-1Ra: insights from cardiovascular magnetic resonance

Originally designed as anti-hyperglycemic drugs, Glucagon-Like Peptide-1 receptor agonists (GLP-1Ra) and Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have demonstrated protective cardiovascular effects, with significant impact on cardiovascular morbidity and mortality. Despite several mechanisms have been proposed, the exact pathophysiology behind these effects is not yet fully understood. Cardiovascular imaging is key for the evaluation of diabetic patients, with an established role from the identification of early subclinical changes to long-term follow up and prognostic assessment. Among the different imaging modalities, CMR may have a key-role being the gold standard for volumes and function assessment and having the unique ability to provide tissue characterization. Novel techniques are also implementing the possibility to evaluate cardiac metabolism through CMR and thereby further increasing the potential role of the modality in this context. Aim of this paper is to provide a comprehensive review of changes in CMR parameters and novel CMR techniques applied in both pre-clinical and clinical studies evaluating the effects of SGLT2i and GLP-1Ra, and their potential role in better understanding the underlying CV mechanisms of these drugs.

Effects of SGLT2 Inhibitors with and without Metformin in High-Risk, Treatment-Naïve Patients with Diabetes

Background: Contemporary evidence supports the cardiovascular and renal benefits of sodium-glucose co-transporter-2 inhibitors (SGLT2is) in patients with diabetes. While metformin has traditionally been recommended as a first-line treatment, its exact role in improving cardiovascular outcomes remains uncertain. This study aims to evaluate the impact of combination therapy with metformin on the cardiovascular and renal outcomes in high-risk, treatment-naïve diabetic patients who have undergone SGLT2i therapy. Methods: Using the National Health Insurance Research Database in Taiwan, a retrospective cohort study was conducted. Treatment-naïve patients with diabetes and established atherosclerotic cardiovascular disease (ASCVD) undertaking SGLT2i therapy from 1 January 2016 to 31 December 2021 were included. Patients were categorized based on the concomitant use of metformin. Propensity score matching was employed to minimize confounding factors. The primary outcome was major adverse cardiovascular events (MACEs), with secondary outcomes including cardiovascular death, hospitalization for heart failure, and renal outcomes. Results: In total, 10,151 treatment-naïve diabetic patients with ASCVD were identified, with 2570 in the only SGLT2i therapy group and 7581 in the SGLT2i plus metformin group. In total, 2262 pairs were analyzed after propensity score adjustment. The risk of MACEs (36.6 vs. 42.1 events per 1000 person-years; hazard ratio 0.87, 95% confidence interval 0.70-1.09) and other outcomes did not significantly differ between the two treatment groups. Conclusions: In high-risk, treatment-naïve diabetic patients, initiating SGLT2i therapy alone or in combination with metformin resulted in comparable cardiovascular and renal outcomes. These findings suggest that metformin might not be mandatory as a first-line treatment for achieving cardiovascular benefits in such patients.

Acute antiarrhythmic effects of SGLT2 inhibitors-dapagliflozin lowers the excitability of atrial cardiomyocytes

In recent years, SGLT2 inhibitors have become an integral part of heart failure therapy, and several mechanisms contributing to cardiorenal protection have been identified. In this study, we place special emphasis on the atria and investigate acute electrophysiological effects of dapagliflozin to assess the antiarrhythmic potential of SGLT2 inhibitors. Direct electrophysiological effects of dapagliflozin were investigated in patch clamp experiments on isolated atrial cardiomyocytes. Acute treatment with elevated-dose dapagliflozin caused a significant reduction of the action potential inducibility, the amplitude and maximum upstroke velocity. The inhibitory effects were reproduced in human induced pluripotent stem cell-derived cardiomyocytes, and were more pronounced in atrial compared to ventricular cells. Hypothesizing that dapagliflozin directly affects the depolarization phase of atrial action potentials, we examined fast inward sodium currents in human atrial cardiomyocytes and found a significant decrease of peak sodium current densities by dapagliflozin, accompanied by a moderate inhibition of the transient outward potassium current. Translating these findings into a porcine large animal model, acute elevated-dose dapagliflozin treatment caused an atrial-dominant reduction of myocardial conduction velocity in vivo. This could be utilized for both, acute cardioversion of paroxysmal atrial fibrillation episodes and rhythm control of persistent atrial fibrillation. In this study, we show that dapagliflozin alters the excitability of atrial cardiomyocytes by direct inhibition of peak sodium currents. In vivo, dapagliflozin exerts antiarrhythmic effects, revealing a potential new additional role of SGLT2 inhibitors in the treatment of atrial arrhythmias.

Empagliflozin improves mitochondrial dysfunction in diabetic cardiomyopathy by modulating ketone body metabolism and oxidative stress

Ketone bodies are considered as an alternative energy source for diabetic cardiomyopathy (DCM) and can improve the energy supply of the heart muscle, suggesting that it may be an important area of research and development as a therapeutic target for DCM. Cumulative cardiovascular trials have shown that sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce cardiovascular events in diabetic populations. Whether SGLT2 inhibitors improve DCM by enhancing ketone body metabolism remains and whether they help prevent oxidative damage remains to be clarified. Here, we present the combined results of nine GSE datasets for diabetic cardiomyopathy (GSE215979, GSE161931, GSE145294, GSE161052, GSE173384, GSE123975, GSE161827, GSE210612, and GSE5606). We found significant up-regulated gene 3-hydroxymethylglutaryl CoA synthetase 2 (HMGCS2) and down-regulated gene 3-hydroxybutyrate dehydrogenase (BDH1) and 3-oxoacid CoA-transferase1 (OXCT1), respectively. Based on the analysis of the constructed protein interaction network, it was found that HMGCS2 was in the core position of the interaction network. In addition, Gene ontology (GO) enrichment analysis mainly focused on redox process, acyl-CoA metabolic process, catalytic activity, redox enzyme activity and mitochondria. The activity of HMGCS2 in DCM heart was increased, while the expression of ketolysis enzymes BDH1 and OXCT1 was inhibited. In vivo, Empagliflozin (Emp) treated DCM group significantly decreased ventricular weight, myocardial cell cross-sectional area, and myocardial fibrosis. In addition, Emp further promoted the activity of BDH1 and OXCT1, increased the utilization of ketone bodies, further promoted the activity of HMGCS2 in DCM, and increased the synthesis of ketone bodies, prevented mitochondrial breakage and dysfunction, increased myocardial ATP to provide sufficient energy, inhibited oxidative stress and apoptosis of cardiac cells ex vivo, and improved the myocardial dysfunction of DCM. Emp can improve mitochondrial dysfunction in diabetic cardiomyopathy by regulating ketone body metabolism and oxidative stress. These findings provide a theoretical basis for evaluating Emp as a treatment for DCM.

The Safety and Efficacy of Sodium-Glucose Cotransporter-2 Inhibitors for Patients with Sarcopenia or Frailty: Double Edged Sword?

Sodium-glucose cotransporter-2 inhibitors (SGLT-2is) show cardiovascular protective effects, regardless of the patient's history of diabetes mellitus (DM). SGLT2is suppressed cardiovascular adverse events in patients with type 2 DM, and furthermore, SGLT-2is reduced the risk of worsening heart failure (HF) events or cardiovascular death in patients with HF. Along with these research findings, SGLT-2is are recommended for patients with HF in the latest guidelines. Despite these benefits, the concern surrounding the increasing risk of body weight loss and other adverse events has not yet been resolved, especially for patients with sarcopenia or frailty. The DAPA-HF and DELIVER trials consistently showed the efficacy and safety of SGLT-2i for HF patients with frailty. However, the Rockwood frailty index that derived from a cumulative deficit model was employed for frailty assessment in these trials, which might not be suitable for the evaluation of physical frailty or sarcopenia alone. There is no fixed consensus on which evaluation tool to use or its cutoff value for the diagnosis and assessment of frailty in HF patients, or which patients can receive SGLT-2i safely. In this review, we summarize the methodology of frailty assessment and discuss the efficacy and safety of SGLT-2i for HF patients with sarcopenia or frailty.

Metabolic Flexibility of the Heart: The Role of Fatty Acid Metabolism in Health, Heart Failure, and Cardiometabolic Diseases

This comprehensive review explores the critical role of fatty acid (FA) metabolism in cardiac diseases, particularly heart failure (HF), and the implications for therapeutic strategies. The heart's reliance on ATP, primarily sourced from mitochondrial oxidative metabolism, underscores the significance of metabolic flexibility, with fatty acid oxidation (FAO) being a dominant source. In HF, metabolic shifts occur with an altered FA uptake and FAO, impacting mitochondrial function and contributing to disease progression. Conditions like obesity and diabetes also lead to metabolic disturbances, resulting in cardiomyopathy marked by an over-reliance on FAO, mitochondrial dysfunction, and lipotoxicity. Therapeutic approaches targeting FA metabolism in cardiac diseases have evolved, focusing on inhibiting or stimulating FAO to optimize cardiac energetics. Strategies include using CPT1A inhibitors, using PPARα agonists, and enhancing mitochondrial biogenesis and function. However, the effectiveness varies, reflecting the complexity of metabolic remodeling in HF. Hence, treatment strategies should be individualized, considering that cardiac energy metabolism is intricate and tightly regulated. The therapeutic aim is to optimize overall metabolic function, recognizing the pivotal role of FAs and the need for further research to develop effective therapies, with promising new approaches targeting mitochondrial oxidative metabolism and FAO that improve cardiac function.

Animal models of heart failure with preserved ejection fraction (HFpEF): from metabolic pathobiology to drug discovery

Heart failure (HF) with preserved ejection fraction (HFpEF) is currently a preeminent challenge for cardiovascular medicine. It has a poor prognosis, increasing mortality, and is escalating in prevalence worldwide. Despite accounting for over 50% of all HF patients, the mechanistic underpinnings driving HFpEF are poorly understood, thus impeding the discovery and development of mechanism-based therapies. HFpEF is a disease syndrome driven by diverse comorbidities, including hypertension, diabetes and obesity, pulmonary hypertension, aging, and atrial fibrillation. There is a lack of high-fidelity animal models that faithfully recapitulate the HFpEF phenotype, owing primarily to the disease heterogeneity, which has hampered our understanding of the complex pathophysiology of HFpEF. This review provides an updated overview of the currently available animal models of HFpEF and discusses their characteristics from the perspective of energy metabolism. Interventional strategies for efficiently utilizing energy substrates in preclinical HFpEF models are also discussed.

Protecting cardiomyocytes from hypoxia-reoxygenation injury, empaglifozin and liraglutide alone or in combination?

OBJECTIVES

Empagliflozin, a sodium-dependent glucose co-transporter 2 (SGLT2) inhibitor, and liraglutide, a GLP-1 receptor (GLP-1R) agonist, are commonly recognized for their cardiovascular benefits in individuals with type 2 diabetes (T2D). In prior studies, we have demonstrated that both drugs, alone or in combination, were able to protect cardiomyocytes from injury induced by diabetes. Mechanistic investigations also suggested that the cardioprotective effect may be independent of diabetes In this study, we utilized a hypoxia-reoxygenation (H/R) model to investigate the cardiovascular benefits of SGLT2 inhibitor empagliflozin and GLP-1 receptor (GLP-1R) agonist liraglutide, both alone and in combination, in the absence of T2D. Our hypothesis was that empagliflozin and liraglutide, either individually or in combination, would demonstrate cardioprotective properties against H/R-induced injury, with an additive and/or synergistic effect anticipated from combination therapy.

METHODS

In this study, the cardiac muscle cell line, HL-1 cells, were treated with vehicle, empagliflozin, liraglutide, or a combination of the two drugs. The cells were then subjected to a hypoxia-reoxygenation (H/R) protocol, consisting of 1 h of hypoxia followed by 24 h of reoxygenation. The effects of the treatments on cytotoxicity, oxidative stress, endothelial nitric oxide synthase (eNOS) activity, phospho-protein kinase C (PKC) beta and phospho-eNOS (Thr495) expression were subsequently evaluated at the end of the treatments.

RESULTS

We found that H/R increased cytotoxicity and reduces eNOS activity, empagliflozin, liraglutide or combination treatment attenuated some or all of these effects with the combination therapy showing the greatest improvement.

CONCLUSIONS

Empagliflozin, liraglutide or combination of these two have cardioprotective effect regardless of diabetes. Cardioprotective effects of SGLT2 inhibitor and GLP-1R agonist is additive and synergistic.

Anti-Inflammation and Anti-Oxidation: The Key to Unlocking the Cardiovascular Potential of SGLT2 Inhibitors and GLP1 Receptor Agonists

Type 2 diabetes mellitus (T2DM) is a prevalent and complex metabolic disorder associated with various complications, including cardiovascular diseases. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP1-RA) have emerged as novel therapeutic agents for T2DM, primarily aiming to reduce blood glucose levels. However, recent investigations have unveiled their multifaceted effects, extending beyond their glucose-lowering effect. SGLT2i operate by inhibiting the SGLT2 receptor in the kidneys, facilitating the excretion of glucose through urine, leading to reduced blood glucose levels, while GLP1-RA mimic the action of the GLP1 hormone, stimulating glucose-dependent insulin secretion from pancreatic islets. Both SGLT2i and GLP1-RA have shown remarkable benefits in reducing major cardiovascular events in patients with and without T2DM. This comprehensive review explores the expanding horizons of SGLT2i and GLP1-RA in improving cardiovascular health. It delves into the latest research, highlighting the effects of these drugs on heart physiology and metabolism. By elucidating their diverse mechanisms of action and emerging evidence, this review aims to recapitulate the potential of SGLT2i and GLP1-RA as therapeutic options for cardiovascular health beyond their traditional role in managing T2DM.

Empagliflozin improves cardiac energetics during ischaemia/reperfusion by directly increasing cardiac ketone utilization

AIMS

Empagliflozin (EMPA), a potent inhibitor of the renal sodium-glucose cotransporter 2 and an effective treatment for Type 2 diabetes, has been shown to have cardioprotective effects, independent of improved glycaemic control. Several non-canonical mechanisms have been proposed to explain these cardiac effects, including increasing circulating ketone supply to the heart. This study aims to test whether EMPA directly alters cardiac ketone metabolism independent of supply.

METHODS AND RESULTS

The direct effects of EMPA on cardiac function and metabolomics were investigated in Langendorff rat heart perfused with buffer containing 5 mM glucose, 4 mM β-hydroxybutyrate (βHb) and 0.4 mM intralipid, subject to low flow ischaemia/reperfusion. Cardiac energetics were monitored in situ using 31P NMR spectroscopy. Steady-state 13C labelling was performed by switching 12C substrates for 13C1 glucose or 13C4 βHb and 13C incorporation into metabolites determined using 2D 1H-13C HSQC NMR spectroscopy. EMPA treatment improved left ventricular-developed pressure during ischaemia and reperfusion compared to vehicle-treated hearts. In EMPA-treated hearts, total adenosine triphosphate (ATP) and phosphocreatine (PCr) levels, and Gibbs free energy for ATP hydrolysis were significantly higher during ischaemia and reperfusion. EMPA treatment did not alter the incorporation of 13C from glucose into glycolytic products lactate or alanine neither during ischaemia nor reperfusion. In ischaemia, EMPA led to a decrease in 13C1 glucose incorporation and a concurrent increase in 13C4 βHb incorporation into tricarboxylic acid (TCA) cycle intermediates succinate, citrate, and glutamate. During reperfusion, the concentration of metabolites originating from 13C1 glucose was similar to vehicle but those originating from 13C4 βHb remained elevated in EMPA-treated hearts.

CONCLUSION

Our findings indicate that EMPA causes a switch in metabolism away from glucose oxidation towards increased ketone utilization in the rat heart, thereby improving function and energetics both during ischaemia and recovery during reperfusion. This preference of ketone utilization over glucose was observed under conditions of constant supply of substrate, suggesting that EMPA acts directly by modulating cardiac substrate preference, independent of substrate availability. The mechanisms underlying our findings are currently unknown, warranting further study.

Dapagliflozin protects against chronic heart failure in mice by inhibiting macrophage-mediated inflammation, independent of SGLT2

The specific mechanism of sodium-glucose cotransporter 2 (SGLT2) inhibitor in heart failure (HF) needs to be elucidated. In this study, we use SGLT2-global-knockout (KO) mice to assess the mechanism of SGLT2 inhibitor on HF. Dapagliflozin ameliorates both myocardial infarction (MI)- and transverse aortic constriction (TAC)-induced HF. Global SGLT2 deficiency does not exert protection against adverse remodeling in both MI- and TAC-induced HF models. Dapagliflozin blurs MI- and TAC-induced HF phenotypes in SGLT2-KO mice. Dapagliflozin causes major changes in cardiac fibrosis and inflammation. Based on single-cell RNA sequencing, dapagliflozin causes significant differences in the gene expression profile of macrophages and fibroblasts. Moreover, dapagliflozin directly inhibits macrophage inflammation, thereby suppressing cardiac fibroblasts activation. The cardio-protection of dapagliflozin is blurred in mice treated with a C-C chemokine receptor type 2 antagonist. Taken together, the protective effects of dapagliflozin against HF are independent of SGLT2, and macrophage inhibition is the main target of dapagliflozin against HF.

Sodium-glucose cotransporter-2 inhibitors improve clinical outcomes in patients with type 2 diabetes mellitus undergoing anthracycline-containing chemotherapy: an emulated target trial using nationwide cohort data in South Korea

Novel hypoglycemic agents, sodium-glucose cotransporter 2 inhibitors (SGLT2i), have shown protective effects against anthracycline (AC)-induced cardiotoxicity and exhibit partial anticancer effects in animal models. However, clinical evidence for this is scarce. This study aimed to evaluate whether SGLT2i improve the clinical outcomes of patients with type 2 diabetes mellitus (T2DM) undergoing AC-containing chemotherapy. A total of 81,572 patients who underwent AC chemotherapy between 2014 and 2021 were recruited from a nationwide Korean cohort. Patients were classified into three groups: patients with T2DM taking SGLT2i (n = 780) and other hypoglycemic agents excluding SGLT2i (non-SGLT2i; n = 3,455) during AC chemotherapy, and the non-DM group (n = 77,337). The clinical outcome was a composite of heart failure hospitalization, acute myocardial infarction, ischemic stroke, and death. After propensity score matching, 779 SGLT2i users were compared with 7800 non-DM patients and 2,337 non-SGLT2i users. The SGLT2i group had better composite outcomes compared with the non-DM group (adjusted hazard ratio [HR] = 0.35, 95% confidence interval [95% CI] = 0.25-0.51) and compared with the non-SGLT2i group (adjusted HR = 0.47, 95% CI = 0.32-0.69). In conclusion, SGLT2i may contribute to improving clinical outcomes in patients with T2DM undergoing AC-containing chemotherapy, through an emulated target trial using Korean nationwide cohort data.

The changes of cardiac energy metabolism with sodium-glucose transporter 2 inhibitor therapy

Background/aims

To investigate the specific effects of s odium-glucose transporter 2 inhibitor (SGLT2i) on cardiac energy metabolism.

Methods

A systematic literature search was conducted in eight databases. The retrieved studies were screened according to the inclusion and exclusion criteria, and relevant information was extracted according to the purpose of the study. Two researchers independently screened the studies, extracted information, and assessed article quality.

Results

The results of the 34 included studies (including 10 clinical and 24 animal studies) showed that SGLT2i inhibited cardiac glucose uptake and glycolysis, but promoted fatty acid (FA) metabolism in most disease states. SGLT2i upregulated ketone metabolism, improved the structure and functions of myocardial mitochondria, alleviated oxidative stress of cardiomyocytes in all literatures. SGLT2i increased cardiac glucose oxidation in diabetes mellitus (DM) and cardiac FA metabolism in heart failure (HF). However, the regulatory effects of SGLT2i on cardiac FA metabolism in DM and cardiac glucose oxidation in HF varied with disease types, stages, and intervention duration of SGLT2i.

Conclusion

SGLT2i improved the efficiency of cardiac energy production by regulating FA, glucose and ketone metabolism, improving mitochondria structure and functions, and decreasing oxidative stress of cardiomyocytes under pathological conditions. Thus, SGLT2i is deemed to exert a benign regulatory effect on cardiac metabolic disorders in various diseases.

Systematic review registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023484295).

Effects of canagliflozin on cardiac remodeling and hemodynamic parameters in patients with type 2 diabetes mellitus

Sodium-glucose cotransporter type 2 (SGLT2) inhibitors have demonstrated to reduce cardiovascular risk in patients with type 2 diabetes mellitus (T2DM) in large trials independent of glycemic control. The mechanisms of this cardioprotective property remain uncertain. Evidence suggests positive hemodynamic changes and favorable cardiac remodeling contributing to the clinical outcomes but results were conflicting. We aim to investigate the potential impact on hemodynamic parameters, cardiac structure and functions. This prospective observational study included T2DM patients receiving canagliflozin 100 mg per day in addition to their antidiabetic treatment. We analyzed hemodynamic parameters assessed by echocardiographic measurements and impedance cardiography (ICG) to evaluate systolic and diastolic functions from baseline to 24 weeks after treatment. A total of 47 patients (25 males and 22 females) averaging 64.6 ± 10.9 years had a significant reduction in HbA1c, body weight, and systolic blood pressure. Hematocrit increased significantly, while NT-proBNP remained unchanged. E/e', left atrium (LA) volume, and LA stiffness were reduced, while left ventricle (LV) global longitudinal strain (GLS) and LA strain rates increased at 24 weeks by conventional and speckle tracking echocardiography. LV mass and ejection fraction showed no differences. ICG suggested significant improvement in hemodynamic parameters with increased stroke volume index and cardiac output index and decreased systemic vascular resistance index at 12 and 24 weeks. Canagliflozin improved hemodynamic parameters and had a favorable impact on LA and LV reverse remodeling. These changes may explain the beneficial effect on cardiovascular outcomes in large clinical trials.

Metabolic mechanisms in physiological and pathological cardiac hypertrophy: new paradigms and challenges

Cardiac metabolism is vital for heart function. Given that cardiac contraction requires a continuous supply of ATP in large quantities, the role of fuel metabolism in the heart has been mostly considered from the perspective of energy production. However, the consequence of metabolic remodelling in the failing heart is not limited to a compromised energy supply. The rewired metabolic network generates metabolites that can directly regulate signalling cascades, protein function, gene transcription and epigenetic modifications, thereby affecting the overall stress response of the heart. In addition, metabolic changes in both cardiomyocytes and non-cardiomyocytes contribute to the development of cardiac pathologies. In this Review, we first summarize how energy metabolism is altered in cardiac hypertrophy and heart failure of different aetiologies, followed by a discussion of emerging concepts in cardiac metabolic remodelling, that is, the non-energy-generating function of metabolism. We highlight challenges and open questions in these areas and finish with a brief perspective on how mechanistic research can be translated into therapies for heart failure.

Treatment and practical considerations of diabetic kidney disease

Diabetic kidney disease (DKD) is a complication of diabetes that can lead to kidney failure. Over the years, several drugs have been developed to combat this disease. In the early 90s, angiotensin blockade (ACEi and ARBs) was introduced, which revolutionized the treatment of DKD. In recent years, newer drugs such as sodium-glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 (GLP-1) receptor agonists, endothelin antagonists, and mineralocorticoid receptor antagonists (MRA) have shown great promise in reducing albuminuria and protecting the kidneys. These drugs are being used in combination with lifestyle modifications, patient education, and risk factor modification to effectively manage DKD. In this review, we will explore the latest pharmacological options, their efficacy, and their potential to revolutionize the management of this debilitating disease.

Sodium Glucose Co-Transporter 2 Inhibitors and the Cardiovascular System: Current Knowledge and Future Expectations

Diabetic cardiomyopathy is a well-recognized clinical entity and reflects a complex relationship between metabolic substrates and myocardial function. Sodium glucose co-transporter 2 (SGLT2) inhibitors are antidiabetic agents that are found to exert multiple cardioprotective effects. Large clinical trials showed their beneficial effects on patients with heart failure, reducing the rates of rehospitalizations and improving kidney function. The aim of this review is to summarize the latest evidence in the literature regarding the multiple effects of SGLT2 inhibitors on patients across the spectrum of cardiovascular diseases.

The Ketogenic Effect of SGLT-2 Inhibitors-Beneficial or Harmful?

Sodium-glucose cotransporter-2 (SGLT-2) inhibitors, also called gliflozins or flozins, are a class of drugs that have been increasingly used in the management of type 2 diabetes mellitus (T2DM) due to their glucose-lowering, cardiovascular (CV), and renal positive effects. However, recent studies suggest that SGLT-2 inhibitors might also have a ketogenic effect, increasing ketone body production. While this can be beneficial for some patients, it may also result in several potential unfavorable effects, such as decreased bone mineral density, infections, and ketoacidosis, among others. Due to the intricate and multifaceted impact caused by SGLT-2 inhibitors, this initially anti-diabetic class of medications has been effectively used to treat both patients with chronic kidney disease (CKD) and those with heart failure (HF). Additionally, their therapeutic potential appears to extend beyond the currently investigated conditions. The objective of this review article is to present a thorough summary of the latest research on the mechanism of action of SGLT-2 inhibitors, their ketogenesis, and their potential synergy with the ketogenic diet for managing diabetes. The article particularly discusses the benefits and risks of combining SGLT-2 inhibitors with the ketogenic diet and their clinical applications and compares them with other anti-diabetic agents in terms of ketogenic effects. It also explores future directions regarding the ketogenic effects of SGLT-2 inhibitors.

Protective effect of canagliflozin on post-resuscitation myocardial function in a rat model of cardiac arrest

BACKGROUND

Currently, most patients with cardiac arrest (CA) show reversible myocardial dysfunction, hemodynamic instability, systemic inflammation and other pathophysiological state in early stage of resuscitation, some patients may eventually progress to multiple organ failure. There is evidence that heart failure is the terminal stage in the development of various cardiovascular diseases. Although the cardio-protective effect of canagliflozin (CANA) has been confirmed in large clinical studies and recommended in domestic and international heart failure-related guidelines, the effectiveness of CANA after resuscitation remains unclear. In this study, we constructed a modified CA/CPR rat model to investigate whether CANA administered on post-resuscitation improves myocardial function.

METHODS

Twenty-fourth healthy male Sprague-Dawley rats were randomized into four groups: (1) Sham + placebo group, (2) Sham + CANA group, (3) CPR + placebo group, and (4) CPR + CANA group. Ventricular fibrillation was induced by transcutaneous electrical stimulation on epicardium. After 6 min untreated ventricular fibrillation, chest compressions was initiated. The rats were received an injection of placebo or canagliflozin (3 ug/kg) randomly 15 min after restore of spontaneous circulation (ROSC). Electrocardiogram (ECG) and blood pressure were continuously detected in each group throughout the experiment. The rats were killed 6 h after ROSC to collected the arterial serum and myocardial tissue. Myocardial injury was estimated with concentrations of inflammatory factors, oxidative stress indexes and, apoptosis index, myocardial injury markers, echocardiography and myocardial pathological slices.

RESULTS

After resuscitation, mean arterial pressure (MAP) were significantly increased after cardiopulmonary resuscitation in CANA group rats when compared with placebo group. Heart rate, body lactate returned and left ventricular ejection fraction (LVEF) to normal levels in a shorter time and the myocardial injury was obviously attenuated in CPR + CANA group. Inflammatory factors (IL-6, TNF-α) and oxidative stress indexes (MAD, SOD, CAT) were dramatically decreased with the administration of CANA. The expression of apoptosis index (BAX, caspase-3) were higher in CPR + placebo group and the expression of anti-apoptosis index (Bcl-2) was lower (P < 0.05).

CONCLUSIONS

The administration of CANA effectively reduces myocardial ischaemia/reperfusion (I/R) injury after cardiac arrest and cardiopulmonary resuscitation (CPR), and the underlying mechanism may be related to anti-inflammation, oxidative stress and apoptosis.

Sodium-Glucose Cotransporter 2 Inhibitors Among Heart Failure With Mildly Reduced and Preserved Ejection Fraction

OBJECTIVE

Results from large placebo-controlled randomized trials in patients with heart failure with mid-range ejection fraction (HFmrEF) and HF with preserved EF (HFpEF) have become available recently. This article discusses results of these clinical trials.

DATA SOURCES

Peer-reviewed articles were identified from MEDLINE (1966 to December 31, 2022) using search terms dapagliflozin, empagliflozin, SGLT-2Is, HFmrEF, and HFpEF.

STUDY SELECTION AND DATA EXTRACTION

Eight completed, pertinent clinical trials were included.

DATA SYNTHESIS

EMPEROR-Preserved, and DELIVER demonstrated that empagliflozin and dapagliflozin reduce CV death and heart failure hospitalization (HHF) in patients with HFmrEF and HFpEF, with/without diabetes when added to a standard heart failure (HF) regimen. The benefit is primarily due to reduction in HHF. Additional data from post hoc analyses of trials of dapagliflozin, ertugliflozin, and sotagliflozin suggest that these benefits may be a class effect. Benefits appear greatest in patients with left ventricular ejection fraction 41% up to about 65%.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

While many pharmacologic treatments have been proven to reduce mortality and improve cardiovascular (CV) outcomes in people with HFmrEF and HF with reduced EF (HFrEF), there are few therapy which improve CV outcome in people with HFpEF. SGLT-2I become one of the first class of pharmacologic agent that can be used to reduce HHF and CV mortality.

CONCLUSION

Studies showed that empagliflozin and dapagliflozin reduce the combined risk of CV death or HHF in patients with HFmrEF and HFpEF when added to a standard HF regimen. Given that benefit has now been demonstrated across the spectrum of HF, SGLT-2Is should be considered one of the standard HF pharmacotherapy.

Searching for Effective Treatments in HFpEF: Implications for Modeling the Disease in Rodents

BACKGROUND

While the prevalence of heart failure with preserved ejection fraction (HFpEF) has increased over the last two decades, there still remains a lack of effective treatment. A key therapeutic challenge is posed by the absence of animal models that accurately replicate the complexities of HFpEF. The present review summarizes the effects of a wide spectrum of therapeutic agents on HF.

METHODS

Two online databases were searched for studies; in total, 194 experimental protocols were analyzed following the PRISMA protocol.

RESULTS

A diverse range of models has been proposed for studying therapeutic interventions for HFpEF, with most being based on pressure overload and systemic hypertension. They have been used to evaluate more than 150 different substances including ARNIs, ARBs, HMGR inhibitors, SGLT-2 inhibitors and incretins. Existing preclinical studies have primarily focused on LV diastolic performance, and this has been significantly improved by a wide spectrum of candidate therapeutic agents. Few experiments have investigated the normalization of pulmonary congestion, exercise capacity, animal mortality, or certain molecular hallmarks of heart disease.

CONCLUSIONS

The development of comprehensive preclinical HFpEF models, with multi-organ system phenotyping and physiologic stress-based functional testing, is needed for more successful translation of preclinical research to clinical trials.

The safety of sodium-glucose co-transporter 2 inhibitors in patients with left ventricular assist device - a single center experience

AIMS

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are used increasingly for patients with heart failure or chronic kidney disease to improve cardiac and renal outcomes. The use of these medications in patients with left ventricular assist devices (LVAD) is still limited and lacks evidence regarding the safety profile. In this study, we aimed to report our experience in treating 20 patients, supported by LVAD, with SGLT2 inhibitors.

METHODS

We studied the safety profile of SGLT2 inhibitors (dapagliflozin and empagliflozin) in 20 patients (mean age 64.7 ± 12.2 years, 75% male) supported by LVAD as destination therapy. All patients have diabetes mellitus and were prescribed SGLT2 inhibitors for glycemic control.

RESULTS

SGLT2 inhibitors were well tolerated with no major adverse events. Few suction events were reported in three patients without the need for pump speed adjustment. There was no change in mean arterial pressure (71.1 ± 5.6 vs. 70.1 ± 4.8 mmHg, P  = 0.063). Modest decline in renal function was observed in six patients within the first weeks after drug initiation. There were no events of diabetic ketoacidosis or limb amputation.

CONCLUSION

SGLT2 inhibitors are safe in patients with LVAD and may potentially improve cardiovascular and renal outcomes in this special population.

Reno- and cardioprotective molecular mechanisms of SGLT2 inhibitors beyond glycemic control: from bedside to bench

Large placebo-controlled clinical trials have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) delay the deterioration of renal function and reduce cardiovascular events in a glucose-independent manner, thereby ultimately reducing mortality in patients with chronic kidney disease (CKD) and/or heart failure. These existing clinical data stimulated preclinical studies aiming to understand the observed clinical effects. In animal models, it was shown that the beneficial effect of SGLT2i on the tubuloglomerular feedback (TGF) improves glomerular pressure and reduces tubular workload by improving renal hemodynamics, which appears to be dependent on salt intake. High salt intake might blunt the SGLT2i effects on the TGF. Beyond the salt-dependent effects of SGLT2i on renal hemodynamics, SGLT2i inhibited several key aspects of macrophage-mediated renal inflammation and fibrosis, including inhibiting the differentiation of monocytes to macrophages, promoting the polarization of macrophages from a proinflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and suppressing the activation of inflammasomes and major proinflammatory factors. As macrophages are also important cells mediating atherosclerosis and myocardial remodeling after injury, the inhibitory effects of SGLT2i on macrophage differentiation and inflammatory responses may also play a role in stabilizing atherosclerotic plaques and ameliorating myocardial inflammation and fibrosis. Recent studies suggest that SGLT2i may also act directly on the Na+/H+ exchanger and Late-INa in cardiomyocytes thus reducing Na+ and Ca2+ overload-mediated myocardial damage. In addition, the renal-cardioprotective mechanisms of SGLT2i include systemic effects on the sympathetic nervous system, blood volume, salt excretion, and energy metabolism.

How Does It Work? Unraveling the Mysteries by Which Empagliflozin Helps Diabetic and Non-diabetic Patients With Heart Failure

In patients with heart failure, empagliflozin offers significant cardiovascular benefits. However, its exact mode of action is unknown. Understanding the way by which empagliflozin works in heart failure may uncover additional therapeutic targets or identify other classes of drugs that may be useful to clinicians and patients. This literature review aims to unravel the mysteries by which empagliflozin reduces cardiovascular death, cardiovascular events, and heart failure hospitalization in diabetic and non-diabetic patients. Three researchers conducted the data collection. We incorporated research that used human models, animal models, patients with diabetes, and patients without diabetes. Pathology, pathophysiology, metabolism, physiology, empagliflozin, heart failure, and cardiovascular were the search terms used to probe the mesh database on PubMed. This study showed that the mechanisms by which empagliflozin could lead to positive clinical outcomes in heart failure (HF) are as follows: down-regulation of the mammalian target of rapamycin complex 1 signaling (mTORC), decreasing sarcoplasmic reticulum calcium loss, increasing cytosolic calcium loss, inducing electrolyte-free osmotic diuresis, improving fuel efficiency, and protecting the endothelial glycocalyx. These findings were inconsistent, with no generally accepted hypotheses within the scientific community. Hence we conclude that further research is required to determine the function of Empagliflozin in heart failure and the degree to which the aforementioned mechanisms of action contribute to cardiac protection.

Metabolic Drivers and Rescuers of Heart Failure

Cardiac hypertrophy and heart failure involve a number of metabolic alterations. Human genetic mutations and murine genetic deficiency models of metabolic enzymes or transporters largely suggest that these alterations in metabolism are maladaptive and contribute to the cardiac remodeling and dysfunction. Here, we discuss insights into metabolic alterations identified in cardiac hypertrophy and failure, as well as dietary and pharmacologic therapies that counteract these metabolic alterations and have been shown to significantly improve heart failure.

Exploring the Cardiovascular Benefits of Sodium-Glucose Cotransporter-2 (SGLT2) Inhibitors: Expanding Horizons Beyond Diabetes Management

Globally, cardiovascular disease (CVD) continues to be the primary cause of morbidity and mortality. The risk of cardiovascular disease is markedly increased in individuals with type 2 diabetes mellitus (T2DM), making managing cardiovascular health a top priority. Initially developed for their glucose-lowering properties, sodium-glucose cotransporter 2 (SGLT2) inhibitors have emerged as a transformative class of pharmaceuticals with profound cardiovascular benefits that extend far beyond glycemic control. One of the most striking findings is the substantial reduction in major adverse cardiovascular events (MACE), including myocardial infarction, stroke, and cardiovascular mortality, observed in clinical trials evaluating SGLT2 inhibitors. These extraordinary cardioprotective effects are demonstrated by landmark trials such as EMPA-REG OUTCOME, CANVAS, and DECLARE-TIMI 58, which are discussed in detail. In addition, SGLT2 inhibitors have demonstrated positive outcomes in heart failure (HF) with reduced ejection fraction, which has led to their incorporation into HF treatment guidelines. SGLT2 inhibitors offer renoprotection by delaying the progression of diabetic kidney disease, reducing albuminuria, preserving glomerular filtration rates, and their immediate cardiovascular benefits. We investigate the potential mechanisms underlying these renal benefits, focusing on the role of hemodynamic alterations and intraglomerular pressure reduction. In addition, SGLT2 inhibitors have a distinct diuretic effect that can contribute to volume reduction and symptom alleviation in patients with heart failure (HF). This diuretic action, distinct from conventional diuretics, warrants additional research to optimize their use in T2DM and HF patients. The risk of euglycemic diabetic ketoacidosis, genital mycobacterial infections, and bone fractures are also discussed. Understanding these issues is essential for making educated clinical decisions. In conclusion, SGLT2 inhibitors have transcended their initial function as anti-diabetic agents to become essential components of cardiovascular and renal protection strategies in T2DM patients. Their diverse benefits, which include cardioprotection, renoprotection, and the potential for HF management, highlight their potential to transform cardiovascular medicine. Optimizing the use of SGLT2 inhibitors in clinical practice bears the promise of improved cardiovascular outcomes for patients with T2DM and beyond as we navigate this changing landscape.

New Therapeutics for Heart Failure: Focusing on cGMP Signaling

Current drugs for treating heart failure (HF), for example, angiotensin II receptor blockers and β-blockers, possess specific target molecules involved in the regulation of the cardiac circulatory system. However, most clinically approved drugs are effective in the treatment of HF with reduced ejection fraction (HFrEF). Novel drug classes, including angiotensin receptor blocker/neprilysin inhibitor (ARNI), sodium-glucose co-transporter-2 (SGLT2) inhibitor, hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker, soluble guanylyl cyclase (sGC) stimulator/activator, and cardiac myosin activator, have recently been introduced for HF intervention based on their proposed novel mechanisms. SGLT2 inhibitors have been shown to be effective not only for HFrEF but also for HF with preserved ejection fraction (HFpEF). In the myocardium, excess cyclic adenosine monophosphate (cAMP) stimulation has detrimental effects on HFrEF, whereas cyclic guanosine monophosphate (cGMP) signaling inhibits cAMP-mediated responses. Thus, molecules participating in cGMP signaling are promising targets of novel drugs for HF. In this review, we summarize molecular pathways of cGMP signaling and clinical trials of emerging drug classes targeting cGMP signaling in the treatment of HF.

SGLT2 inhibitors: role in protective reprogramming of cardiac nutrient transport and metabolism

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce heart failure events by direct action on the failing heart that is independent of changes in renal tubular function. In the failing heart, nutrient transport into cardiomyocytes is increased, but nutrient utilization is impaired, leading to deficient ATP production and the cytosolic accumulation of deleterious glucose and lipid by-products. These by-products trigger downregulation of cytoprotective nutrient-deprivation pathways, thereby promoting cellular stress and undermining cellular survival. SGLT2 inhibitors restore cellular homeostasis through three complementary mechanisms: they might bind directly to nutrient-deprivation and nutrient-surplus sensors to promote their cytoprotective actions; they can increase the synthesis of ATP by promoting mitochondrial health (mediated by increasing autophagic flux) and potentially by alleviating the cytosolic deficiency in ferrous iron; and they might directly inhibit glucose transporter type 1, thereby diminishing the cytosolic accumulation of toxic metabolic by-products and promoting the oxidation of long-chain fatty acids. The increase in autophagic flux mediated by SGLT2 inhibitors also promotes the clearance of harmful glucose and lipid by-products and the disposal of dysfunctional mitochondria, allowing for mitochondrial renewal through mitochondrial biogenesis. This Review describes the orchestrated interplay between nutrient transport and metabolism and nutrient-deprivation and nutrient-surplus signalling, to explain how SGLT2 inhibitors reverse the profound nutrient, metabolic and cellular abnormalities observed in heart failure, thereby restoring the myocardium to a healthy molecular and cellular phenotype.

Left ventricular mass predicts cardiac reverse remodelling in patients treated with empagliflozin

BACKGROUND

The cardiovascular (CV) benefits of sodium-glucose transport protein 2 inhibitors have been attributed, in part, to cardiac reverse remodelling. The EMPA-HEART CardioLink-6 study reported that sodium-glucose cotransporter-2 inhibition for 6 months with empagliflozin was associated with a significant reduction in left ventricular mass indexed to body surface area (LVMi). In this sub-analysis, we evaluated whether baseline LVMi may influence how empagliflozin affects cardiac reverse remodelling.

METHODS

A total of 97 patients with type 2 diabetes and coronary artery disease were randomized to empagliflozin (10 mg/d) or matching placebo for 6 months. The study cohort was divided into those whose baseline LVMi was ≤ 60 g/m² and those who had a baseline LVMi > 60 g/m². Subgroup comparisons were conducted using a linear regression model adjusted for baseline values (ANCOVA) that included an interaction term between LVMi subgroup and treatment.

RESULTS

Baseline LVMi was 53.3 g/m² (49.2-57.2) and 69.7 g/m² (64.2-76.1) for those with baseline ≤ 60 g/m² (n = 54) and LVMi > 60 g/m² (n = 43) respectively. The adjusted difference of LVMi regression between those randomized to empagliflozin and placebo were - 0.46 g/m² (95% CI: -3.44, 2.52, p = 0.76) in the baseline LVMi ≤ 60 g/m² subgroup and - 7.26 g/m² (95% CI: -11.40, -3.12, p = 0.0011) in the baseline LVMi > 60 g/m² subgroup (p-for-interaction = 0.007). No significant associations were found between baseline LVMi and 6-month change in LV end systolic volume-indexed (p-for-interaction = 0.086), LV end diastolic volume-indexed (p-for-interaction = 0.34), or LV ejection fraction (p-for-interaction = 0.15).

CONCLUSIONS

Patients with higher LVMi at baseline experienced greater LVM regression with empagliflozin.

Predicting and preventing heart failure in type 2 diabetes

The burden of heart failure among people with type 2 diabetes is increasing globally. People with comorbid type 2 diabetes and heart failure often have worse outcomes than those with only one of these conditions-eg, higher hospitalisation and mortality rates. Therefore, it is essential to implement optimal heart failure prevention strategies for people with type 2 diabetes. A detailed understanding of the pathophysiology underlying the occurrence of heart failure in type 2 diabetes can aid clinicians in identifying relevant risk factors and lead to early interventions that can help prevent heart failure. In this Review, we discuss the pathophysiology and risk factors of heart failure in type 2 diabetes. We also review the risk assessment tools for predicting heart failure incidence in people with type 2 diabetes as well as the data from clinical trials that have assessed the efficacy of lifestyle and pharmacological interventions. Finally, we discuss the potential challenges in implementing new management approaches and offer pragmatic recommendations to help overcome these challenges.

Assessment of Cardiac Energy Metabolism, Function, and Physiology in Patients With Heart Failure Taking Empagliflozin: The Randomized, Controlled EMPA-VISION Trial

BACKGROUND

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have emerged as a paramount treatment for patients with heart failure (HF), irrespective of underlying reduced or preserved ejection fraction. However, a definite cardiac mechanism of action remains elusive. Derangements in myocardial energy metabolism are detectable in all HF phenotypes, and it was proposed that SGLT2i may improve energy production. The authors aimed to investigate whether treatment with empagliflozin leads to changes in myocardial energetics, serum metabolomics, and cardiorespiratory fitness.

METHODS

EMPA-VISION (Assessment of Cardiac Energy Metabolism, Function and Physiology in Patients With Heart Failure Taking Empagliflozin) is a prospective, randomized, double-blind, placebo-controlled, mechanistic trial that enrolled 72 symptomatic patients with chronic HF with reduced ejection fraction (HFrEF; n=36; left ventricular ejection fraction ≤40%; New York Heart Association class ≥II; NT-proBNP [N-terminal pro-B-type natriuretic peptide] ≥125 pg/mL) and HF with preserved ejection fraction (HFpEF; n=36; left ventricular ejection fraction ≥50%; New York Heart Association class ≥II; NT-proBNP ≥125 pg/mL). Patients were stratified into respective cohorts (HFrEF versus HFpEF) and randomly assigned to empagliflozin (10 mg; n=35: 17 HFrEF and 18 HFpEF) or placebo (n=37: 19 HFrEF and 18 HFpEF) once daily for 12 weeks. The primary end point was a change in the cardiac phosphocreatine:ATP ratio (PCr/ATP) from baseline to week 12, determined by phosphorus magnetic resonance spectroscopy at rest and during peak dobutamine stress (65% of age-maximum heart rate). Mass spectrometry on a targeted set of 19 metabolites was performed at baseline and after treatment. Other exploratory end points were investigated.

RESULTS

Empagliflozin treatment did not change cardiac energetics (ie, PCr/ATP) at rest in HFrEF (adjusted mean treatment difference [empagliflozin - placebo], -0.25 [95% CI, -0.58 to 0.09]; P=0.14) or HFpEF (adjusted mean treatment difference, -0.16 [95% CI, -0.60 to 0.29]; P=0.47]. Likewise, there were no changes in PCr/ATP during dobutamine stress in HFrEF (adjusted mean treatment difference, -0.13 [95% CI, -0.35 to 0.09]; P=0.23) or HFpEF (adjusted mean treatment difference, -0.22 [95% CI, -0.66 to 0.23]; P=0.32). No changes in serum metabolomics or levels of circulating ketone bodies were observed.

CONCLUSIONS

In patients with either HFrEF or HFpEF, treatment with 10 mg of empagliflozin once daily for 12 weeks did not improve cardiac energetics or change circulating serum metabolites associated with energy metabolism when compared with placebo. Based on our results, it is unlikely that enhancing cardiac energy metabolism mediates the beneficial effects of SGLT2i in HF.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03332212.

Sodium-Glucose Co-Transporter 2 Inhibitors in Heart Failure-Current Evidence in Special Populations

Sodium-glucose co-transporter 2 (SGLT2) inhibitors, originally used for diabetes mellitus, are gaining more popularity for other indications, owing to their positive cardiovascular and renal effects. SGLT2 inhibitors reduce heart failure (HF) hospitalization and improve cardiovascular outcomes in patients with type 2 diabetes. Later, SGLT2 inhibitors were evaluated in patients with HF with reduced ejection fraction (HFREF) and had beneficial effects independent of the presence of diabetes. Recently, reductions in cardiovascular outcomes were also observed in patients with HF with preserved ejection fraction (HFPEF). SGLT2 inhibitors also reduced renal outcomes in patients with chronic kidney disease. Overall, these drugs have an excellent safety profile with a negligible risk of genitourinary tract infections and ketoacidosis. In this review, we discuss the current data on SGLT2 inhibitors in special populations, including patients with acute myocardial infarction, acute HF, right ventricular (RV) failure, left ventricular assist device (LVAD), and type 1 diabetes. We also discuss the potential mechanisms behind the cardiovascular benefits of these medications.

Medical Treatment in Heart Failure with Reduced Ejection Fraction: A Proposed Algorithm Based on the Patient's Electrolytes and Congestion Status

In heart failure (HF) with reduced ejection fraction (HFrEF), four classes of drugs (β-blockers, angiotensin-converting enzyme inhibitors/angiotensin receptor neprilysin inhibitors, mineralocorticoid receptor antagonists, and the most recent Sodium-Glucose Co-Transporters 2 Inhibitors) have demonstrated positive results in randomized controlled trials (RCTs). Nevertheless, the latest RCTs are not proper for comparison since they were carried out at various times with dissimilar background therapies and the patients enrolled did not have the same characteristics. The difficulty of extrapolating from these trials and proposing a common framework appropriate for all cases is thus obvious. Despite the fact that these four agents are now the fundamental pillars of HFrEF treatment, the built-up algorithm of initiation and titration is a matter of debate. Electrolyte disturbances are common in HFrEF patients and can be attributed to several factors, such as the use of diuretics, renal impairment, and neurohormonal activation. We have identified several HFrEF phenotypes according to their sodium (Na+) and potassium (K+) status in a "real world" setting and suggest an algorithm on how to introduce the most appropriate drug and set up therapy based on the patients' electrolytes and the existence of congestion.

Metabolic Syndrome and Cardiac Remodeling Due to Mitochondrial Oxidative Stress Involving Gliflozins and Sirtuins

PURPOSE OF REVIEW

To address the mechanistic pathways focusing on mitochondria dysfunction, oxidative stress, sirtuins imbalance, and other contributors in patient with metabolic syndrome and cardiovascular disease. Sodium glucose co-transporter type 2 (SGLT-2) inhibitors deeply influence these mechanisms. Recent randomized clinical trials have shown impressive results in improving cardiac function and reducing cardiovascular and renal events. These unexpected results generate the need to deepen our understanding of the molecular mechanisms able to generate these effects to help explain such significant clinical outcomes.

RECENT FINDINGS

Cardiovascular disease is highly prevalent among individuals with metabolic syndrome and diabetes. Furthermore, mitochondrial dysfunction is a principal player in its development and persistence, including the consequent cardiac remodeling and events. Another central protagonist is the renin-angiotensin system; the high angiotensin II (Ang II) activity fuel oxidative stress and local inflammatory responses. Additionally, sirtuins decline plays a pivotal role in the process; they enhance oxidative stress by regulating adaptive responses to the cellular environment and interacting with Ang II in many circumstances, including cardiac and vascular remodeling, inflammation, and fibrosis. Fasting and lower mitochondrial energy generation are conditions that substantially reduce most of the mentioned cardiometabolic syndrome disarrangements. In addition, it increases sirtuins levels, and adenosine monophosphate-activated protein kinase (AMPK) signaling stimulates hypoxia-inducible factor-1β (HIF-1 beta) and favors ketosis. All these effects favor autophagy and mitophagy, clean the cardiac cells with damaged organelles, and reduce oxidative stress and inflammatory response, giving cardiac tissue protection. In this sense, SGLT-2 inhibitors enhance the level of at least four sirtuins, some located in the mitochondria. Moreover, late evidence shows that SLGT-2 inhibitors mimic this protective process, improving mitochondria function, oxidative stress, and inflammation. Considering the previously described protection at the cardiovascular level is necessary to go deeper in the knowledge of the effects of SGLT-2 inhibitors on the mitochondria function. Various of the protective effects these drugs clearly had shown in the trials, and we briefly describe it could depend on sirtuins enhance activity, oxidative stress reduction, inflammatory process attenuation, less interstitial fibrosis, and a consequent better cardiac function. This information could encourage investigating new therapeutic strategies for metabolic syndrome, diabetes, heart and renal failure, and other diseases.

Insights into SGLT2 inhibitor treatment of diabetic cardiomyopathy: focus on the mechanisms

Among the complications of diabetes, cardiovascular events and cardiac insufficiency are considered two of the most important causes of death. Experimental and clinical evidence supports the effectiveness of SGLT2i for improving cardiac dysfunction. SGLT2i treatment benefits metabolism, microcirculation, mitochondrial function, fibrosis, oxidative stress, endoplasmic reticulum stress, programmed cell death, autophagy, and the intestinal flora, which are involved in diabetic cardiomyopathy. This review summarizes the current knowledge of the mechanisms of SGLT2i for the treatment of diabetic cardiomyopathy.

Mapping the metabolic reprogramming induced by sodium-glucose cotransporter 2 inhibition

Diabetes is associated with increased risk for kidney disease, heart failure, and mortality. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) prevent these adverse outcomes; however, the mechanisms involved are not clear. We generated a roadmap of the metabolic alterations that occur in different organs in diabetes and in response to SGLT2i. In vivo metabolic labeling with 13C-glucose in normoglycemic and diabetic mice treated with or without dapagliflozin, followed by metabolomics and metabolic flux analyses, showed that, in diabetes, glycolysis and glucose oxidation are impaired in the kidney, liver, and heart. Treatment with dapagliflozin failed to rescue glycolysis. SGLT2 inhibition increased glucose oxidation in all organs; in the kidney, this was associated with modulation of the redox state. Diabetes was associated with altered methionine cycle metabolism, evident by decreased betaine and methionine levels, whereas treatment with SGLT2i increased hepatic betaine along with decreased homocysteine levels. mTORC1 activity was inhibited by SGLT2i along with stimulation of AMPK in both normoglycemic and diabetic animals, possibly explaining the protective effects against kidney, liver, and heart diseases. Collectively, our findings suggest that SGLT2i induces metabolic reprogramming orchestrated by AMPK-mTORC1 signaling with common and distinct effects in various tissues, with implications for diabetes and aging.

Research progress on the effects of novel hypoglycemic drugs in diabetes combined with myocardial ischemia/reperfusion injury

Acute myocardial infarction (AMI) reperfusion is associated with ischemia/reperfusion (I/R) injury, which leads to enlarged myocardial infarction size, poor healing of the infarcted myocardium, and poor left ventricular remodeling, thus increasing the risk of major adverse cardiovascular events (MACEs). Diabetes increases myocardial susceptibility to I/R injury, decreases myocardial responsiveness to cardioprotective strategies, exacerbates myocardial I/R injury, and expands the infarct size of AMI, thereby increasing the incidence of malignant arrhythmias and heart failure. Currently, evidence regarding pharmacological interventions for diabetes combined with AMI and I/R injury is lacking. Traditional hypoglycemic drugs have a limited role in the prevention and treatment of diabetes combined with I/R injury. Current evidence suggests that novel hypoglycemic drugs may exert a preventive effect on diabetes combined with myocardial I/R injury, especially glucagon-like peptide-1 receptor agonists (GLP-1 RA) and sodium-dependent glucose transporter protein 2 inhibitors (SGLT2i), which may increase coronary blood flow, reduce acute thrombosis, attenuate I/R injury, decrease myocardial infarction size, inhibit structural and functional remodeling of the ischemic heart, improve cardiac function, and reduce the occurrence of MACEs of diabetes patients combined with AMI via mechanisms such as reduction of inflammatory response, inhibition of oxidative stress, and improvement of vascular endothelial function. This paper will systematically elaborate the protective role and molecular mechanisms of GLP-1 RA and SGLT2i in diabetes combined with myocardial I/R injury, aiming to provide clinical assistance.

Manganese-Enhanced Magnetic Resonance Imaging of the Heart

Manganese-based contrast media were the first in vivo paramagnetic agents to be used in magnetic resonance imaging (MRI). The uniqueness of manganese lies in its biological function as a calcium channel analog, thus behaving as an intracellular contrast agent. Manganese ions are taken up by voltage-gated calcium channels in viable tissues, such as the liver, pancreas, kidneys, and heart, in response to active calcium-dependent cellular processes. Manganese-enhanced magnetic resonance imaging (MEMRI) has therefore been used as a surrogate marker for cellular calcium handling and interest in its potential clinical applications has recently re-emerged, especially in relation to assessing cellular viability and myocardial function. Calcium homeostasis is central to myocardial contraction and dysfunction of myocardial calcium handling is present in various cardiac pathologies. Recent studies have demonstrated that MEMRI can detect the presence of abnormal myocardial calcium handling in patients with myocardial infarction, providing clear demarcation between the infarcted and viable myocardium. Furthermore, it can provide more subtle assessments of abnormal myocardial calcium handling in patients with cardiomyopathies and being excluded from areas of nonviable cardiomyocytes and severe fibrosis. As such, MEMRI offers exciting potential to improve cardiac diagnoses and provide a noninvasive measure of myocardial function and contractility. This could be an invaluable tool for the assessment of both ischemic and nonischemic cardiomyopathies as well as providing a measure of functional myocardial recovery, an accurate prediction of disease progression and a method of monitoring treatment response. EVIDENCE LEVEL: 5: TECHNICAL EFFICACY: STAGE 5.

Ketones and the Heart: Metabolic Principles and Therapeutic Implications

The ketone bodies beta-hydroxybutyrate and acetoacetate are hepatically produced metabolites catabolized in extrahepatic organs. Ketone bodies are a critical cardiac fuel and have diverse roles in the regulation of cellular processes such as metabolism, inflammation, and cellular crosstalk in multiple organs that mediate disease. This review focuses on the role of cardiac ketone metabolism in health and disease with an emphasis on the therapeutic potential of ketosis as a treatment for heart failure (HF). Cardiac metabolic reprogramming, characterized by diminished mitochondrial oxidative metabolism, contributes to cardiac dysfunction and pathologic remodeling during the development of HF. Growing evidence supports an adaptive role for ketone metabolism in HF to promote normal cardiac function and attenuate disease progression. Enhanced cardiac ketone utilization during HF is mediated by increased availability due to systemic ketosis and a cardiac autonomous upregulation of ketolytic enzymes. Therapeutic strategies designed to restore high-capacity fuel metabolism in the heart show promise to address fuel metabolic deficits that underpin the progression of HF. However, the mechanisms involved in the beneficial effects of ketone bodies in HF have yet to be defined and represent important future lines of inquiry. In addition to use as an energy substrate for cardiac mitochondrial oxidation, ketone bodies modulate myocardial utilization of glucose and fatty acids, two vital energy substrates that regulate cardiac function and hypertrophy. The salutary effects of ketone bodies during HF may also include extra-cardiac roles in modulating immune responses, reducing fibrosis, and promoting angiogenesis and vasodilation. Additional pleotropic signaling properties of beta-hydroxybutyrate and AcAc are discussed including epigenetic regulation and protection against oxidative stress. Evidence for the benefit and feasibility of therapeutic ketosis is examined in preclinical and clinical studies. Finally, ongoing clinical trials are reviewed for perspective on translation of ketone therapeutics for the treatment of HF.