Fenofibrate and Heart Failure Outcomes in Patients With Type 2 Diabetes: Analysis From ACCORD

Metabolism and bioenergetics in the pathophysiology of organ fibrosis

Fibrosis is the tissue scarring characterized by excess deposition of extracellular matrix (ECM) proteins, mainly collagens. A fibrotic response can take place in any tissue of the body and is the result of an imbalanced reaction to inflammation and wound healing. Metabolism has emerged as a major driver of fibrotic diseases. While glycolytic shifts appear to be a key metabolic switch in activated stromal ECM-producing cells, several other cell types such as immune cells, whose functions are intricately connected to their metabolic characteristics, form a complex network of pro-fibrotic cellular crosstalk. This review purports to clarify shared and particular cellular responses and mechanisms across organs and etiologies. We discuss the impact of the cell-type specific metabolic reprogramming in fibrotic diseases in both experimental and human pathology settings, providing a rationale for new therapeutic interventions based on metabolism-targeted antifibrotic agents.

Role of Fenofibrate Use in Dyslipidemia and Related Comorbidities in the Asian Population: A Narrative Review

Hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) persist despite statin therapy, contributing to residual atherosclerotic cardiovascular disease (ASCVD) risk. Asian subjects are metabolically more susceptible to hypertriglyceridemia than other ethnicities. Fenofibrate regulates hypertriglyceridemia, raises HDL-C levels, and is a recommended treatment for dyslipidemia. However, data on fenofibrate use across different Asian regions are limited. This narrative review summarizes the efficacy and safety data of fenofibrate in Asian subjects with dyslipidemia and related comorbidities (diabetes, metabolic syndrome, diabetic retinopathy, and diabetic nephropathy). Long-term fenofibrate use resulted in fewer cardiovascular (CV) events and reduced the composite of heart failure hospitalizations or CV mortality in type 2 diabetes mellitus. Fenofibrate plays a significant role in improving irisin resistance and microalbuminuria, inhibiting inflammatory responses, and reducing retinopathy incidence. Fenofibrate plus statin combination significantly reduced composite CV events risk in patients with metabolic syndrome and demonstrated decreased triglyceride and increased HDL-C levels with an acceptable safety profile in those with high CV or ASCVD risk. Nevertheless, care is necessary with fenofibrate use due to possible hepatic and renal toxicities in vulnerable individuals. Long-term trials and real-world studies are needed to confirm the clinical benefits of fenofibrate in the heterogeneous Asian population with dyslipidemia.

Associations of omega-3 fatty acids vs. fenofibrate with adverse cardiovascular outcomes in people with metabolic syndrome: propensity matched cohort study

AIMS

Omega-3 fatty acids and fenofibrates have shown some beneficial cardiovascular effects; however, their efficacy has not been compared. This study aimed to compare the effectiveness of currently available omega-3 fatty acids and fenofibrate for reducing major adverse cardiovascular events (MACE).

METHODS AND RESULTS

From a nationwide population-based cohort in South Korea (2008-2019), individuals with metabolic syndrome (≥30 years) who received statin with omega-3 fatty acids and those receiving statin with fenofibrate were matched by propensity score (n = 39 165 in both groups). The primary outcome was MACE, including ischaemic heart disease (IHD), ischaemic stroke (IS), and death from cardiovascular causes. The risk of MACE was lower [hazard ratio (HR), 0.79; 95% confidence interval (CI), 0.74-0.83] in the fenofibrate group than in the omega-3 fatty acid group. Fenofibrate was associated with a lower incidence of IHD (HR, 0.72; 95% CI, 0.67-0.77) and hospitalization for heart failure (HR, 0.90; 95% CI, 0.82-0.97), but not IS (HR, 0.90; 95% CI, 0.81-1.00) nor death from cardiovascular causes (HR, 1.07; 95% CI, 0.97-1.17). The beneficial effect of fenofibrate compared to omega-3 fatty acids was prominent in patients with preexisting atherosclerotic cardiovascular disease and those receiving lower doses of omega-3 fatty acids (≤2 g per day).

CONCLUSION

In a real-world setting, fenofibrate use was associated with a lower risk of MACE compared with low-dose omega-3 fatty acids when added to statins in people with metabolic syndrome.

Myocardial Metabolism in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is increasingly prevalent and now accounts for half of all heart failure cases. This rise is largely attributed to growing rates of obesity, hypertension, and diabetes. Despite its prevalence, the pathophysiological mechanisms of HFpEF are not fully understood. The heart, being the most energy-demanding organ, appears to have a compromised bioenergetic capacity in heart failure, affecting all phenotypes and aetiologies. While metabolic disturbances in heart failure with reduced ejection fraction (HFrEF) have been extensively studied, similar insights into HFpEF are limited. This review collates evidence from both animal and human studies, highlighting metabolic dysregulations associated with HFpEF and its risk factors, such as obesity, hypertension, and diabetes. We discuss how changes in substrate utilisation, oxidative phosphorylation, and energy transport contribute to HFpEF. By delving into these pathological shifts in myocardial energy production, we aim to reveal novel therapeutic opportunities. Potential strategies include modulating energy substrates, improving metabolic efficiency, and enhancing critical metabolic pathways. Understanding these aspects could be key to developing more effective treatments for HFpEF.

Role of fenofibrate in multiple sclerosis

Multiple sclerosis (MS) is the most frequent inflammatory and demyelinating disease of the central nervous system (CNS). The underlying pathophysiology of MS is the destruction of myelin sheath by immune cells. The formation of myelin plaques, inflammation, and injury of neuronal myelin sheath characterizes its neuropathology. MS plaques are multiple focal regions of demyelination disseminated in the brain's white matter, spinal cords, deep grey matter, and cerebral cortex. Fenofibrate is a peroxisome proliferative activated receptor alpha (PPAR-α) that attenuates the inflammatory reactions in MS. Fenofibrate inhibits differentiation of Th17 by inhibiting the expression of pro-inflammatory signaling. According to these findings, this review intended to illuminate the mechanistic immunoinflammatory role of fenofibrate in mitigating MS neuropathology. In conclusion, fenofibrate can attenuate MS neuropathology by modulating different pathways, including oxidative stress, autophagy, mitochondrial dysfunction, inflammatory-signaling pathways, and neuroinflammation.

Mitochondrial complex I inhibition triggers NAD+-independent glucose oxidation via successive NADPH formation, "futile" fatty acid cycling, and FADH2 oxidation

Inhibition of mitochondrial complex I (NADH dehydrogenase) is the primary mechanism of the antidiabetic drug metformin and various unrelated natural toxins. Complex I inhibition can also be induced by antidiabetic PPAR agonists, and it is elicited by methionine restriction, a nutritional intervention causing resistance to diabetes and obesity. Still, a comprehensible explanation to why complex I inhibition exerts antidiabetic properties and engenders metabolic inefficiency is missing. To evaluate this issue, we have systematically reanalyzed published transcriptomic datasets from MPP-treated neurons, metformin-treated hepatocytes, and methionine-restricted rats. We found that pathways leading to NADPH formation were widely induced, together with anabolic fatty acid biosynthesis, the latter appearing highly paradoxical in a state of mitochondrial impairment. However, concomitant induction of catabolic fatty acid oxidation indicated that complex I inhibition created a "futile" cycle of fatty acid synthesis and degradation, which was anatomically distributed between adipose tissue and liver in vivo. Cofactor balance analysis unveiled that such cycling would indeed be energetically futile (-3 ATP per acetyl-CoA), though it would not be redox-futile, as it would convert NADPH into respirable FADH2 without any net production of NADH. We conclude that inhibition of NADH dehydrogenase leads to a metabolic shift from glycolysis and the citric acid cycle (both generating NADH) towards the pentose phosphate pathway, whose product NADPH is translated 1:1 into FADH2 by fatty acid cycling. The diabetes-resistant phenotype following hepatic and intestinal complex I inhibition is attributed to FGF21- and GDF15-dependent fat hunger signaling, which remodels adipose tissue into a glucose-metabolizing organ.

Intensive Glycemic Therapy in Type 2 Diabetes Patients With Cardiac Autonomic Dysfunction: The ACCORD Trial

OBJECTIVE

To assess whether the presence of cardiac autonomic dysfunction denoted by low heart rate variability (HRV) modifies the effect of intensive glycemic therapy on outcomes in patients with type 2 diabetes.

PATIENTS AND METHODS

This study included 7946 participants in the ACCORD (Action to Control Cardiovascular Risk in Diabetes) trial from January 2001 through June 2009. Heart rate variability measures included standard deviation of all normal-to-normal intervals (SDNN) and root mean square of successive differences between normal-to-normal intervals (rMSSD). Abnormal values were defined based on less than the 10th percentile for SDNN and rMSSD.

RESULTS

Compared with standard therapy, intensive therapy was associated with improved primary outcome (composite of cardiovascular events) in the low-HRV group (SDNN: HR, 0.57; 95% CI, 0.39 to 0.84; rMSSD: HR, 0.57; 95% CI, 0.38 to 0.84), but not in the normal-HRV group (SDNN: HR, 0.90; 95% CI, 0.77 to 1.05; rMSSD: HR, 0.90; 95% CI, 0.77 to 1.05). A similar pattern was found for coronary heart disease. Conversely, intensive therapy had a neutral effect on all cause death in the low-HRV group (SDNN: HR, 0.88; 95% CI, 0.54 to 1.41; rMSSD: HR, 0.71; 95% CI, 0.43 to 1.17;), but increase risk of all-cause death in the normal-HRV group (SDNN: HR, 1.21; 95% CI, 1.00 to 1.46; rMSSD: HR, 1.25; 95% CI, 1.03 to 1.51). Intensive therapy induced a greater risk of hypoglycemia in the normal-HRV group than that in the low-HRV group.

CONCLUSION

Cardiac autonomic dysfunction expressed as low HRV identified subpopulations in ACCORD with more benefits and less harms from intensive therapy.

Association of frailty index with congestive heart failure, all-cause and cardiovascular mortality among individuals with type 2 diabetes: a study from National Health and Nutrition Examination Surveys (NHANES), 1999-2018

BACKGROUND

Both type 2 diabetes mellitus (T2DM) and frailty are strongly associated with congestive heart failure (CHF). Individuals with T2DM and CHF have a high frailty burden. The association of frailty with HF, all-cause, and cardiovascular mortality in patients with T2DM has not been thoroughly explored.

METHODS

This study included 2894 adults with T2DM from the National Health and Nutrition Examination Survey (NHANES) database over ten cycles (1999-2018) and followed up for all-cause and cardiovascular mortality through 31 December 2019. The frailty index (FI) was calculated using a 46-item deficit model to assess frailty status. Weighted multivariable logistic regression was performed to explore the relationship between frailty and CHF in patients with T2DM. Weighted restricted cubic splines were used to evaluate the non-linear relationship between FI and outcome. All-cause mortality and cardiovascular mortality association with FI was assessed using the Kaplan-Meier curve and COX proportional hazards regression accounting for sampling weights. Subgroup and sensitivity analyses were performed to evaluate the robustness of the results.

RESULTS

After the adjustment of essential confounders, a higher frailty index in T2DM was associated with increased odds of CHF (odds ratio [OR] for per 1-SD increase, 2.02, 95% confidence interval [CI] 1.67-2.45; P < 0.0001). The presence of frailty T2DM (OR, 3.60; 95% CI 2.34-5.54; P < 0.0001) was associated with a significant increase in the prevalence of CHF compared to non-frailty T2DM in a fully adjusted model. During the median follow-up of 6.75 years, per 1-SD increase in FI was associated with a 41% higher risk of all-cause mortality and a 30% higher risk of cardiovascular mortality after being adjusted for all confounders. Similar results were observed when sensitivity analyses were performed. There was also a non-linear relationship between FI and all-cause mortality. In a weighted multivariate COX proportional model adjusted for full confounders, frailty T2DM increased all-cause (HR, 1.86; 95% CI 1.55-2.24; P < 0.0001) and cardiovascular (HR 1.66; 95% CI 1.18-2.33; P = 0.003) mortality and compared to non-frailty T2DM. The positive association of frailty index and all-cause mortality was only in participants without CHF. The positive association of frailty index and cardiovascular mortality was only in non-anti-diabetic drug users.

CONCLUSIONS

Frailty index in T2DM was positively associated with CHF in linear fashions. The Frailty index was positively correlated with all-cause and cardiovascular death in patients with T2DM. Frailty T2DM was positively associated with CHF, all-cause mortality, and cardiovascular mortality compared to non-frailty T2DM. Promoting frailty measurement and management in T2DM may be beneficial to reduce the burden of CHF and mortality.

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.

Myocardial Metabolism in Heart Failure

PURPOSE OF REVIEW

Myocardial metabolism is intricately linked to cardiac function. Perturbations of cardiac energy metabolism result in an energy-starved heart and the development of contractile dysfunction. In this review, we discuss alterations in myocardial energy supply, transcriptional changes in response to different energy demands, and mitochondrial function in the development of heart failure.

RECENT FINDINGS

Recent studies on substrate modulation through modifying energy substrate supply have shown cardioprotective properties. In addition, large cardiovascular outcome trials of anti-diabetic agents have demonstrated prognostic benefit, suggesting the importance of myocardial metabolism in cardiac function. Understanding molecular and transcriptional controls of cardiac metabolism promises new research avenues for metabolic treatment targets. Future studies assessing the impact of substrate modulation on cardiac energetic status and function will better inform development of metabolic therapies.

Continuation of fibrate therapy in patients with metabolic syndrome and COVID-19: a beneficial regime worth pursuing

Based on separate protective mechanisms related to lipid metabolism, viral cell entry and inflammation, fibrate treatment might be advantageous among patients who have been taking fibrates before SARS-CoV-2 infection and continue taking them during the infection. Based on published data on hospitalized COVID-19 patients, we recommend that the clinicians should ask their patients with metabolic syndrome who are already taking fibrates to continue fibrate treatment during the COVID-19 illness. This recommendation applies to both outpatients and hospitalized patients. However, results from the ongoing randomized controlled trials (RCTs) using fenofibrate treatment for the prevention or treatment of COVID-19 have yet to prove that fenofibrate is clinically significant for this indication.KEY MESSAGESThe role of fibrates as a repurpose to treat SARS-CoV-2 is under investigation in at least three ongoing RCTs.Obesity, diabetes, hypertension and dyslipidaemia, individually or clustered as a discrete phenotype, the metabolic syndrome, typically associate with a more severe course of COVID-19.Fibrate treatment seems to be most advantageous among patients who have been taken fibrates before SARS-CoV-2 infection and are continuing to take them during the infection.We recommend that the clinicians encourage their patients who are already taking fibrate to continue using the drug throughout the COVID-19 illness.