Omega-3 fatty acids and heart failure

Therapeutic potential of omega-3 fatty acid-derived epoxyeicosanoids in cardiovascular and inflammatory diseases

Numerous benefits have been attributed to dietary long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs), including protection against cardiac arrhythmia, triglyceride-lowering, amelioration of inflammatory, and neurodegenerative disorders. This review covers recent findings indicating that a variety of these beneficial effects are mediated by "omega-3 epoxyeicosanoids", a class of novel n-3 LC-PUFA-derived lipid mediators, which are generated via the cytochrome P450 (CYP) epoxygenase pathway. CYP enzymes, previously identified as arachidonic acid (20:4n-6; AA) epoxygenases, accept eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), the major fish oil n-3 LC-PUFAs, as efficient alternative substrates. In humans and rodents, dietary EPA/DHA supplementation causes a profound shift of the endogenous CYP-eicosanoid profile from AA- to EPA- and DHA-derived metabolites, increasing, in particular, the plasma and tissue levels of 17,18-epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP). Based on preclinical studies, these omega-3 epoxyeicosanoids display cardioprotective, vasodilatory, anti-inflammatory, and anti-allergic properties that contribute to the beneficial effects of n-3 LC-PUFAs in diverse disease conditions ranging from cardiac disease, bronchial disorders, and intraocular neovascularization, to allergic intestinal inflammation and inflammatory pain. Increasing evidence also suggests that background nutrition as well as genetic and disease state-related factors could limit the response to EPA/DHA-supplementation by reducing the formation and/or enhancing the degradation of omega-3 epoxyeicosanoids. Recently, metabolically robust synthetic analogs mimicking the biological activities of 17,18-EEQ have been developed. These drug candidates may overcome limitations of dietary EPA/DHA supplementation and provide novel options for the treatment of cardiovascular and inflammatory diseases.

Association between omega-3 fatty acids consumption and the risk of type 2 diabetes: A meta-analysis of cohort studies

Aims/Introduction

Epidemiological evidence for the effect of omega‐3 fatty acids on the risk of type 2 diabetes is controversial. A meta‐analysis based on prospective cohorts was carried out to evaluate this issue.

Materials and Methods

Pooled diabetic risk was calculated using a fixed or random effects model. The dose–response relationship was assessed by meta‐regression analysis.

Results

The study showed that consumption of single omega‐3 was associated with an increased risk of type 2 diabetes (relative risk [RR] = 1.45, P < 0.001); whereas the RR for mixed omega‐3 was statistically insignificant. The dose–response curve presented an inverted U‐shape of diabetes risk corresponding to the dose of omega‐3 consumption. Subanalysis showed that omega‐3 was inversely associated with type 2 diabetes risk in Asians (RR = 0.82, P < 0.001); whereas the risk was increased in Westerners (RR = 1.30, P < 0.001). Studies with follow‐up duration ≥16 years and baseline age ≥54 years showed a positive association between type 2 diabetes risk and omega‐3 intake.

Conclusions

The present findings suggest that dosage and composition of omega‐3, ethnicity, trial duration, and age could influence the effect of omega‐3 on type 2 diabetes progression.

Omacor and omega-3 fatty acids for treatment of coronary artery disease and the pleiotropic effects

Omega-3 polyunsaturated fatty acids are found in fish oil and they have been shown to mitigate the risk of cardiovascular disease. Omega-3 fatty acids are essential fatty acids because they cannot be synthesized de novo and must be consumed from dietary sources such as marine fish. It reduces fatal and nonfatal myocardial infarction, stroke, coronary artery disease, sudden cardiac death, and all-cause mortality. It also has beneficial effects in mortality reduction after a myocardial infarction. Omacor is a highly potent form of Omega-3 fatty acids that lowers plasma triglycerides. In patients with severe hypertriglyceridemia who are refractory to statins, it helps augment triglyceride reduction. Omacor also increases high-density lipoprotein and decreases low-density lipoprotein levels. It is well tolerated with minimal adverse effects and no known interactions causing rhabdomyolysis. In high doses, Omacor has pronounced cardiovascular benefits with improvement of triglycerides and various lipid parameters. Omega-3 fatty acids have also been shown to have beneficial effects on arrhythmias, inflammation, and heart failure. It may also decrease platelet aggregation and induce vasodilation. Omega-3 fatty acids also reduce atherosclerotic plaque formation and stabilize plaques preventing plaque rupture leading to acute coronary syndrome. Moreover, omega-3 fatty acids may have antioxidant properties that improve endothelial function and may contribute to its antiatherosclerotic benefits. In this review, we sought to provide the current literature on the use of omega-3 fatty acids and the potent formulation Omacor in the treatment of coronary artery disease.

Novel regulatory roles of omega-3 fatty acids in metabolic pathways: a proteomics approach

Background

Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been shown to alleviate the symptoms of metabolic disorders, such as heart disease, diabetes, obesity and insulin resistance. Several putative mechanisms by which n-3 PUFA elicit beneficial health effects have been proposed; however, there is still a shortage of knowledge on the proteins and pathways that are regulated by n-3 PUFA.

Methods

Using two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, we investigated the effects of diets high or low in n-3 PUFA on hepatic proteomic profile of C57BL/6 mice.

Results

The findings show for the first time that high dietary n-3 PUFA reduced the expression of regucalcin, adenosine kinase and aldehyde dehydrogenase. On the other hand, diets high in n-3 PUFA increased the expression of apolipoprotein A-I, S-adenosylmethionine synthase, fructose-1, 6-bisphosphatase, ketohexokinase, malate dehydrogenase, GTP-specific succinyl CoA synthase, ornithine aminotransferase and protein disulfide isomerase-A3.

Conclusions

Our findings revealed for the first time that n-3 PUFA causes alterations in several novel functional proteins involved in regulating lipid, carbohydrate, one-carbon, citric acid cycle and protein metabolism, suggesting integrated regulation of metabolic pathways. These novel proteins are potential targets to develop therapeutic strategies against metabolic disorders.

ELOVL2 gene polymorphisms are associated with increases in plasma eicosapentaenoic and docosahexaenoic acid proportions after fish oil supplement

Fish oil supplementation provides an inconsistent degree of protection from cardiovascular disease (CVD), which may be attributed to genetic variation. Single nucleotide polymorphisms (SNPs) in the elongation-of-very-long-chain-fatty-acids-2 (ELOVL2) gene have been strongly associated with plasma proportions of n-3 long-chain polyunsaturated fatty acids (LC-PUFA). We investigated the effect of genotype interaction with fish oil dosage on plasma n-3 LC-PUFA proportions in a parallel double-blind controlled trial, involving 367 subjects randomised to treatment with 0.45, 0.9 and 1.8 g/day eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (1.51:1) or olive oil placebo for 6 months. We genotyped 310 subjects for ELOVL2 gene SNPs rs3734398, rs2236212 and rs953413. At baseline, carriers of all minor alleles had lower proportions of plasma DHA than non-carriers (P = 0.021-0.030). Interaction between genotype and treatment was a significant determinant of plasma EPA (P < 0.0001) and DHA (P = 0.004-0.032). After the 1.8 g/day dose, carriers of ELOVL2 SNP minor alleles had approximately 30 % higher proportions of EPA (P = 0.002-0.004) and 9 % higher DHA (P = 0.013-0.017) than non-carriers. Minor allele carriers could therefore particularly benefit from a high intake of EPA and DHA in maintaining high levels of plasma n-3 PUFA conducive to protection from CVD.

Effect of omega-3 on brain natriuretic peptide and echocardiographic findings in heart failure: Double-blind placebo-controlled randomized trial

BACKGROUND

Possible beneficial effects of dietary omega-3 supplementation on patients with congestive heart failure (CHF) were investigated.

METHODS AND RESULTS

100 patients with CHF who had a tri-chamber pacemaker and automated defibrillator were initially recruited, and 70 agreed to participate.38 patients received 2 g/day of omega-3 and 32 received placebo capsules. BNP level, 6-min walk test and echocardiographic parameters were recorded at baseline and after 6 months of treatment. BNP levels decreased significantly after 6 months in the omega-3 group, from 1766.2 ± 1978.1 pg/mL to 1159.4 ± 1430.9 pg/dL (P < 0.005). Tei index and late diastolic velocity index were significantly improved in treated group. Mortality and hospitalization rates did not differ.

CONCLUSION

The beneficial effects of omega-3 supplementation in patients with CHF were not as clear as hypothesized; however, omega-3 fatty acids can result in small changes in plasma BNP levels and modest improvements in echocardiographically assessed diastolic function (Clinical trial.gov registration: NCT01227837).

The use of ω-3 poly-unsaturated fatty acids in heart failure: a preferential role in patients with diabetes

PURPOSE

To review the evidence for a beneficial effect of ω-3 PUFAs in heart failure (HF) and its co-morbidities, their possible preferential effect in diabetes and the potential mechanism for their benefit.

METHODS

We summarize the clinical studies which investigated the use of ω-3 PUFAs in patients with HF with an emphasis on diabetes. We briefly summarize the evidence for an effect of ω-3 PUFAs in patients with coronary artery disease (CAD), atrial fibrillation (AF) and ventricular arrhythmias. We also discuss the proposed mechanisms of ω-3 PUFA action in cardiovascular diseases.

RESULTS

While there is emerging evidence for a beneficial effect of ω-3 PUFA supplementation in patients with HF, the evidence for other indications have been variable and conflicting. In HF patients with diabetes, ω-3 PUFAs may have a preferential therapeutic benefit. Randomized controlled trials did not show considerable beneficial effects of ω-3 PUFAs in other conditions such as CAD and AF. In a diabetic and insulin-resistant state, ω-3 PUFAs bind to the G-protein coupled receptor, GPR120, resulting in reduced cytokine production from inflammatory macrophages and improved signaling in adipocytes, leading to a reduction in insulin resistance.

CONCLUSIONS

There is promising evidence showing that use of ω-3 PUFA supplementation improves clinical outcomes of HF patients with diabetes. Further clinical trials are needed in this regard.

Tetradecylthioacetic acid increases fat metabolism and improves cardiac function in experimental heart failure

Changes in myocardial metabolism, including a shift from fatty acid to glucose utilization and changes in fatty acid availability and composition are characteristics of heart failure development. Tetradecylthioacetic acid (TTA) is a fatty acid analogue lacking the ability to undergo mitochondrial β-oxidation. TTA promotes hepatic proliferation of mitochondria and peroxisomes and also decreases serum triglycerides and cholesterol in animals. We investigated the effect of TTA, in combination with a high-fat or regular diet, in a rat model of post-myocardial infarction heart failure. TTA had a beneficial effect on cardiac function in post-myocardial infarction heart failure without affecting myocardial remodeling. These effects of TTA on myocardial function were accompanied by decreased free fatty acids in plasma, increased myocardial proportion of n-3 polyunsaturated fatty acids (PUFA) and a decreased proportion of n-6 PUFA. Myocardial enzyme gene expression during TTA treatment suggested that the increase in n-3 PUFA could reflect increased n-3 PUFA synthesis and inadequately increased n-3 PUFA β-oxidation. Based on our data, it is unlikely that the changes are secondary to alterations in other tissues as plasma and liver showed an opposite pattern with decreased n-3 PUFA during TTA treatment. The present study suggests that TTA may improve myocardial function in heart failure, potentially involving its ability to decrease the availability of FFA and increase the myocardial proportion of n-3 PUFA.

Why Do We Still Need Large Scale Clinical Trial: The Case of n-3 PUFA

After the first reports about a protective effect on coronary heart disease (CHD) published more than 40 years ago, wide interest in the therapeutic use of n-3 polyunsaturated fatty acids (n-3 PUFA) aroused. Since then, many studies and meta-analyses have reported a significantly reduced risk of CHD and CV death due to fish and n-3 PUFA intake. Some of the overviews reported a significant reduction of risk of sudden cardiac death, all-cause death, and nonfatal CV events. On the other side, recent clinical trials had mixed findings, raising concern about the consistency of the evidence on n-3 PUFA. We critically reviewed recent large clinical trials reporting data on the antiarrhythmic effects of n-3 PUFA in different clinical settings, i.e., patients with CHD, heart failure, with implantable cardioverter defibrillator, and at risk of atrial fibrillation, in order to summarize the results which are available up to date and possibly give "substantiated" fuel to the debate on the conflicting results of n-3 PUFA.

Medical therapy for chronic heart failure

Understanding of contemporary pharmacological therapy for chronic heart failure continues to evolve. In this Review, we discuss how findings from clinical trials have caused the roles of old therapies to be expanded and past treatment algorithms to be challenged. Several trials investigating preserved ejection fraction as a measure of heart failure had disappointing results, although important studies are in progress. Many novel therapeutic approaches for heart failure have emerged and are discussed in this review. The pharmacological treatments for heart failure continue to change, with many exciting possibilities for the future.