Fish oils--adjuvant therapy in chronic heart failure?

Polymer Conjugation of Docosahexaenoic Acid Potentiates Cardioprotective Therapy in Preclinical Models of Myocardial Ischemia/Reperfusion Injury

While coronary angioplasty represents an effective treatment option following acute myocardial infarction, the reperfusion of the occluded coronary artery can prompt ischemia-reperfusion (I/R) injury that significantly impacts patient outcomes. As ω-3 polyunsaturated fatty acids (PUFAs) have proven, yet limited cardioprotective abilities, an optimized polymer-conjugation approach is reported that improves PUFAs bioavailability to enhance cardioprotection and recovery in animal models of I/R-induced injury. Poly-l-glutamic acid (PGA) conjugation improves the solubility and stability of di-docosahexaenoic acid (diDHA) under physiological conditions and protects rat neonatal ventricular myocytes from I/R injury by reducing apoptosis, attenuating autophagy, inhibiting reactive oxygen species generation, and restoring mitochondrial membrane potential. Enhanced protective abilities are associated with optimized diDHA loading and evidence is provided for the inherent cardioprotective potential of PGA itself. Pretreatment with PGA-diDHA before reperfusion in a small animal I/R model provides for cardioprotection and limits area at risk (AAR). Furthermore, the preliminary findings suggest that PGA-diDHA administration in a swine I/R model may provide cardioprotection, limit edema and decrease AAR. Overall, the evaluation of PGA-diDHA in relevant preclinical models provides evidence for the potential of polymer-conjugated PUFAs in the mitigation of I/R injury associated with coronary angioplasty.

Association between the docosahexaenoic acid to arachidonic acid ratio and acute coronary syndrome: a multicenter observational study

Background

A low eicosapentaenoic acid (EPA) to arachidonic acid (AA) ratio is a known risk for acute coronary syndrome (ACS). However, the association between the docosahexaenoic acid (DHA) to AA ratio and ACS remains unclear. This study aimed to assess the association between the DHA/AA ratio and ACS by patient characteristics.

Methods

We enrolled 1733 patients and evaluated the serum levels of polyunsaturated fatty acids in 5 cardiology departments in a metropolitan area of Japan. We assessed the relationship between the DHA/AA ratio (median cut-off value: 0.903) and ACS according to the following 10 subgroups: sex, age, diabetes mellitus, hypertension, dyslipidemia, smoking history, family history of ischemic heart disease, chronic kidney disease, obesity, and history of coronary revascularization.

Results

Interaction tests in the 10 subgroup analyses revealed a significant difference for adjusted log odds ratios between male and females (p = 0.01), and those with and without hypertension (p = 0.06). Especially in the subgroup based on sex difference, a high DHA/AA ratio was significantly associated with a low risk of ACS among men (adjusted odds ratio = 0.389; 95 % confidence interval: 0.211–0.716). In contrast, a reverse association was found among women, although this was not statistically significant (adjusted odds ratio = 3.820; 95 % confidence interval: 0.718–20.325).

Conclusions

The association between the DHA/AA ratio and ACS differed by clinical characteristic. Notably, patients with a low DHA/AA ratio had a higher risk of ACS than those with a high DHA/AA ratio, and this was significant for men in particular.

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).

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.

Effects of fish oil supplementation on inflammatory markers in chronic heart failure: a meta-analysis of randomized controlled trials

Background

Effects of fish oil on systematic inflammation in chronic heart failure remain unclear. In this meta-analysis, we aimed to evaluate the influence of fish oil supplementation on circulating levels of inflammatory markers in patients with chronic heart failure.

Methods

Human randomized controlled trials, which compared the effects of fish oil supplementation with placebo in patients with chronic heart failure, were identified by systematic search of Medline, Embase, Cochrane’s library and references cited in related reviews and studies up to November 2011. Outcome measures comprised the changes of circulating inflammatory markers. Meta-analysis was performed with the fixed-effect model or random-effect model according to the heterogeneity.

Results

A total of seven trials with eight study arms were included. The pooled results indicated circulating levels of tumor necrosis factor α (SMD = -0.62, 95% CI -1.08 to -0.16, p = 0.009), interleukin 1 (SMD = -1.24, 95% CI -1.56 to -0.91, p < 0.001) and interleukin 6 (SMD = -0.81, 95% CI -1.48 to -0.14, p = 0.02) were significantly decreased after fish oil supplementation; however, high sensitivity C reactive protein, soluble intracellular adhesion molecular 1 and vascular cell adhesion molecular 1 were not significantly affected. Meta-regression and subgroup analysis results suggested the difference in dose of fish oil and follow-up duration might influence the effects of fish oil on tumor necrosis factor α and interleukin 6. Greater reduction of these two markers might be achieved in patients taking fish oil of a higher dose (over 1000 mg/day) or for a longer duration (over 4 months).

Conclusions

Limited evidence suggests anti-inflammation may be a potential mechanism underlying the beneficial effects of fish oil for chronic heart failure. Further large-scale and adequately powered clinical trials are needed to confirm these effects.

Nutritional and anti-inflammatory interventions in chronic heart failure

Currently, there are 5 million individuals with chronic heart failure (CHF) in the United States who have poor clinical outcomes, including high death rates. Observational studies have indicated a reverse epidemiology of traditional cardiovascular risk factors in CHF; in contrast to trends seen in the general population, obesity and hypercholesterolemia are associated with improved survival. The temporal discordance between the overnutrition (long-term killer) and undernutrition (short-term killer) not only can explain some of the observed paradoxes but also may indicate that malnutrition, inflammation, and oxidative stress may play a role that results in protein-energy wasting contributing to poor survival in CHF. Diminished appetite or anorexia and nutritional deficiencies may be both a cause and a consequence of this so-called malnutrition-inflammation-cachexia (MIC) or wasting syndrome in CHF. Neurohumoral activation, insulin resistance, cytokine activation, and survival selection-resultant genetic polymorphisms also may contribute to the prominent inflammatory and oxidative characteristics of this population. In patients with CHF and wasting, nutritional strategies including amino acid supplementation may represent a promising therapeutic approach, especially if the provision of additional amino acids, protein, and energy includes nutrients with anti-inflammatory and antioxidant properties. Regardless of the etiology of anorexia, appetite-stimulating agents, especially those with anti-inflammatory properties such as megesterol acetate or pentoxyphylline, may be appropriate adjuncts to dietary supplementation. Understanding the factors that modulate MIC and body wasting and their associations with clinical outcomes in CHF may lead to the development of nutritional strategies that alter the pathophysiology of CHF and improve outcomes.

Pericardial delivery of omega-3 fatty acid: a novel approach to reducing myocardial infarct sizes and arrhythmias

Basic and clinical evidence suggests that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) decrease fatal arrhythmias and infarct sizes. This study investigated if pericardial delivery of n-3 PUFAs would protect the myocardium from ischemic damages and arrhythmias. Acute myocardial infarctions were induced in 23 pigs with either 45 min balloon inflations or clamp occlusions of the left anterior descending coronary arteries and 180 min reperfusion. Docosahexaenoic acid (C22:6n-3, DHA, 45 mg), one of the main n-3 PUFAs in fish oil, was infused within the pericardial space only during the 40-min stabilizing phase, 45 min ischemia and initial 5 min reperfusion. Hemodynamics and cardiac functions were very similar between the DHA-treated and control groups. However, DHA therapy significantly reduced infarct sizes from 56.8 ± 4.9% for controls ( n = 12) to 28.8 ± 7.9% ( P < 0.01) for DHA-treated animals ( n = 11). Compared with controls, DHA-treated animals significantly decreased heart rates and reduced ventricular arrhythmia scores during ischemia. Furthermore, three (25%) control animals experienced eight episodes of ventricular fibrillation (VF), and two died subsequent to unsuccessful defibrillation. In contrast, only 1 (9%) of 11 DHA-treated pigs elicited one episode of VF that was successfully converted via defibrillation to normal rhythm; thus, mortality was reduced from 17% in the controls to 0% in the DHA-treated animals. These data demonstrate that pericardial infusion of n-3 PUFA DHA can significantly reduce both malignant arrhythmias and infarct sizes in a porcine infarct model. Pericardial administration of n-3 PUFAs could represent a novel approach to treating or preventing myocardial infarctions.

Increased shear stress with upregulation of VEGF-A and its receptors and MMP-2, MMP-9, and TIMP-1 in venous stenosis of hemodialysis grafts

Venous injury and subsequent venous stenosis formation are responsible for hemodialysis graft failure. Our hypothesis is that these pathological changes are in part related to changes in wall shear stress (WSS) that results in the activation of matrix regulatory proteins causing subsequent venous stenosis formation. In the present study, we examined the serial changes in WSS, blood flow, and luminal vessel area that occur subsequent to the placement of a hemodialysis graft in a porcine model of chronic renal insufficiency. We then determined the corresponding histological, morphometric, and kinetic changes of several matrix regulatory proteins including VEGF-A, its receptors, matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1, and TIMP-2. WSS was estimated by obtaining blood flow and luminal vessel area by performing phase-contrast MRI with magnetic resonance angiography in 21 animals at 1 day after graft placement and prior to death on day 3 (n = 7), day 7 (n = 7), and day 14 (n = 7). At all time points, the mean WSS at the vein-to-graft anastomosis was significantly higher than that at the control vein (P < 0.05). WSS had a bimodal distribution with peaks on days 1 and 7 followed by a significant reduction in WSS by day 14 (P < 0.05 compared with day 7) and a decrease in luminal vessel area compared with control vessels. By day 3, there was a significant increase in VEGF-A and pro-MMP-9 followed by, on day 7, increased pro-MMP-2, active MMP-2, and VEGF receptor (VEGFR)-2 (P < 0.05) and, by day 14, increased VEGFR-1 and TIMP-1 (P < 0.05) at the vein-to-graft anastomosis compared with control vessels. Over time, the neointima thickened and was composed primarily of alpha-smooth muscle actin-positive cells with increased cellular proliferation. Our data suggest that hemodialysis graft placement leads to early increases in WSS, VEGF-A, and pro-MMP-9 followed by subsequent increases in pro-MMP-2, active MMP-2, VEGFR-1, VEGFR-2, and TIMP-1, which may contribute to the development of venous stenosis.