Fish consumption, n-3 fatty acids in cell membranes, and heart rate variability in survivors of myocardial infarction with left ventricular dysfunction

Babassu (Attalea glassmanii Zona) Nut Oil Is More Effective than Olive Oil for Treating Ischemia-Reperfusion Injury

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in Western civilizations. The type of fatty acid which makes up the diet is related to the cardiovascular morbimortality and the formation of atheromas. Populations with high consumption of oils and fats have a higher number of deaths from CVD.

PURPOSE

In the present study, the objective was to comparatively analyze the microcirculatory effects of unrefined babassu oil with olive oil in microcirculation and liver of male hamsters of the species Mesocricetus auratus, checking the permeability to macromolecules after ischemia-reperfusion (I/R) without and with topical application of histamine 5 × 10-6 M. This is an experimental study, using as model the hamster's cheek pouch, which was prepared for intravital microscopy. The hamsters were divided into seven groups and orally treated for 14 days, twice a day (at 8 AM and 4 PM), orally received treatments in the following doses: unrefined babassu oil (BO) 0.02 mL/dose (group BO-2), 0.06 mL/dose (group BO-6), and 0.18 mL/dose (BO-18 group); extra virgin olive oil (OI) 0.02 mL/dose (group OI-2), 0.06 mL/dose (group OI-6), and 0.18 mL/dose (OI-18 group); and mineral oil (MO) 0.18 mL/dose (MO-18 group). The observations were made on the 15th day on the hamsters' cheek pouch; the increase of vascular permeability induced by I/R with and without histamine application was evaluated, and in the liver the biological material was collected aseptically then fixed in 10% buffered formalin.

RESULTS

Microcirculatory analyses showed a significant reduction in the number of leaks after I/R with and without the topical use of histamine in animals treated with unrefined BO 0.06 mL/dose (BO-6) and 0.18 mL/dose (BO-18) compared to animals treated with OI. The BO group (p < 0.001) presented a dose-response relationship for decreasing leaks after I/R with and without topical use of histamine. Histological liver analyses showed no fat deposition changes in any of the treatment groups. Phytochemical analyses evidenced a chemical compound (C31H60NO8) in unrefined BO but not in OI.

CONCLUSIONS

This experiment demonstrates the protective effect of unrefined BO on the microcirculatory system and its greater dose effect than that of OI. Finding a chemical compound (C31H60NO8) that is present in BO but not in OI opens the possibility of investigating whether this chemical compound was responsible for the protective effect on membrane permeability.

Anti-arrhythmic properties of non-antiarrhythmic medications

Traditional anti-arrhythmic drugs are classified by the Vaughan-Williams classification scheme based on their mechanisms of action, which includes effects on receptors and/or ion channels. Some known anti-arrhythmic drugs do not perfectly fit into this classification scheme. Other medications/molecules with established non-anti-arrhythmic indications have shown anti-arrhythmic properties worth exploring. In this narrative review, we discuss the molecular mechanisms and evidence base for the anti-arrhythmic properties of traditional non-antiarrhythmic drugs such as inhibitors of the renin angiotensin system (RAS), statins and polyunsaturated fatty acids (PUFAs). In summary, RAS antagonists, statins and PUFAs are 'upstream target modulators' that appear to have anti-arrhythmic roles. RAS blockers prevent the downstream arrhythmogenic effects of angiotensin II - the main effector peptide of RAS - and the angiotensin type 1 receptor. Statins have pleiotropic effects including anti-inflammatory, immunomodulatory, modulation of autonomic nervous system, anti-proliferative and anti-oxidant actions which appear to underlie their anti-arrhythmic properties. PUFAs have the ability to alter ion channel function and prevent excessive accumulation of calcium ions in cardiac myocytes, which might explain their benefits in certain arrhythmic conditions. Clearly, whilst a number of anti-arrhythmic drugs exist, there is still a need for randomised trials to establish whether additional agents, including those already in clinical use, have significant anti-arrhythmic effects.

Effect of the double bond conjugation on the vascular physiology and nitric oxide production of isomers of eicosapentaenoic and docosahexaenoic acids prepared from shark oil

A collection of evidence suggests that conjugation of double bonds of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, omega-3 polyunsaturated fatty acids (n-3 PUFAs), increases their anticarcinogenic activity; however, the effect of such conjugation on vascular tone activity remains unknown. We propose that the mixture of conjugated PUFAs exerts higher vasorelaxation activity than the corresponding mixture of nonconjugated PUFAs. The vascular response to different concentrations of conjugated and nonconjugated isomers of EPA and DHA, among other fatty acids (FAs) naturally present in shark oil, and the role of nitric oxide (NO) as a vasorelaxant agent were investigated. Both conjugated EPA (CEPA) and conjugated DHA (CDHA) were prepared by alkaline isomerization of all PUFAs contained in shark oil. Different concentrations of conjugated and nonconjugated PUFAs were placed in contact with precontracted aortic rings of Wistar rats to assess their effect on vascular tone. All tested samples exerted a vasorelaxant effect. Compared to nonconjugated PUFAs, conjugated isomers exhibited an increase in the dilatation of the aortic rings (P<0.001) in a dose-dependent manner (P<0.001). In addition, nonconjugated PUFAs produced nitric oxide (NO) in a dose-dependent manner, while conjugated PUFAs did not, suggesting that their dilatation mechanism is not totally dependent on NO.

Fatty Acid Profiles of Triacylglycerols and Phospholipids of Sea-Cage Cultured Trachinotus blochii: A Comparative Study of Head, Viscera, Skin, Bone, and Muscle

Trachinotus blochii (golden pompano) is an economically important cultured marine fish that is rich in polyunsaturated fat. The fatty acid profiles of triacylglycerols and phospholipids of T. blochii tissues were analyzed. Lipid contents in tissues followed the order of viscera (28.27%) > skin (17.25%) ≈ bone (16.18%) ≈ head (15.12%) > muscle (7.38%). In triacylglycerols (TAG), saturated fatty acids (palmitic acid predominated) were preferentially esterified in the sn-2 position, and monounsaturated fatty acids (oleic acid predominated) were mainly distributed in the sn-1, 3 positions. The numbers of n-3 polyunsaturated fatty acids (PUFA) in the sn-2 position were significantly greater than those in positions 1 and 3, while the n-6 PUFA were mainly found in the sn-1, 3 positions. Muscle TAG had a higher content of EPA+DHA (3.90%) than did the other tissues. In phosphatidylethanolamines, EPA+DHA in muscle (6.76%) predominated over that in other tissues. In phosphatidylcholines, EPA+DHA in bone (6.50%) predominated. This study is a guide for the biochemical and nutritional values of the T. blochii species and can be useful for further investigation of industrial applications. PRACTICAL APPLICATION: The high proportion of sn-2-palmitic acid (greater than 50%) is close to that of breast milk and the n-3 PUFA, especially EPA and DHA have the preferential distribution in the sn-2 position of triacylglycerol. Hence, golden pompano is an excellent dietary component for human nutrition and health.

Omega-3 Polyunsaturated Fatty Acids: Benefits and Endpoints in Sport

The influence of nutrition has the potential to substantially affect physical function and body metabolism. Particular attention has been focused on omega-3 polyunsaturated fatty acids (n-3 PUFAs), which can be found both in terrestrial features and in the marine world. They are responsible for numerous cellular functions, such as signaling, cell membrane fluidity, and structural maintenance. They also regulate the nervous system, blood pressure, hematic clotting, glucose tolerance, and inflammatory processes, which may be useful in all inflammatory conditions. Animal models and cell-based models show that n-3 PUFAs can influence skeletal muscle metabolism. Furthermore, recent human studies demonstrate that they can influence not only the exercise and the metabolic response of skeletal muscle, but also the functional response for a period of exercise training. In addition, their potential anti-inflammatory and antioxidant activity may provide health benefits and performance improvement especially in those who practice physical activity, due to their increased reactive oxygen production. This review highlights the importance of n-3 PUFAs in our diet, which focuses on their potential healthy effects in sport.

Mercury, omega-3 fatty acids, and seafood intake are not associated with heart rate variability or QT interval

Mercury (Hg), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) concentrations differ across seafood types. Our aim was to investigate the association of Hg, EPA, and DHA, as well as avid consumption of diverse seafood types, with cardiovascular variables heart rate variability (HRV) and QT interval duration (QTc) in a contemporary population. We measured HRV and QTc by Holter monitor, EPA and DHA in plasma, total Hg in whole blood, and possible confounders in 94 avid seafood consumers from Long Island, NY. Participants had mean Hg of 8.4 mcg/L, mean EPA of 1.2%, and mean DHA of 3.7% of total fatty acids. Adjusted for possible confounders, EPA+DHA, Hg, and total seafood consumption were not associated with HRV or QTc. Associations with consumption of specific seafood types were suggested (eg, tuna steak with QTc and anchovies with HRV) but require verification.

Maternal n-6 and n-3 fatty acid status during pregnancy is related to infant heart rate and heart rate variability: An exploratory study

Early life heart rate (HR) and heart rate variability (HRV) reflect autonomic system maturation. Intervention with n-3 long chain polyunsaturated fatty acids (LCPUFAs) during pregnancy favorably affects fetal HR and HRV, complementing previous observations for n-3 LCPUFA intervention during infancy. The relationship between maternal fatty acid status during pregnancy and infant HR/HRV has not previously been assessed. The aim of this study was to explore associations between maternal n-6 and n-3 fatty acid status during pregnancy and infant HR and HRV at 2 weeks, 4 months, and 6 months of age using linear regression models. Maternal n-3 fatty acids were inversely related to infant HR and positively related to HRV. Conversely, maternal n-6 fatty acids were positively related to infant HR and inversely related to HRV. These data build on existing literature evidencing a role for n-3 fatty acids in accelerating autonomic development and link n-6 fatty acids to HR/HRV.

Modulation of heart rate and heart rate variability by n-3 long chain polyunsaturated fatty acids: Speculation on mechanism(s)

Heart rate (HR) and heart rate variability (HRV) are valuable markers of health. Although the underlying mechanism(s) are controversial, it is well documented that n-3 long chain polyunsaturated fatty acid (LCPUFA) intake improves HR and HRV in various populations. Autonomic modulation and/or alterations in cardiac electrophysiology are commonly cited as potential mechanisms responsible for these effects. This article reviews existing evidence for each and explores a separate mechanism which has not received much attention but has scientific merit. Based on presented evidence, it is proposed that n-3 LCPUFAs affect HR and HRV directly by autonomic modulation and indirectly by altering circulating factors, both dependently and independently of the autonomic nervous system. The evidence for changes in cardiac electrophysiology as the mechanism by which n-3 LCPUFAs affect HR and HRV needs strengthening.

The future for long chain n-3 PUFA in the prevention of coronary heart disease: do we need to target non-fish-eaters?

Dietary guidelines in many countries include a recommendation to consume oily fish, mainly on the basis of evidence from prospective cohort studies that fish consumption is cardioprotective. However, average intakes are very low in a large proportion of the UK population. Some groups, such as vegans and vegetarians, purposely omit fish (along with meat) from their diet resulting in zero or trace intakes of long chain (LC) n-3 PUFA. Although the efficacy of dietary fish oil supplementation in the prevention of CVD has been questioned in recent years, the balance of evidence indicates that LC n-3 PUFA exert systemic pleiotropic effects through their influence on gene expression, cell signalling, membrane fluidity and by conversion to specialised proresolving mediators; autacoid lipid mediators that resolve inflammatory events. The long-term impact of reduced tissue LC n-3 PUFA content on cardiovascular health is surprisingly poorly understood, particularly with regard to how low proportions of LC n-3 PUFA in cell membranes may affect cardiac electrophysiology and chronic inflammation. Randomised controlled trials investigating effects of supplementation on prevention of CHD in populations with low basal LC n-3 PUFA tissue status are lacking, and so the clinical benefits of supplementing non-fish-eating groups with vegetarian sources of LC n-3 PUFA remain to be determined. Refocusing dietary LC n-3 PUFA intervention studies towards those individuals with a low LC n-3 PUFA tissue status may go some way towards reconciling results from randomised controlled trials with the epidemiological evidence.

Marine omega-3 highly unsaturated fatty acids: From mechanisms to clinical implications in heart failure and arrhythmias

Therapeutic implications of marine omega-3 highly unsaturated fatty acids (HUFA) in cardiovascular disease are still discussed controversially. Several clinical trials report divergent findings and thus leave ambiguity on the meaning of oral omega-3 therapy. Potential prognostic indications of HUFA treatment have been predominantly studied in coronary artery disease, sudden cardiac death, ventricular arrhythmias, atrial fibrillation and heart failure of various origin. It is suspected that increased ventricular wall stress is crucially involved in the prognosis of heart failure. Increased wall stress and an unfavorable myocardial remodeling is associated with an increased risk of arrhythmias by stretch-activated membrane ion channels. Integration of HUFA into the microenvironment of cardiomyocyte ion channels lead to allosteric changes and increase the electrical stability. Increased ventricular wall stress appears to be involved in the local myocardial as well as in the hepatic fatty acid metabolism, i.e. a cardio-hepatic syndrome. Influences of an altered endogenous HUFA metabolism and an inverse shift of the fatty acid profile was underrated in the past. A better understanding of these interacting endogenous mechanisms appears to be required for interpreting the findings of recent experimental and clinical studies. The present article critically reviews major studies on basic pathophysiological mechanisms and treatment effects in clinical trials.

The autonomic nervous system and cardiovascular disease: role of n-3 PUFAs

In the last decades, a large body of experimental and clinical evidence has been accumulated showing that cardiovascular diseases are often accompanied by an imbalance in the sympathetic-vagal outflow to the heart, resulting in a chronic adrenergic activation. The arterial baroreceptor system is a key component of mechanisms contributing to the neural regulation of the cardiovascular system. Several methods have been proposed to assess autonomic activity by analyzing heart rate and blood pressure changes either spontaneously occurring or following provocations. The autonomic nervous system has been regarded as one of the putative mechanisms involved into the beneficial effects of exposure to n-3 fatty acids observed in epidemiological studies. The aim of the present review is to provide an update on the clinical evidence proposed so far linking exposure to n-3 fatty acids to autonomic nervous system modulation.

Intrinsic heart rate recovery after dynamic exercise is improved with an increased omega-3 index in healthy males

Dietary fish consumption contributes to a reduced risk of cardiac mortality. In the present study, the effect of low-dose fish oil (FO) supplementation on heart rate (HR) response to intense exercise and recovery was investigated in physically fit males. The subjects (n 26) were supplemented (double-blind, parallel design) with (2 × 1 g/d) soya bean oil (control) or tuna FO providing the long-chain n-3 PUFA DHA (560 mg) and EPA (140 mg). Erythrocyte omega-3 index (%EPA+DHA), HR, HR variability and HR recovery were analysed during rest, intense exercise and recovery at baseline and after 8 weeks of supplementation. The mean erythrocyte omega-3 index, which did not differ between the groups at baseline (control 4·2 (sem 0·2), n 13; FO 4·7 (sem 0·2), n 13), remained unchanged in the control group (3·9 (sem 0·2)), but increased in the FO group (6·3 (sem 0·3); P< 0·01). The mean HR during supine resting conditions (control 56 (sem 10); FO 59 (sem 9)) was not affected by FO supplementation. Poincaré analysis of HR variability at rest exhibited a decreasing trend in parasympathetic activity in the FO group (SD1 (standard deviation of points perpendicular to the axis of line of identity)/SD2 (standard deviation of points along the axis of line of identity): control 0·02 (sem 0·01); FO − 0·05 (sem 0·02); P= 0·18). Peak HR was not affected by supplementation. However, during submaximal exercise over 5 min, fewer total heart beats were recorded in the FO group ( − 22 (sem 6) ( = − 4·5 beats/min)), but not in the control group (+1 (sem 4)) (P< 0·05). Supine HR recovery (half-time) after cycling was significantly faster after FO supplementation (control − 0·4 (sem 1·2) s; FO − 8·0 (sem 1·7) s; P< 0·05). A low intake of FO increased the omega-3 index and reduced the mean exercise HR and improved HR recovery without compromising the peak HR. A direct influence of DHA via reductions in the cardiac intrinsic beat rate was balanced by a reciprocal decrease in vagal tone.

Dietary manipulation of platelet function

Activated platelets contribute to plaque formation within blood vessels in the early and late stages of atherogenesis, and therefore they have been proposed as risk factor for cardiovascular disease. Anti-platelet drugs, such as aspirin, are now the most prescribed pharmacological treatment in Europe. Certain dietary bioactives also beneficially affect platelet function, and with less side effects, albeit that effects are generally more subtle. Therefore, consumption of dietary bioactives could play a role in the prevention of atherothrombotic vascular disease. Here we review the efficacy of dietary treatment strategies, especially those involving certain dietary fatty acids and polyphenols, to modulate platelet function in healthy subjects or in patients with cardiovascular disease. Variation in study populations, small study sizes and lack of comparability between methods to assess platelet function currently limit robust evidence on the efficacy of dietary bioactives in healthy subjects or specific patient groups. Also, limited knowledge of the metabolism of dietary bioactives, and therefore of the bioavailability of bioactive ingredients, restricts our ability to identify the most effective dietary regimes to improve platelet function. Implementation of uniform point-of-care tests to assess platelet function, and enhanced knowledge of the efficacy by which specific dietary compounds and their metabolites affect platelet function, may enable the identification of functional anti-platelet ingredients that are eligible for a health claim, or combined treatment strategies, including both pharmacological anti-platelet treatment as well as dietary intervention, to tackle atherothrombotic vascular disease.

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.

Stereospecific analysis of triacylglycerol and phospholipid fractions of five wild freshwater fish from Poyang Lake

The fatty acids (FA) compositions and positional distributions in triacylglycerols (TAG) and phospholipids (PL) of five wild freshwater fish (Squaliobarbus curriculus, Erythroculter ilishaeformis, Pseudobagrus fulvidraco, Bostrichthys sinensis, and Siniperca kneri Garman) from Poyang Lake (the largest freshwater lake of China) were studied. For TAG, S. kneri German had the highest content (13.59%) of n - 3 polyunsaturated fatty acids (PUFA) and E. ilishaeformis had the lowest ratio of (n - 6)/(n - 3) (0.65). PL had a high content of PUFA, which declined in the order of phosphatidylethanolamine (PE) > phosphatidylcholine (PC) > TAG. 9c11t-18:2 accounted for 6.38-50.77% of total conjugated linoleic acids (CLA). The highest level of odd-branched chain fatty acids (OBCFA) was 26.7% in B. sinensis. The study revealed that the distribution of FA among the sn positions was not random: monounsaturated fatty acids (MUFA) and PUFA preferred positions 1 and 3 and saturated fatty acids (SFA) position 2 of TAG, while SFA and MUFA predominated over sn-1-PL and PUFA over sn-2-PL.

The optimal male health diet and dietary supplement program

The primary cause of mortality in most developed countries is cardiovascular disease, which is the primary cause of death in the largest clinical studies of male health conditions. There are simplistic correlations between heart health and male-specific diseases. Clinicians need to motivate and provide a simplistic and realistic set of lifestyle, dietary supplement, and prescription drug recommendations to men to affect all-cause morbidity and mortality. This article provides recommendations to assist the clinician and patient to make practical changes that may be accomplished in a short period of time, and should provide tangible overall benefit for men's health.

Omega-3 polyunsaturated Fatty acids and heart rate variability

Omega-3 polyunsaturated fatty acids (PUFA) may modulate autonomic control of the heart because omega-3 PUFA is abundant in the brain and other nervous tissue as well as in cardiac tissue. This might partly explain why omega-3 PUFA offer some protection against sudden cardiac death (SCD). The autonomic nervous system is involved in the pathogenesis of SCD. Heart rate variability (HRV) can be used as a non-invasive marker of cardiac autonomic control and a low HRV is a predictor for SCD and arrhythmic events. Studies on HRV and omega-3 PUFA have been performed in several populations such as patients with ischemic heart disease, patients with diabetes mellitus, patients with chronic renal failure, and in healthy subjects as well as in children. The studies have demonstrated a positive association between cellular content of omega-3 PUFA and HRV and supplementation with omega-3 PUFA seems to increase HRV which could be a possible explanation for decreased risk of arrhythmic events and SCD sometimes observed after omega-3 PUFA supplementation. However, the results are not consistent and further research is needed.

Effects of supplementation with polyunsaturated fatty acids in patients with heart failure

Despite the clinical and prognostic improvement obtained with the current medical treatment, heart failure (HF) continues to have high morbidity and mortality and its prevalence is increasing in most regions of the world. Thus, there is a need for novel adjunctive therapies that act independently of current neurohormonally and haemodynamically oriented drugs. Nutritional approaches are particularly attractive because they could work additively with established therapies without negative hemodynamic effects. There is growing evidence that omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplementation positively impacts established pathophysiological mechanisms in HF and thus has a potential role for preventing and treating HF. The results of the GISSI-HF trial have indicated that, in patients with chronic HF on evidence-based therapy, long term treatment with PUFAs reduced mortality and hospitalizations for cardiovascular reasons, irrespective of etiology and left ventricular (LV) ejection fraction (EF). The purpose of this review is to summarize the evidence emerged from studies conducted so far on the effect of n-3 PUFAs in HF.

Uses and benefits of omega-3 ethyl esters in patients with cardiovascular disease

Much evidence on the favorable effects of omega-3 ethyl esters on cardiovascular morbidity and mortality has been obtained in studies performed in healthy subjects and in different clinical settings. Here the clinical effects of omega-3 ethyl ester administration in patients with previous myocardial infarction or heart failure are reviewed, together with a discussion of underlying mechanisms of action. The pharmacokinetic and pharmacodynamic properties of omega-3 ethyl esters, as well as evidence concerning their safety and tolerability, are also reported.

Cardiac mortality is associated with low levels of omega-3 and omega-6 fatty acids in the heart of cadavers with a history of coronary heart disease

The benefits of omega-3 (ie, eicosapentaenoic acid and docosahexaenoic acid [DHA]) and omega-6 (ie, linoleic acid and arachidonic acid [AA]) fatty acids on reducing cardiac mortality are still debated. In this study, we tested the hypothesis that high levels of omega-3 and omega-6 fatty acids in heart tissues are associated with low cardiac mortality in Thai cadavers. One hundred fresh cadavers were examined in this study. The cause of death, history of coronary heart disease (CHD), and fish consumption habits were obtained from death certificates, cadaver medical record profiles, and a questionnaire to a person who lived with the subject before death. In each cadaver, biopsies of cardiac tissues were taken from the interventricular septum for measurement of fatty acid. Of the 100 cadavers (average age, 69 +/- 13 years), 60 were men. The frequency of fish consumption was directly associated with omega-3 and omega-6 fatty acids in heart tissues (P < .01). History of CHD and cause of death (cardiac vs noncardiac) were not significantly associated with levels of omega-3 or omega-6 fatty acids. However, in cadavers with a history of CHD, high levels of omega-3 and omega-6, particularly DHA and AA, were associated with low cardiac mortality (P < .05). Fish consumption is associated with levels of omega-3 and omega-6 fatty acids in heart tissues. Although omega-3 and omega-6 fatty acids are not associated with cardiac mortality in the overall studied population, their low levels (especially DHA and AA) in heart tissues are associated with high cardiac mortality in cadavers with a history of CHD.

Elevated heart rate in cardiovascular diseases: a target for treatment?

Heart rate is a major determinant of myocardial oxygen consumption and of cardiac work, and thus reduction of heart rate may represent an important strategy for the treatment of patients with a wide range of cardiac disorders. In addition, several experimental lines of research point to high heart rate as an important risk factor for atherosclerosis and, thus, pharmacologic heart rate reduction could prevent or retard the development of atherosclerotic plaques and increase survival. Today, in patients with acute or chronic coronary syndromes or with congestive heart failure, reducing heart rate is a generally accepted treatment modality. Up to now, no human study has been performed to demonstrate the efficacy and the risk-benefit ratio of cardiac slowing in patients without cardiac disorders. However, recent retrospective analyses of the INternational VErapamil-SR/trandolapril STudy and the Paris Prospective Study 1 provided promising results. Treatment of high heart rate in healthy subjects appears to be premature, but in clinical conditions such as hypertension or diabetes, the reduction of elevated heart rate appears a desirable additional goal of therapy.

Efficacy and safety of prescription omega-3-acid ethyl esters for the prevention of recurrent symptomatic atrial fibrillation: a prospective study

BACKGROUND

Atrial fibrillation (AF) continues to be one of the most common cardiac problems, placing an expanding burden on the public health system. In several circumstances, AF can increase the risk of stroke and heart failure. Current pharmacologic treatment options are associated with the potential for significant adverse events, which often outweigh the benefits of achieving sinus rhythm. There is evidence to suggest antiarrhythmic benefits of omega-3 polyunsaturated fatty acids; however, the data are not conclusive. This study is designed to further assess the effect of prescription omega-3 ethyl esters (P-OM3) in the prevention of recurrent AF in patients with AF without (significant) structural heart disease.

METHODS

This trial is a 6-month randomized, double-blind, placebo-controlled, parallel-study design. Patients with confirmed symptomatic paroxysmal or persistent AF (5:1 ratio) will be randomized to receive either 4 g/d P-OM3 (Lovaza; GlaxoSmithKline, Research Triangle Park, NC) or placebo. The primary end point is the first recurrence of symptomatic AF among patients with paroxysmal AF. Secondary end points include the first recurrence of symptomatic AF among all patients. Safety will be assessed regularly.

CONCLUSION

This is the first randomized blinded trial to assess the antiarrhythmic effects of 4 g/d P-OM3 in paroxysmal AF.

Artificial rearing of infant mice leads to n-3 fatty acid deficiency in cardiac, neural and peripheral tissues

The ability to control the fatty acid content of the diet during early development is a crucial requirement for a one-generation model of docosahexaenoic acid (DHA; 22:6n3) deficiency. A hand feeding method using artificial rearing (AR) together with sterile, artificial milk was employed for feeding mice from postnatal day 2-15. The pups were fed an n-3 fatty acid adequate (3% alpha-linolenic acid (LNA; 18:3n3) + 1% 22:6n3) or a deficient diet (0.06% 18:3n3) with linoleic acid (LA; 18:2n6) as the only dietary source of essential fatty acids by AR along with a dam-reared control group (3.1% 18:3n3). The results indicate that restriction of n-3 fatty acid intake during postnatal development leads to markedly lower levels of brain, retinal, liver, plasma and heart 22:6n3 at 20 weeks of age with replacement by docosapentaenoic acid (DPAn6; 22:5n6), arachidonic acid (ARA; 20:4n6) and docosatetraenoic acid (DTA; 22:4n6). A detailed analysis of phospholipid classes of heart tissue indicated that phosphatidylethanolamine, phosphatidylcholine and cardiolipin were the major repositories of 22:6n3, reaching 40, 29 and 15%, respectively. A novel heart cardiolipin species containing four 22:6n3 moieties is described. This is the first report of the application of artificially rearing to mouse pup nutrition; this technique will facilitate dietary studies of knockout animals as well as the study of essential fatty acid (EFA) functions in the cardiovascular, neural and other organ systems.

Long-chain n-3 polyunsaturated fatty acids: new insights into mechanisms relating to inflammation and coronary heart disease

Evidence from observational studies, prospective cohort studies and randomized clinical intervention studies indicate that moderate doses of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) significantly decrease risk of fatal coronary heart disease (CHD). Higher doses and longer duration of intervention may also protect from non-fatal CHD events. The exact mechanisms through which LC n-3 PUFA has an effect on CHD are not well established but may include a decrease in fasting and postprandial triacylglycerol levels, a decrease in arrhythmias, modulation of platelet aggregation and decreased synthesis of pro-inflammatory agents. The mechanistic relation between LC n-3 PUFA and inflammation has attracted great interest, and in vitro studies have revealed that these fatty acids decrease endothelial activation, affect eicosanoid metabolism (including epoxygenation pathways) and induce inflammatory resolution. However, the effects of LC n-3 PUFA on established biomarkers of inflammation and endothelial activation in vivo are not strong. Consequently we need new and more sensitive and systemic biomarkers to reveal the effects of LC n-3 PUFA on localized inflammatory processes.

Omega-3 fatty acids and the cardiometabolic syndrome

Benefits of fish consumption in patients with the cardiometabolic syndrome relate to the high biologic value of protein, omega-3 fatty acids, as well as certain minerals and vitamins in fish. Recently, the American Heart Association issued new guidelines for the intake of omega-3 oils for the prevention of coronary heart disease. The objective of this paper is to evaluate the potential health benefits of fish consumption and/or fish oil supplements in reducing cardiometabolic syndrome risk factors. The consumption of fish or fish oil containing omega-3 polyunsaturated fatty acids reduces the risk of coronary heart disease, decreases triglyceride, blood pressure, and inflammatory markers, improves endothelial function, prevents certain cardiac arrhythmias, reduces platelet aggregation (including reactivity and adhesion), reduces vasoconstriction, enhances fibrinolysis, reduces fibrin formation, and decreases the risk of microalbuminuria and sudden cardiac death. Thus, fish intake or fish oil supplement use is beneficial to reduce cardiometabolic risk factors.

Omega-3 fatty acids: how can they be used in secondary prevention?

Omega-3 fatty acids (FAs) are divided into long-chain fatty acids (eicosapentaenoic acid and docosahexaenoic acid ), which are found in fatty fish, and intermediate-chain FAs (alpha-linolenic acid), which are found in vegetable oils. Omega-3 FAs favorably modulate a variety of vascular risk factors and also exert antiarrhythmic effects. Epidemiologic data suggest that increased consumption of marine omega-3 FAs is associated with reduced coronary heart disease (CHD) mortality. Randomized controlled studies also show that supplementation with EPA and DHA reduces CHD risk, primarily in the secondary prevention setting. Data are more limited on the efficacy of marine omega-3 FAs for the primary prevention of CHD and on the role of alpha-linolenic acid. Increased intake of EPA and DHA represents a valuable tool for vascular disease prevention and should be recommended in all patients with CHD.

The role of n-3 PUFAs in preventing the arrhythmic risk in patients with idiopathic dilated cardiomyopathy

BACKGROUND

N-3 polyunsaturated fatty acids (n-3 PUFAs) intake is associated with a reduction in sudden cardiac death in patients with ischemic heart disease. Their effects in patients with heart failure caused by idiopathic dilated cardiomyopathy (IDC) are unknown.

METHODS

We compared with placebo the effects of n-3 PUFAs administration in 44 patients with IDC and with frequent or repetitive ventricular arrhythmias at Holter monitoring using a randomized, double-blind design. Arrhythmic risk was assessed by microvolt T-wave analysis (MTWA), signal averaged ECG (SAECG), Holter monitoring, power spectral analysis of heart rate (HR) variability, catecholamine and cytokine plasma levels, at baseline and after 6 months.

RESULTS

At MTWA, 7/12 patients (58%) initially positive became negative after n-3 PUFAs while one patient became positive after placebo (p = 0.019). N-3 PUFAs administration was also associated to normalization of SAECG (11/15 patients, p < 0.0015), decrease in non-sustained ventricular tachycardia (NSVT) episodes (p = 0.0002) and NSVT HR (p = 0.0003), improvement in HR variability and decrease in catecholamine and cytokine plasma levels. The ratio of plasma n-6 PUFAs to n-3 PUFAs decreased from 12.01 to 3.48 after n-3 PUFAs.

CONCLUSIONS

N-3 PUFAs administration is associated with favorable effects on parameters related to arrhythmic risk in patients with idiopathic dilated cardiomyopathy. These results are consistent with antiarrhythmic activity independent from their antiischemic effects.

Docosahexaenoic acid-rich fish oil improves heart rate variability and heart rate responses to exercise in overweight adults

Dietary fish oil supplementation and regular physical activity can improve outcomes in patients with established CVD. Exercise has been shown to improve heart rate variability (HRV), a predictor of cardiac death, but whether fish oil benefits HRV is controversial. Obese adults at risk of future coronary disease have impaired HRV and may benefit from these interventions. We evaluated the effect of DHA-rich tuna fish oil supplementation with and without regular exercise on HRV in sedentary, overweight adults with risk factors for coronary disease. In a randomised, double-blind, parallel comparison, sixty-five volunteers consumed 6 g fish oil/d (DHA 1·56 g/d, EPA 0·36 g/d) or sunflower-seed oil (placebo) for 12 weeks. Half of each oil group also undertook regular moderate physical activity (3 d/week for 45 min, at 75 % of age-predicted maximal heart rate (HR)). Resting HR and the HR response to submaximal exercise were measured at weeks 0, 6 and 12. In forty-six subjects, HRV was also assessed by power spectrum analysis of 20 min electrocardiogram recordings taken supine at baseline and 12 weeks. Fish oil supplementation improved HRV by increasing high-frequency power, representing parasympathetic activity, compared with placebo (P = 0·01; oil ×  time interaction). It also reduced HR at rest and during submaximal exercise (P = 0·008; oil ×  time interaction). There were no significant fish oil ×  exercise interactions. Dietary supplementation with DHA-rich fish oil reduced HR and modulated HRV in keeping with an improved parasympathetic–sympathetic balance in overweight adults with risk factors for future coronary disease.

Effects of fatty and lean fish intake on blood pressure in subjects with coronary heart disease using multiple medications

BACKGROUND

Intake of fish and long-chain n-3 fatty acids has been of wide interest due to their beneficial effects on cardiovascular risk factors and lower coronary heart disease (CHD) risk.

AIM OF THE STUDY

The aim of this pilot study was to examine the effects of fatty fish and lean (white) fish on fatty acid composition of serum lipids and cardiovascular risk factors in subjects with CHD using multiple drugs for this condition.

METHODS

The study was an 8-week controlled, parallel intervention. Inclusion criteria were myocardial infarction or unstable ischemic attack, age under 70 years, use of betablockers and presence of sinus rhythm. The subjects were randomized to one of the following groups: 4 meals/week fatty fish (n = 11), 4 meals/week lean fish (n = 12) and control diet including lean meat (n = 10).

RESULTS

The mean (+/-SD) of reported fish meals per week was 4.3 +/- 0.4, 4.7 +/- 1.1 and 0.6 +/- 0.4 in the groups, respectively. The proportions of eicosapentaenoic and docosahexaenoic acids in serum lipids increased in the fatty fish group only (P < 0.05). Systolic and diastolic blood pressure levels decreased in the lean fish group (0 vs. 8 week: 3.5 +/- 3.2 and 4.6 +/- 3.6%, respectively, P < 0.05). Serum total triglyceride concentration did not significantly change. HDL cholesterol concentration change differed among groups but without significant post hoc differences. Apolipoprotein A-1 concentration decreased in the control group (0 vs. 8 week, P < 0.05). Coagulation factors, 25-hydroxy vitamin D, and heart rate variability (24 h Holter) did not change among the groups.

CONCLUSIONS

Our results suggest that intake of lean fish at least four times per week could reduce blood pressure levels in CHD patients.

New approaches to therapy with omega-3 fatty acids

With greater focus on chronic disease prevention, renewed attention has been directed toward understanding the pathophysiology of various medical conditions and the development of newer medical treatments to prevent and treat complications. There has been immense interest in evaluating societal lifestyles, cultural attitudes toward health, and dietary influences on health conditions. The omega-3 fatty acids have become a focus of interest, and recent research and trial evidence have highlighted their effects, including potential clinical advantages. Despite this progress, the precise mechanisms through which omega-3 fatty acids act remain poorly understood. These agents are now recommended as secondary prevention after acute myocardial infarction, and ongoing large clinical trials should provide insight into the use of omega-3 fatty acids in heart failure and the primary prevention of cardiovascular disease.

n-3 PUFAs-From dietary supplements to medicines

Although there has been a great progress in the prevention of cardiovascular diseases, the mortality of patients with acute myocardial infarction (AMI) still remains high. One of the most important underlying causes explaining this phenomenon is the sudden cardiac death. Nearly half of all cardiovascular deaths in the USA each year is attributed to this unpredictable and unexpected complication of AMI. Hence, there is an urgent medical need for a targeted therapy to reduce the incidence of sudden cardiac death. Since 1980 there have been several epidemiological and other studies concerning the benefits of n-3 polyunsaturated fatty acids (n-3 PUFAs) in cardiovascular health and prevention. Results from one of the largest studies, GISSI Prevenzione Trial show that adding the n-3 PUFAs to standard therapy of patients who survived AMI reduces sudden cardiac death (44% risk reduction, p=0.0006). In addition, significant decline in all-cause cardiovascular mortality (21% risk reduction, p=0.0064) further emphasizes the role of n-3 PUFA in cardiovascular prevention. To date, beneficial effects of n-3 PUFA are attributed to their antiarrhythmic, lipid lowering, antithrombotic and anti-inflammatory properties. To conclude, EPA and DHA improve the prognosis of cardiovascular patients in the secondary prevention of sudden cardiac death without any documented side effects.

Oral omega n3-PUFA therapy (Omacor) has no impact on indices of heart rate variability in stable post myocardial infarction patients

OBJECTIVE

To determine the effects of n3-PUFA supplementation, in the dose used in the GISSI-Prevenzione study, on indices of heart rate variability (HRV) in patients following myocardial infarction (AMI).

MATERIALS AND METHODS

Open label randomised single blind controlled trial. Thirty eight patients post AMI, stable on standard secondary prevention drug therapy were single blind randomised to receive either Omacor 1 g/day (n = 21) or usual care (n = 17). HRV indices (time and frequency-domain) were measured at baseline and following 3 months of treatment.

RESULTS

At baseline there were no significant differences in clinical, biochemical or HRV indices between patient groups. After 3 months therapy there were no observed changes in measured HRV indices in either the Omacor supplemented or 'usual care' groups.

CONCLUSIONS

Three month supplementation of omega 3 PUFA (Omacor) 1 g/day has no effect on HRV is patients post AMI.

Longchain n-3 polyunsaturated fatty acids and microvascular reactivity: Observation in the hamster cheek pouch

Previous experiments in our laboratory, using the hamster cheek pouch microcirculation, have shown that precapillary vessels exhibit spontaneous rhythmic luminal variations, termed vasomotion, a myogenic activity sustained by a balance between membrane currents among which polarizing K(+) currents play an important role. In these microvessels, endothelium-derived relaxing factors (EDRFs) seem to regulate arteriolar diameter [via nitric oxide (NO) and cyclic GMP] and vasomotion [probably via endothelium-derived hyperpolarizing factor (EDHF)]. Fish or fish oil diet can decrease the risk of cardiovascular diseases, probably by modifying the conductance of selective ion channels, such as K(+) and/or Ca(++), and/or increasing the production of vasodilators, such as NO. To investigate its effect on microvascular reactivity, using the same preparation and an intravital microscope coupled to a closed circuit TV system, male hamsters were treated for 14 days, twice a day, with 0.4 mL/100 g body weight with fish or olive oil. An attempt was also undertaken to record in arterioles, in vivo, the membrane potential of smooth muscle cells during their vasomotor activity combining conventional microelectrode and intravital microscopy techniques. The effects of topical application of two vasodilators, acetylcholine [endothelium-dependent one, NO release and membrane hyperpolarization via Ca(++)-activated K(+) channels (K(Ca))] and sodium nitroprusside (endothelium-independent, NO donor and no change on membrane potential) and two vasoconstrictors which elicited membrane depolarization via Ca(++) channels, phenylephrine (alpha(1)-adrenergic receptor agonist) and serotonin (5-hydroxi-tryptamine) on mean internal diameter of arterioles and venules, arteriolar blood flows, spontaneous arteriolar vasomotion frequency and amplitude and functional capillary density (FCD, number of capillaries with flowing red blood cells per unit area of tissue) were determined. Anesthesia was induced by sodium pentobarbital (i.p.) and maintained with alpha-chloralose through the femoral vein. In the presence of vasomotion, the membrane potentials are slowly oscillating by about 20 mV around values of approximately -50 mV in perfect synchrony with vasomotor movements and depolarizing phases coincide with vasoconstrictions while polarizing ones with vasodilatations. Comparing all parameters, in control conditions, only the spontaneous vasomotion frequency was significantly higher (2.37 times higher) on the group treated with fish oil and persisted as such throughout all experiments. With topical application of the drugs mentioned above, the group treated with fish oil showed, for each drug concentration, a balance towards vasodilatation with consequent increase on arteriolar blood flow and on FCD, compared with the olive oil treated one. No significant changes on mean arterial pressure, spontaneous arteriolar vasomotion amplitude or venular diameter could be detected in the two groups. Our results support the concept that, in the hamster cheek pouch microcirculation, fish oil supplementation activates K(+) channels which act as the EDHF and might also increase the production of vasodilators, probably NO.

Long-term fish consumption is associated with protection against arrhythmia in healthy persons in a Mediterranean region--the ATTICA study

BACKGROUND

Dietary habits have long been associated with many manifestations of cardiovascular disease.

OBJECTIVE

We sought to investigate whether a diet enriched with fish and n-3 fatty acid consumption are associated with changes in the potential duration of the electrical action, as represented by the QT duration on a resting electrocardiogram, in a population-based sample of Greek adults.

DESIGN

During 2001 and 2002, we randomly enrolled 1514 men (18-87 y old) and 1528 women (18-89 y old) stratified by age and sex distribution (in the 2001 Greek census) from the Attica area, Greece. We studied several demographic, anthropometric, lifestyle, dietary, and bioclinical factors of the participants. Dietary habits (including fish consumption) were evaluated by using a validated food-frequency questionnaire. All subjects underwent electrocardiography with a 12-lead surface, in which, along with several other indexes, QT duration was measured, and the heart rate-corrected QT (QTc) was calculated (corrected by using Bazett's rate). The tested hypothesis was evaluated through multiple linear regression analysis, after control for physical activity status, sex, age, medication intake, and several other potential confounders.

RESULTS

Compared with fish nonconsumers, those who consumed >300 g fish/wk had a mean 13.6% lower QTc (P<0.01). These findings were confirmed after adjustment for age, sex, physical activity status, BMI, smoking habits, intake of nuts, and other confounders. Moreover, compared with fish nonconsumers, those who consumed >or=300 g fish/wk had a 29.2% lower likelihood of having QTc intervals >0.45 s (P=0.03).

CONCLUSIONS

Long-term consumption of fish is associated with lower QTc interval in free-eating people without any evidence of cardiovascular disease. Thus, fish intake seems to provide antiarrhythmic protection at a population level.

Highly Purified Omega-3 Fatty Acids for Secondary Prevention of Sudden Cardiac Death After Myocardial Infarction—Aims and Methods of the OMEGA-Study

INTRODUCTION

During the last decades a large body of data has been accumulated indicating omega-3 fatty acids to exert beneficial effects on the prognosis of patients with cardiovascular disease. Especially, omega-3 fatty acids are regarded to be effective in reducing the risk of sudden cardiac death after acute myocardial infarction. However, treatment of acute myocardial infarction and secondary prevention considerably have been improved within the past years including early revascularization by PCI, the routine use of beta-blockers, statins and ACE-inhibitors as well as cardiac rehabilitation for improving life style measures. To date, there exists no controlled randomized trial testing the prognostic effect of omega-3 fatty acids after acute myocardial infarction in a double blind regimen under the conditions of modern treatment of myocardial infarction.

MATERIALS AND METHODS

The present study therefore evaluates the effect of highly purified omega-3 fatty acid ethylesters (omega-3-acid ethyl esters 90=Zodin) on the rate of sudden cardiac death within 1 year after acute myocardial infarction. Secondary endpoints are total mortality, non-fatal cardiovascular events, rhythm abnormalities in holter monitoring and depression score.

RESULT AND CONCLUSION

The recruitment-period started in October 2003 and is expected to last until December 2006. The results of the study are therefore expected for the beginning of 2008, when all patients will have completed the 12-months follow up-period.

Antiarrhythmic effects of omega-3 fatty acids

Fish oil, and omega-3 fatty acids in particular, have been found to reduce plasma levels of triglycerides and increase levels of high-density lipoprotein in patients with marked hypertriglyceridemia, and a pharmaceutical-grade preparation has recently received approval from the US Food and Drug Administration to market for this purpose. However, in both bench research studies and clinical trials, evidence for clinically significant antiarrhythmic properties has also been detected in association with omega-3 fatty acid intake. Arguably the most significant finding in this data set was the reduction in the incidence of sudden death in survivors of myocardial infarction in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione trial and the subsequent recommendation for administration of fish oil as part of the postinfarction regimen in Europe. This article reviews in detail the basic and clinical research studies of fish oil as an antiarrhythmic entity, the forms of preparation and/or administration that appear to possess these properties and those that do not, the types of arrhythmias (ventricular ectopy and atrial fibrillation as well as ventricular tachyarrhythmias) that have been beneficially affected by fish oil administration, and the presumed and known mechanisms by which the beneficial actions are exerted.