A meta-analysis of omega-3 fatty acids and incidence of atrial fibrillation

Mediterranean Diet: A Tool to Break the Relationship of Atrial Fibrillation with the Metabolic Syndrome and Non-Alcoholic Fatty Liver Disease

Atrial fibrillation (AF) is the most common supraventricular arrhythmia associated with increased cardiovascular and non-cardiovascular morbidity and mortality. As multiple factors may predispose the onset of AF, the prevention of the occurrence, recurrence and complications of this arrhythmia is still challenging. In particular, a high prevalence of cardio-metabolic comorbidities such as the metabolic syndrome (MetS) and in its hepatic manifestation, the non-alcoholic fatty liver disease (NAFLD), have been described in the AF population. A common pathogenetic mechanism linking AF, MetS and NAFLD is represented by oxidative stress. For this reason, in the past decades, numerous studies have investigated the effect of different foods/nutrients with antioxidant properties for the prevention of, and their therapeutic role is still unclear. In this narrative comprehensive review, we will summarize current evidence on (1) the association between AF, MetS and NAFLD (2) the antioxidant role of Mediterranean Diet and its components for the prevention of AF and (3) the effects of Mediterranean Diet on MetS components and NAFLD.

Dose-response effects of omega-3 on platelet aggregation: an observational study

OBJECTIVE

This study aimed to evaluate the dose-response effects of supplemental omega-3 fatty acids on platelet function in healthy volunteers.

METHODS

Twelve healthy volunteers ingested a normal supplemental dose of 1260 mg omega-3 fatty acids daily for 5 days, followed by a high dose of 2520 mg daily for another 5 days. Multiple electrode aggregometry (MEA) with four different agonists was used to measure platelet aggregation before and after the normal- and high-dose regimes. In vitro spiking using physiological doses of omega-3 fatty acids was also performed to determine whether MEA is capable of detecting a platelet-inhibiting effect due to omega-3 fatty acids.

RESULTS

There were no differences in platelet aggregation measured by the MEA assay in healthy volunteers after intake of either the normal or high dose of omega-3 fatty acids. In the in vitro experiment, a platelet-inhibiting effect of omega-3 fatty acids was shown by an arachidonic acid agonist in MEA .

CONCLUSIONS

Supplemental omega-3 fatty acids do not evoke their positive health effects through inhibition of platelet aggregation measurable with MEA.

DietaryFish and Long-Chain n-3 Polyunsaturated Fatty Acids Intake and Risk of Atrial Fibrillation: A Meta-Analysis

Findings on the association between long-term intake of fish or long-chain n-3 polyunsaturated fatty acids (PUFAs) and risk of atrial fibrillation (AF) are inconsistent in observational studies. We conducted a meta-analysis of prospective studies to separately examine the associations between fish consumption and dietary intake of n-3 PUFAs with the risk of AF. A systematic search was conducted in PubMed and Embase to identify relevant studies. Risk estimates were combined using a random-effect model. Seven prospective cohort studies covering 206,811 participants and 12,913 AF cases were eligible. The summary relative risk of AF for the highest vs. lowest category of fish consumption and dietary intake of n-3 PUFAs was 1.01 (95% confidence interval: 0.94–1.09) and 1.03 (95% confidence interval: 0.97–1.09), respectively. These null associations persisted in subgroup and dose-response analyses. There was little evidence of publication bias. This meta-analysis suggests that neither long-term intake of fish, nor of n-3 PUFAs were significantly associated with lower risk of AF.

Upstream Treatment of Atrial Fibrillation with n-3 Polyunsaturated Fatty Acids: Myth or Reality?

Atrial fibrillation (AF) is the most common sustained arrhythmia in adults and is associated with an increased risk of fatal and non-fatal events. Antiarrhythmic drugs provide limited protection against AF recurrence and have a poor safety profile. Several mechanisms have been proven to be involved in AF, e.g. inflammation, oxidative stress, fibrosis and ischaemia. Prevention of AF with interventions that target these mechanisms has emerged as a result of experimental studies suggesting the use of upstream therapies. Long chain n-3 polyunsaturated fatty acids (n-3 PUFA) have multiple effects on cardiac electrophysiology, and epidemiological studies on fish oil suggest a possible use of n-3 PUFA in AF prevention. Several randomised clinical trials have been designed to evaluate the efficacy of n-3 PUFA in preventing AF. In this review, we report the conflicting results of these trials in two different clinical settings: recurrence in patients with history of AF and development of post-operative AF in patient undergoing cardiac surgery.

N-3 fatty acids for prevention of cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death in the USA. A diet enriched with n-3 fatty acids (FA) has been reported to play an important role in preventing the development of CVD. Prior studies have demonstrated beneficial effects of n-3 FA on hypertriglyceridemia, blood pressure, inflammation, endothelial function, and platelet function. However, data on the relation of n-3 FA consumption with CVD risk remain inconsistent. This paper reviews current evidence on the effects of n-3 FA on CVD, CVD risk factors, and potential biologic mechanisms. Last, we discuss major limitations of currently available data and future directions in the field.

Long-chain omega-3 fatty acids: time to establish a dietary reference intake

The beneficial effects of consuming omega-3 polyunsaturated fatty acids (n-3 PUFAs), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on cardiovascular health have been studied extensively. To date, there is no dietary reference intake (DRI) for EPA and DHA, although many international authorities and expert groups have issued dietary recommendations for them. Given the substantial new evidence published since the last Institute of Medicine (IOM) report on energy and macronutrients, released in 2002, there is a pressing need to establish a DRI for EPA and DHA. In order to set a DRI, however, more information is needed to define the intakes of EPA and DHA required to reduce the burden of chronic disease. Information about potential gender- or race-based differences in requirements is also needed. Given the many health benefits of EPA and DHA that have been described since the 2002 IOM report, there is now a strong justification for establishing a DRI for these fatty acids.

Do Omega-3 Fatty Acids Decrease the Incidence of Atrial Fibrillation?

Although atrial fibrillation is a very common medical problem in general population and has a high incidence in the setting of open heart surgery, there are very few therapies to prevent occurrence or recurrence of atrial fibrillation. N-3 polyunsaturated fatty acids have been shown to change basic physiologic properties of the atrial tissue to make it less susceptible to atrial fibrillation. In this review, we first describe basic physiological mechanisms thought to be responsible for these changes and then discuss observational and interventional studies evaluating the use n-3 polyunsaturated fatty acids for primary and secondary prevention of atrial fibrillation in the general population, in subjects undergoing open heart surgery, and in special subgroups of patients.

The effects of omega-3 polyunsaturated fatty acids on cardiac rhythm: a critical reassessment

Although epidemiological studies provide strong evidence for an inverse relationship between omega-3 polyunsaturated fatty acids (n-3 PUFAs) and cardiac mortality, inconsistent and often conflicting results have been obtained from both animal studies and clinical prevention trials. Despite these heterogeneous results, some general conclusions can be drawn from these studies: 1) n-PUFAs have potent effects on ion channels and calcium regulatory proteins that vary depending on the route of administration. Circulating (acute administration) n-3 PUFAs affect ion channels directly while incorporation (long-term supplementation) of these lipids into cell membranes indirectly alter cardiac electrical activity via alteration of membrane properties. 2) n-3 PUFAs reduce baseline HR and increase HRV via alterations in intrinsic pacemaker rate rather than from changes in cardiac autonomic neural regulation. 3) n-3 PUFAs may be only effective if given before electrophysiological or structural remodeling has begun and have no efficacy against atrial fibrillation. 5) Despite initial encouraging results, more recent clinical prevention and animal studies have not only failed to reduce sudden cardiac death but actually increased mortality in angina patients and increased rather than decreased malignant arrhythmias in animal models of regional ischemia. 6) Given the inconsistent benefits reported in clinical and experimental studies and the potential adverse actions on cardiac rhythm noted during myocardial ischemia, n-3 PUFA must be prescribed with caution and generalized recommendations to increase fish intake or to take n-3 PUFA supplements need to be reconsidered.

The Role of Essential Fatty Acids in Human Health

Fatty acid research began about 90 years ago but intensified in recent years. Essential fatty acids (linoleic and α-linolenic) must come from diet. Other fatty acids may come from diet or may be synthesized. Fatty acids are major components of cell membrane structure, modulate gene transcription, function as cytokine precursors, and serve as energy sources in complex, interconnected systems. It is increasingly apparent that dietary fatty acids influence these vital functions and affect human health. While the strongest evidence for influence is found in cardiovascular disease and mental health, many additional conditions are affected. Problematic changes in the fatty acid composition of human diet have also taken place over the last century. This review summarizes current understanding of the pervasive roles of essential fatty acids and their metabolites in human health.

N-3 polyunsaturated fatty acids to prevent atrial fibrillation: updated systematic review and meta-analysis of randomized controlled trials

Background

Previous studies have suggested that n‐3 polyunsaturated fatty acids (n‐3 PUFAs) have antiarrhythmic effects on atrial fibrillation (AF). We aimed to assess the effects of therapy with n‐3 PUFAs on the incidence of recurrent AF and on postoperative AF.

Methods and Results

Electronic searches were conducted in Web of Science, Medline, Biological Abstracts, Journal Citation Reports, and the Cochrane Central Register of Controlled Trials databases. In addition, data from the recently completed FORωARD and OPERA trials were included. We included randomized controlled trials comparing treatment with n‐3 PUFAs versus control to (1) prevent recurrent AF in patients who underwent reversion of AF or (2) prevent incident postoperative AF after cardiac surgery. Of identified studies, 12.9% (16 of 124) were included, providing data on 4677 patients. Eight studies (1990 patients) evaluated n‐3 PUFA effects on AF recurrence among patients with reverted AF and 8 trials (2687 patients) on postoperative AF. Pooled risk ratios through random‐effects models showed no significant effects on AF recurrence (RR, 0.95; 95% CI, 0.79 to 1.13; I², 72%) or on postoperative AF (0.86; 95% CI, 0.71 to 1.04; I², 53.1%). A funnel plot suggested publication bias among postoperative trials but not among persistent AF trials. Meta‐regression analysis did not find any relationship between doses and effects (P=0.887 and 0.833 for recurrent and postoperative AF, respectively).

Conclusions

Published clinical trials do not support n‐3 PUFAs as agents aimed at preventing either postoperative or recurrent AF.

Clinical Trial Registration

URL: http://www.crd.york.ac.uk/PROSPERO. Unique Identifier: CRD42012002199.

Fish oil and postoperative atrial fibrillation: the Omega-3 Fatty Acids for Prevention of Post-operative Atrial Fibrillation (OPERA) randomized trial

CONTEXT

Postoperative atrial fibrillation or flutter (AF) is one of the most common complications of cardiac surgery and significantly increases morbidity and health care utilization. A few small trials have evaluated whether long-chain n-3-polyunsaturated fatty acids (PUFAs) reduce postoperative AF, with mixed results.

OBJECTIVE

To determine whether perioperative n-3-PUFA supplementation reduces postoperative AF.

DESIGN, SETTING, AND PATIENTS

The Omega-3 Fatty Acids for Prevention of Post-operative Atrial Fibrillation (OPERA) double-blind, placebo-controlled, randomized clinical trial. A total of 1516 patients scheduled for cardiac surgery in 28 centers in the United States, Italy, and Argentina were enrolled between August 2010 and June 2012. Inclusion criteria were broad; the main exclusions were regular use of fish oil or absence of sinus rhythm at enrollment.

INTERVENTION

Patients were randomized to receive fish oil (1-g capsules containing ≥840 mg n-3-PUFAs as ethyl esters) or placebo, with preoperative loading of 10 g over 3 to 5 days (or 8 g over 2 days) followed postoperatively by 2 g/d until hospital discharge or postoperative day 10, whichever came first.

MAIN OUTCOME MEASURE

Occurrence of postoperative AF lasting longer than 30 seconds. Secondary end points were postoperative AF lasting longer than 1 hour, resulting in symptoms, or treated with cardioversion; postoperative AF excluding atrial flutter; time to first postoperative AF; number of AF episodes per patient; hospital utilization; and major adverse cardiovascular events, 30-day mortality, bleeding, and other adverse events.

RESULTS

At enrollment, mean age was 64 (SD, 13) years; 72.2% of patients were men, and 51.8% had planned valvular surgery. The primary end point occurred in 233 (30.7%) patients assigned to placebo and 227 (30.0%) assigned to n-3-PUFAs (odds ratio, 0.96 [95% CI, 0.77-1.20]; P = .74). None of the secondary end points were significantly different between the placebo and fish oil groups, including postoperative AF that was sustained, symptomatic, or treated (231 [30.5%] vs 224 [29.6%], P = .70) or number of postoperative AF episodes per patient (1 episode: 156 [20.6%] vs 157 [20.7%]; 2 episodes: 59 [7.8%] vs 49 [6.5%]; ≥3 episodes: 18 [2.4%] vs 21 [2.8%]) (P = .73). Supplementation with n-3-PUFAs was generally well tolerated, with no evidence for increased risk of bleeding or serious adverse events.

CONCLUSION

In this large multinational trial among patients undergoing cardiac surgery, perioperative supplementation with n-3-PUFAs, compared with placebo, did not reduce the risk of postoperative AF. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00970489.