Omega-3 fatty acids in the prevention of atrial fibrillation recurrences after cardioversion: a meta-analysis of randomized controlled trials

Diet and risk of atrial fibrillation: a systematic review

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia. Comprehensive modification of established AF risk factors combined with dietary interventions and breaking deleterious habits has been shown to reduce AF burden and recurrence. Numerous AF risk factors, such as diabetes, obesity or hypertension can be partially related to dietary and lifestyle choices. Therefore, dietary interventions may have potential as a therapeutic approach in AF. Based on available data, current guidelines recommend alcohol abstinence or reduction to decrease AF symptoms, burden, and progression, and do not indicate the need for caffeine abstention to prevent AF episodes (unless it is a trigger for AF symptoms). Uncertainty persists regarding harms or benefits of other dietary factors including chocolate, fish, salt, polyunsaturated and monounsaturated fatty acids, vitamins, and micronutrients. This article provides a systematic review of the association between AF and both dietary patterns and components. Additionally, it discusses potentially related mechanisms and introduces different strategies to assess patients' nutrition patterns, including mobile health solutions and diet indices. Finally, it highlights the gaps in knowledge requiring future investigation.

Omega-3 fatty acids and atrial fibrillation

Although some clinical trials have demonstrated reduced incidence of cardiovascular disease with the use of omega-3 fatty acids, others have found an increased risk of atrial fibrillation (AF). AF is the most common sustained cardiac arrhythmia worldwide. It is associated with high morbidity and mortality rates and significant public health burden. Previous studies of the effect of omega-3 fatty acids on AF occurrence have reported contradictory results. Here we reviewed the effect of omega-3 fatty acids on the risk of AF.

Association Between Omega-3 Fatty Acid Treatment and Atrial Fibrillation in Cardiovascular Outcome Trials: A Systematic Review and Meta-Analysis

PURPOSE

Data on the relationship between omega-3 fatty acid (n-3 FA) therapy with atrial fibrillation (AF) have been inconsistent. We investigate the association between n-3 FA and risk for AF by pooling data from available large, cardiovascular outcome trials.

METHODS

We performed a systematic search on PubMed and Embase for studies on n-3 FA with AF as an outcome measure. Large (≥ 1000 participants) randomized controlled trials with ≥ 1-year follow-up period were included. The association between n-3 FA and risk of AF or stroke was assessed. Mantel-Haenszel random effects model was used to calculate risk ratios (RR) with 95% confidence intervals (CI). We then performed meta-regression to evaluate effect on AF by dose of n-3 FA therapy.

RESULTS

A total of 8 randomized control trials encompassing 83,112 participants were included in the meta-analysis. Of these, five trials assessed a lower dose of n-3 FA (≤ 1 g daily, n = 61,096) while 3 trials assessed a higher dose (> 1 g daily, n = 22,016). In meta-analysis, a significant association was noted between n-3 FA treatment and risk of AF (4.0% vs 3.3%; RR 1.24, 95% CI 1.11-1.38, p = 0.0002). There was a modest but still significant association in the lower dose (n-3 FA ≤ 1 g daily) sub-group (RR 1.12, 95% CI 1.04-1.21, p = 0.004) and stronger association in the higher dose (n-3 FA > 1 g daily) sub-group (RR 1.51, 95% CI 1.26-1.80, p < 0.001; p-interaction between low versus high subgroups = 0.003). There was no increase in stroke risk (RR 1.04, 95% CI 0.90-1.20). Meta-regression demonstrated a significant association between dose of n-3 FA with risk for AF events (log RR 0.103, 95% CI 0.048-0.159, p < 0.001).

CONCLUSION

While overall AF event rates were low, n-3 FA treatment is associated with increased risk for AF.

The Efficacy of Anti-inflammatory Agents in the Prevention of Atrial Fibrillation Recurrences

Several studies have indicated an association between inflammation and the recurrence of Atrial Fibrillation (AF), especially after ablation, which is a therapeutic option leading to local inflammation. On the other hand, each AF can lead to another AF, as a general rule. Thus, preventing recurrences of AF is extremely important for patient outcomes. In this paper, we attempted to review the effect of medicinal agents with anti-inflammatory properties on the prevention of AF recurrence. There are several randomized controlled trials (RCTs) and meta-analyses on the prevention of AF recurrence using agents with anti-inflammatory properties, which include steroids, colchicine, statins, and n-3 fatty acids (n-3 FA). Clinical trials evaluating the efficacy of anti-inflammatory drugs in preventing the recurrence of AF led to inconsistent results for corticosteroids, statins and n-3 FAs. These results may be related to the fact that inflammation is not the only factor responsible for triggering recurrences of AF. For example, the presence of structural, mechanical and electrical remodeling could potentially be the most important factors that trigger recurrences of AF but these factors have not been addressed in most of the reported studies. Therefore, future clinical trials are needed to compare the efficacy of anti-inflammatory drugs in AF patients with, or without other factors. For colchicine, a potent anti-inflammatory drug, there are limited studies. However, all the studies investigating colchicine in the context of AF were consistent and promising, especially when colchicine was used on a short-term basis following ablation in patients with paroxysmal AF. Therefore, colchicine could be a promising candidate for further clinical studies involving recurrent AF.

Cardiovascular, electrophysiologic, and hematologic effects of omega-3 fatty acids beyond reducing hypertriglyceridemia: as it pertains to the recently published REDUCE-IT trial

Heart disease continues to affect health outcomes globally, accounting for a quarter of all deaths in the United States. Despite the improvement in the development and implementation of guideline-directed medical therapy, the risk of adverse cardiac events remains substantially high. Historically, it has been debated whether omega-3 polyunsaturated fatty acids provide clinical benefit in cardiac disease. The recently published REDUCE-IT trial demonstrated a statistically significant absolute risk reduction of 4.8% in its primary endpoint (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, or unstable angina) with the use of icosapent ethyl, which is a highly purified eicosapentaenoic acid (EPA) ethyl ester. However, the mechanism of action of omega-3 fatty acids is not commonly discussed. Moreover, the use of EPA was not without risk, as the incidence of atrial fibrillation was increased along with a trend towards increased bleeding risk. Thus, our aim is to help explain the function of purified EPA ethyl ester, especially at the molecular level, which will ultimately lead to a better understanding of their clinically observable effects.

A meta-analysis on Omega-3 supplements in preventing recurrence of atrial fibrillation

Previous studies had suggested that Omega-3 fatty acids have pleiotropic effects and favourable safety profile, which may potentially increase the efficacy of antiarrhythmic drugs in suppressing atrial arrhythmias through combination therapy. This meta-analysis aimed to determine the effectiveness of using Omega-3 polyunsaturated fatty acids as a sole anti-arrhythmic agent or as an adjunct to existing pharmacological therapies in preventing atrial fibrillation recurrence. Randomized controlled trials published in English, from inception to December 2016, were considered. We searched for published studies in the following electronic databases: Cochrane Central Register of Controlled Trials, PubMed, EMBASE, Medline, Scopus, and Cumulative Index to Nursing and Allied Health Literature. Pooled hazard ratio (HR) and corresponding 95% confidence intervals (CI) for time to first atrial fibrillation recurrence was analysed using a fixed effects model. Four RCTs with 1,268 participants were included in the review. Our results showed that Omega-3 polyunsaturated fatty acid therapy had no effect on preventing atrial fibrillation recurrence compared to control/placebo group (HR: 1.13, 95% CI: 0.96 to 1.33, p = 0.14), with no significant heterogeneity found among those studies (Q value = 0.15, 9 = 0.99, I² = 0%). Therefore, current evidence does not support treatment benefit of Omega-3 fatty acids in preventing atrial fibrillation recurrence among patients who have not been treated by any conventional reversion treatment, or who have only been treated with pharmacological therapy.

The Current Role of Omega-3 Fatty Acids in the Management of Atrial Fibrillation

Background: The main dietary source of omega-3 polyunsaturated fatty acids (n-3 PUFA) is fish, which contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In the present manuscript, we aimed to review the current evidence regarding the clinical role of n-3 PUFA in the prevention of atrial fibrillation (AF) and the possible underlying mechanisms. Methods: A literature search based on PubMed listings was performed using “Omega-3 fatty acids” and “atrial fibrilation” as key search terms. Results: n-3 PUFA have been shown to attenuate structural atrial remodeling, prolong atrial effective refractory period through the prevention of reentry and suppress ectopic firing from pulmonary veins. Dietary fish intake has been found to have no effect on the incidence of AF in the majority of studies. Circulating DHA has been consistently reported to be inversely associated with AF risk, whereas EPA has no such effect. The majority of studies investigating the impact of n-3 PUFA supplementation on the incidence of AF following cardiac surgery reported no benefit, though most of them did not use n-3 PUFA pretreatment for adequate duration. Studies using adequate four-week pretreatment with n-3 PUFA before cardioversion of AF showed a reduction of the AF incidence. Conclusions: Although n-3 PUFA have antiarrhythmogenic properties, their clinical efficacy on the prevention of AF is not consistently supported. Further well-designed studies are needed to overcome the limitations of the existing studies and provide robust conclusions.

The impact of omega-3 polyunsaturated fatty acid supplementation on the incidence of cardiovascular events and complications in peripheral arterial disease: a systematic review and meta-analysis

Background

Individuals with peripheral arterial disease are at higher risk for cardiovascular events than the general population. While supplementation with omega-3 polyunsaturated fatty acids (PUFA) has been shown to improve vascular function, it remains unclear if supplementation decreases serious clinical outcomes. We conducted a systematic review and meta-analysis to determine whether omega-3 PUFA supplementation reduces the incidence of cardiovascular events and complications in adults with peripheral arterial disease.

Methods

We searched five electronic databases (MEDLINE, EMBASE, CENTRAL, Scopus and the International Clinical Trials Registry Platform) from inception to 6 December 2013 to identify randomized trials of omega-3 PUFA supplementation (from fish or plant oils) that lasted ≥12 weeks in adults with peripheral arterial disease. No language filters were applied. Data on trial design, population characteristics, and health outcomes were extracted. The primary outcome was major adverse cardiac events; secondary outcomes included myocardial infarction, cardiovascular death, stroke, angina, amputation, revascularization procedures, maximum and pain-free walking distance, adverse effects of the intervention, and quality of life. Trial quality was assessed using the Cochrane Risk of Bias tool.

Results

Of 741 citations reviewed, we included five trials enrolling 396 individuals. All included trials were of unclear or high risk of bias. There was no evidence of a protective association of omega-3 PUFA supplementation against major adverse cardiac events (pooled risk ratio 0.73, 95% CI 0.22 to 2.41, I² 75%, 2 trials, 288 individuals) or other serious clinical outcomes. Adverse events and compliance were poorly reported.

Conclusions

Our results showed that insufficient evidence exists to suggest a beneficial effect of omega-3 PUFA supplementation in adults with peripheral arterial disease with regard to cardiovascular events and other serious clinical outcomes.

Omega-3 fatty acids for postoperative atrial fibrillation: alone or in combination with antioxidant vitamins?

BACKGROUND

The effects of omega-3 polyunsaturated fatty acids (PUFA) on the prevention of postoperative atrial fibrillation (POAF) are inconclusive in current studies. Moreover, the most appropriate composition of PUFA to play the protective role is unclear. The aim of this meta-analysis was to ascertain the protective role of PUFA on POAF and the most appropriate composition.

METHODS

Studies were identified through PubMed, CENTRAL, EMBASE, reviews and reference lists of relevant papers. The odds ratio (OR) was calculated for POAF. Statistical analyses were performed with Review Manager 5.0.

RESULTS

Eleven randomised controlled trials with 3137 patients were included in the analysis. The use of PUFA alone did not reduce the incidence of POAF compared with the control (OR: 0.76; 95% confidence interval [CI]: 0.57-1.03; P=0.08; I(2)=52%). However, combination therapy with PUFA and vitamins C and E reduced the incidence of POAF by 68% (OR: 0.32; 95%CI: 0.17-0.60; P=0.0005; I(2)=38%). Subgroup analysis indicated that the ratio of EPA/DHA 1:2 was effective in preventing POAF (OR: 0.35; 95%CI: 0.24-0.50; P<0.00001; I(2)=0%), while the ratio not 1:2 failed.

CONCLUSIONS

Combination therapy with PUFA and vitamins C and E is effective in the prevention of POAF while PUFA alone is not. The ratio of EPA/DHA may influence the incidence of POAF, and 1:2 may be most appropriate. Studies about PUFA on the prevention of POAF are still worthwhile to be conducted in the future.

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 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.