Eicosapentaenoic acid for the prevention of recurrent atrial fibrillation

Omega-3 Index and Anti-Arrhythmic Potential of Omega-3 PUFAs

Omega-3 polyunsaturated fatty acids (PUFAs), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are permanent subjects of interest in relation to the protection of cardiovascular health and the prevention of the incidence of both ventricular and atrial arrhythmias. The purpose of this updated review is to focus on the novel cellular and molecular effects of omega-3 PUFAs, in the context of the mechanisms and factors involved in the development of cardiac arrhythmias; to provide results of the most recent studies on the omega-3 PUFA anti-arrhythmic efficacy and to discuss the lack of the benefit in relation to omega-3 PUFA status. The evidence is in the favor of omega-3 PUFA acute and long-term treatment, perhaps with mitochondria-targeted antioxidants. However, for a more objective evaluation of the anti-arrhythmic potential of omega-3 PUFAs in clinical trials, it is necessary to monitor the basal pre-interventional omega-3 status of individuals, i.e., red blood cell content, omega-3 index and free plasma levels. In the view of evidence-based medicine, it seems to be crucial to aim to establish new approaches in the prevention of cardiac arrhythmias and associated morbidity and mortality that comes with these conditions.

Omega 3 and atrial fibrillation: Where are we?

Anti-arrhythmic properties of n-3 polyunsaturated fatty acids, at least in part mediated by anti-oxidant, anti-inflammatory and anti-fibrotic power, have been widely proved. Effect of fish oil on atrial fibrillation, both in primary and in secondary prevention and after cardiac surgery, are controversial, mostly due to lack of homogeneity between studies but also due to individual variability in response to fatty acids administration. Inclusion of measurement of incorporation of fish oil into cell membranes, appears to be essential in future studies, to assess their antiarrhythmic effect.

Icosapent Ethyl (Eicosapentaenoic Acid Ethyl Ester): Effects Upon High-Sensitivity C-Reactive Protein and Lipid Parameters in Patients With Metabolic Syndrome

BACKGROUND

The aim of this analysis was to examine the effects of icosapent ethyl (eicosapentaenoic acid ethyl ester, IPE) on high-sensitivity C-reactive protein (hsCRP) and lipid parameters in patients with metabolic syndrome, with and without stable statin therapy.

METHODS

This post hoc exploratory analysis evaluated patients with metabolic syndrome treated with IPE 4 grams/day, IPE 2 grams/day, or placebo in phase 3, randomized, placebo-controlled studies entitled: MARINE [triglyceride (TG) levels ≥500 and ≤2000 mg/dL] and ANCHOR [TG levels ≥200 and <500 mg/dL, despite low-density lipoprotein cholesterol (LDL-C) control with stable statin therapy].

RESULTS

Compared with placebo in patients with metabolic syndrome in MARINE (n=204) and ANCHOR (n=645), at the approved dose of 4 grams/day, IPE significantly lowered hsCRP levels 40.0% (P=0.0007) in MARINE and 23.0% (P=0.0003) in ANCHOR. Compared with placebo in MARINE, which included patients with and without statin therapy, IPE 4 grams/day significantly reduced hsCRP levels 78.0% in statin-treated patients (P=0.0035, n=16). Compared with placebo in MARINE, IPE 4 grams/day significantly reduced TG levels (35.0%; P<0.0001), non-high-density lipoprotein cholesterol (non-HDL-C; 19.9%; P<0.0001), and apolipoprotein B levels (ApoB) (9.1%; P=0.0015) without raising LDL-C levels. Compared with placebo in ANCHOR, IPE 4 grams/day significantly reduced TG (21.7%; P<0.0001), non-HDL-C (13.5%; P<0.0001), ApoB (8.8%; P<0.0001), LDL-C (5.2%; P=0.0236), and HDL-C levels (4.0%; P=0.0053).

CONCLUSIONS

Compared with placebo, IPE 4 grams/day significantly lowered hsCRP levels and improved lipids without raising LDL-C levels in patients with metabolic syndrome and high (≥200 and <500 mg/dL) or very high (≥500 and ≤2000 mg/dL) TG levels, with or without stable statin therapy.

Effect of omega-three polyunsaturated fatty acids on inflammation, oxidative stress, and recurrence of atrial fibrillation

The efficacy of omega-3 polyunsaturated fatty acids (n-3 PUFAs) in preventing recurrence of atrial fibrillation (AF) is controversial and their effects on inflammation and oxidative stress in this population are not known. This study examined the effects of high-dose marine n-3 PUFAs added to conventional therapy on the recurrence of AF and on markers of inflammation and oxidative stress. Patients with paroxysmal or persistent AF were randomized to n-3 PUFAs (4 g/day; n = 126) or placebo (n = 64) in a 2:1 ratio in a prospective, double-blind, placebo-controlled, parallel group study. The primary outcome was time to recurrence of AF. Secondary outcomes were changes in biomarkers of inflammation (serum interleukin [IL]-6, IL-8, IL-10, tissue necrosis factor alpha, monocyte chemoattractant protein-1, and vascular endothelial growth factor), N-terminal-pro-brain-type natriuretic peptide, and oxidative stress (urinary F2-isoprostanes). AF recurred in 74 patients (58.7%) randomized to n-3 PUFAs and in 30 patients (46.9%) who received placebo; time to recurrence of AF did not differ significantly in the 2 groups (hazard ratio 1.20; 95% confidence interval 0.76 to 1.90, adjusted p = 0.438). Compared with placebo, n-3 PUFAs did not result in clinically meaningful changes in concentrations of inflammatory markers, N-terminal-pro-brain-type natriuretic peptide or F2-isoprostanes. In conclusion, in patients with paroxysmal or persistent AF, treatment with n-3 PUFAs 4 g/day did not reduce the recurrence of AF, nor was it associated with clinically important effects on concentrations of markers of inflammation and oxidative stress. (Clinical trial registration number, NCT 00552084.).

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.

Icosapent ethyl, a pure ethyl ester of eicosapentaenoic acid: effects on circulating markers of inflammation from the MARINE and ANCHOR studies

BACKGROUND

Icosapent ethyl (IPE) is a high-purity prescription form of eicosapentaenoic acid ethyl ester approved by the US Food and Drug Administration as an adjunct to diet to reduce triglyceride (TG) levels in adult patients with severe (≥500 mg/dL) hypertriglyceridemia. In addition to TG-lowering effects, IPE also reduces non-high-density lipoprotein cholesterol and apolipoprotein B levels without significantly increasing low-density lipoprotein cholesterol (LDL-C) in patients with very high TG levels ≥500 mg/dL (MARINE study) and in patients with well-controlled LDL-C and residually high TG levels 200-500 mg/dL (ANCHOR study). This analysis examined the effect of IPE on inflammatory markers in patients from MARINE and ANCHOR.

METHODS

MARINE (N = 229) and ANCHOR (N = 702) were Phase III, double-blind studies that randomized hypertriglyceridemic patients to IPE 4 g/day, 2 g/day, or placebo. This analysis assessed the median placebo-adjusted percentage change from baseline in markers representing various stages of atherosclerotic inflammation such as intercellular adhesion molecule-1 (ICAM-1), oxidized low-density lipoprotein (Ox-LDL), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP).

RESULTS

Compared to placebo, IPE 4 g/day significantly decreased Ox-LDL (13 %, p < 0.0001, ANCHOR), Lp-PLA(2) (14 %, p < 0.001, MARINE; 19 %, p < 0.0001, ANCHOR), and hsCRP levels (36 %, p < 0.01, MARINE; 22 %, p < 0.001, ANCHOR), but did not significantly change ICAM-1 and IL-6 levels. In the MARINE study, IPE 2 g/day did not significantly change ICAM-1, Ox-LDL, Lp-PLA(2), IL-6, or hsCRP levels. Also, compared to placebo in the ANCHOR study, IPE 2 g/day significantly decreased Lp-PLA(2) levels (8 %, p < 0.0001), but did not significantly change levels of other assessed inflammatory markers.

CONCLUSION

Compared to placebo, in hypertriglyceridemic patients, IPE 4 g/day significantly decreased Ox-LDL, Lp-PLA(2), and hsCRP levels.

Omega-3 Polyunsaturated Fatty Acid Supplementation: Mechanism and Current Evidence in Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent arrhythmia and is associated with considerable morbidity and mortality. Available pharmacologic antiarrhythmic therapies are often ineffective in preventing the recurrence of AF, possibly because these drugs target a single pathophysiological mechanism. Given their beneficial effects on ventricular arrhythmias, omega-3 polyunsaturated fatty acids (n-3 PUFAs) have recently been investigated as possible candidates in the treatment of supraventricular arrhythmias. In this review, we explore the current understanding of the antiarrhythmic effects attributed to n-3 PUFAs including direct modulation of ionic channels, improvement of membrane fluidity, anti-inflammatory and antifibrotic effects, and modulation of sympatho-vagal balance. We will then focus on the results of epidemiologic studies exploring the associations between nutritional intake of n3 PUFAs and the incidence of AF, and will review the findings of the clinical trials investigating the effects of n-3 PUFAs supplementation in the prophylaxis of AF and in the prevention of its recurrences.

Omega-3 Fatty acids: anti-arrhythmic, pro-arrhythmic, or both?

This review focuses on developments after 2008, when the topic was last reviewed by the author. Pertinent publications were found by medline searches and in the author’s personal data base. Prevention of atrial fibrillation (AF) was investigated in a number of trials, sparked by one positive report on the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), considerations of upstream therapy, data from electrophysiologic laboratories and animal experiments. If EPA + DHA prevent postoperative AF, the effect is probably smaller than initially expected. The same is probably true for maintenance of sinus rhythm after cardioversion and for new-onset AF. Larger trials are currently ongoing. Prevention of ventricular arrhythmias was studied in carriers of an implanted cardioverter-defibrillator, with no clear results. This might have been due to a broad definition of the primary endpoint, including any ventricular arrhythmia and any action of the device. Epidemiologic studies support the contention that high levels of EPA + DHA prevent sudden cardiac death (SCD). However, since SCD is a rare occurrence, it is difficult to conduct an adequately powered trial. In patients with congestive heart failure, EPA + DHA reduced total mortality and rehospitalizations, but not SCD or presumed arrhythmic death. Of three trials in patients after a myocardial infarction, two were inadequately powered, and in one, the dose might have been too low. Taken together, while epidemiologic studies support an inverse relation between EPA + DHA and occurrence of SCD or arrhythmic death, demonstrating this effect in intervention trials remained elusive so far. A pro-arrhythmic effect of EPA + DHA has not been seen in intervention studies, and results of epidemiologic and animal studies also rather argue against such an effect. A different, and probably more productive, perspective is provided by a standardized analytical assessment of a person’s status in EPA + DHA by use of the omega-3 index, EPA + DHA in red cell fatty acids. In populations with a high omega-3 index, SCD is rare. Intervention trials can become more effective by including a low omega-3 index into the inclusion criteria, thus creating a study population more likely to demonstrate an effect of EPA + DHA. This is especially relevant in case of rare endpoints, like new-onset AF or SCD.