Changes in EPA and DHA during supplementation with omega-3 fatty acids and incident cardiovascular events: secondary analysis from the OMEMI trial

Background

In the OMEMI trial, elderly post-MI patients did not achieve reduction in cardiovascular events from supplementation of 1.8g n-3 polyunsaturated fatty acids (PUFA). In two recent trials of hypertriglyceridaemic patients the REDUCE-IT trial demonstrated an association between high levels of serum eicosapentaenoic acid (EPA) and reduced risk of CV events with 4 g/day icosapent ethyl supplements while in the STRENGTH trial no such association was present in patients treated with 4 g/day of EPA+ docosahexaenoic acid (DHA).

Purpose

To assess associations between changes in concentrations of EPA and DHA during two years supplementation with n-3 PUFA and incident cardiovascular events in the OMEMI trial.

Methods

In the randomized controlled OMEMI trial, 1014 elderly patients with a recent acute myocardial infarction (AMI) were treated with 1.8g/day of EPA and docosahexaenoic acid (DHA) or placebo for two years, and followed for the primary outcome of MACE (AMI, coronary revascularization, stroke or heart failure hospitalization) and secondary outcome of new-onset atrial fibrillation (AF). Serum concentrations of EPA and DHA were measured at inclusion and at study completion by gas chromatography, and reported as % weight of total FA (%wt) in serum phospholipids.

Results

Serial EPA and DHA measurements at study inclusion and completion were available in 881 patients (92% of survivors). At baseline EPA and DHA concentrations were (mean±SD) 2.84±1.41 and 5.71±1.35%wt, respectively. Higher baseline EPA and DHA concentrations were associated with previous n-3 PUFA supplementation, lower prevalence of current smoking and diabetes, lower levels of triglycerides and higher levels of HDL-cholesterol (all p<0.05). In patients randomized to n-3 PUFA, EPA and DHA increased with 2.32±1.92 and 0.91±1.19%wt, respectively, whereas in the placebo group EPA and DHA decreased with −0.39±1.37 and −0.43±1.13%wt, respectively. Greater increases in EPA and DHA during follow-up were associated with a lowering of triglyceride concentrations, increasing HDL concentrations, and lower baseline concentrations of EPA and DHA (all p<0.001). Among patients treated with n-3 PUFA (n=438), a greater increase in EPA was associated with a lower risk of incident MACE (HR 0.89 [95% CI 0.78–1.00] per %wt, p=0.059) and higher risk of new-onset AF in patients free of AF at inclusion (n=339): HR 1.31 [1.06–1.62] per %wt, p=0.012 (Figure). There were no such associations for changes in DHA: HR 0.86 (95% CI 0.70–1.05), p=0.13 for MACE and HR 1.29 (0.91–1.83), p=0.16 for new-onset AF.

Conclusion

Patients treated with 1.8 g/day n-3 PUFA for two years experienced a doubling of serum EPA concentrations. Greater increases in EPA were associated with a lower risk of MACE, but also a higher risk of new-onset AF. Changes in DHA concentrations were not associated with outcomes, suggesting that EPA may be the more important n-3 PUFA with respect to risk of cardiovascular events.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Oslo University Hospital, Ullevål Figure 1

Circulating trimethyllysine and risk of acute myocardial infarction in patients with suspected stable coronary heart disease

BACKGROUND

The carnitine precursor trimethyllysine (TML) is associated with progression of atherosclerosis, possibly through a relationship with trimethylamine-N-oxide (TMAO). Riboflavin is a cofactor in TMAO synthesis. We examined prospective relationships of circulating TML and TMAO with acute myocardial infarction (AMI) and potential effect modifications by riboflavin status.

METHODS

By Cox modelling, risk associations were examined amongst 4098 patients (71.8% men) with suspected stable angina pectoris. Subgroup analyses were performed according to median plasma riboflavin.

RESULTS

During a median follow-up of 4.9 years, 336 (8.2%) patients experienced an AMI. The age- and sex-adjusted hazard ratio (HR) (95% CI) comparing the 4th vs. 1st TML quartile was 2.19 (1.56-3.09). Multivariable adjustment for traditional cardiovascular risk factors and indices of renal function only slightly attenuated the risk estimates [HR (95% CI) 1.79 (1.23-2.59)], which were particularly strong amongst patients with riboflavin levels above the median (P_int  = 0.035). Plasma TML and TMAO were strongly correlated (r_s  = 0.41; P < 0.001); however, plasma TMAO was not associated with AMI risk in adjusted analyses [HR (95% CI) 0.81 (0.58-1.14)]. No interaction between TML and TMAO was observed.

CONCLUSION

Amongst patients with suspected stable angina pectoris, plasma TML, but not TMAO, independently predicted risk of AMI. Our results motivate further research on metabolic processes determining TML levels and their potential associations with cardiovascular disease. We did not adjust for multiple comparisons, and the subgroup analyses should be interpreted with caution.

Influence of a Concentrated Ethylester Compound of n-3 Fatty Acids on Lipids, Platelets and Coagulation in Patients Undergoing Coronary Bypass Surgery

Twenty patients accepted for coronary bypass surgery were randomized to receive either a concentrated ethylester compound of n-3 fatty acids, with a daily dose of 3.15 g of eicosapentaenoic acid (EPA) and 1.89 g of docosahexaenoic acid (DHA), or corn oil (controls) in a double blind study, to evaluate the effect on lipids, platelets and coagulation during the pre- and postoperative phase.

Only patients with fasting triglyceride (TG) levels ≥1.6 mmol/1 at recruitment were eligible. The study was continued for 5 to 6 months. Surgery was usually performed at mid-intervention. Blood samples were collected during morning hours in fasting subjects, just prior to intervention, preoperatively and at final postoperative follow-up. Moreover, blood loss was accurately accounted for postoperatively.

A threefold increase (p = 0.0001) of EPA was noted at pre-and postoperative follow-up. TG-levels were reduced 20 and 39%, respectively, in patients on n-3 fatty acids, reaching statistical significance at end of intervention (p = 0.034). TG-levels in controls remained largely unchanged. In patients on n-3 fatty acids, there was a statistically significant increase in serum total cholesterol preoperatively, but this change was no longer present at completion of the study.

No significant changes were noted in platelet function, as judged by bleeding time, collagen induced platelet aggregation and release of TxB2 during aggregation. Parameters of extrinsic coagulation, including phospholipase C-sensitive factor VII (PLC-VII) and extrinsic pathway inhibitor (EPI), also remained essentially unchanged in both groups of patients. However, fibrinogen was significantly reduced in controls (p <0.05) at end of intervention. Moreover, a strong positive correlation was noted between PLC-VII and TG (r = 0.77, p = 0.0001).

No significant difference in postoperative bleeding was noted between the two groups of patients.

Venous Thrombosis Following Diagnostic Transvenous Catheterization by Percutaneous Catheter Insertion: An Evaluation of Desmopressin as a Thromboprophylactic Agent

The preventive effect of desmopressin with respect to catheter induced thrombosis was studied in a randomized double-blind trial, consisting of 30 patients undergoing percutaneous transcubital right heart catheterization. Phlebography of the catheterized arm was performed after five days. The frequency of postcatheterization thrombosis was reduced by 33 per cent, from 86 per cent in the treatment group to 53 per cent in the control group (0.1 <p <0.2). This effect was restricted to minor thrombi, whereas major thrombosis could not be prevented.

Patient materials such as that of the present study, may become useful in preliminary investigations of thromboprophylactic agents.

Binding of Various Thrombin Fractions to Fibrin and the Influence of AT-III on Their Adsorption

Human thrombin with high affinity for fibrin was obtained by subjecting purified thrombin to affinity chromatography on Sepharose insolubilized fibrin monomers, after addition of a radioiodinated subsample of thrombin, molar ratio 1:600. As judged by radioprofiling of the electrophoretic distribution of high-affinity thrombin on 10 per cent polyacrylamide gel containing urea/SDS, the preparation consisted of 70 per cent a-thrombin, 28 per cent β-thrombin and only 2 per cent γ-thrombin. Although a-thrombin was bound more strongly to insolubilized fibrin monomers than the other subfractions, complete separation of the individual components could not be achieved.

High-affinity thrombin was employed for studies on thrombin adsorption to polymerized fibrin, assuming equal behaviour of labelled and unlabelled thrombin.

o avoid passive entrapment of thrombin within the fibrin meshwork at physiological pH, ionic strength and calcium concentration, the optimal fibrinogen concentration was found to be 2.94 umol/1. During such conditions, adsorption of thrombin to polymerized fibrin did not exceed 65 per cent of added thrombin, despite an increasing availability of fibrin-related thrombin binding domains obtained by reducing the thrombin concentration.

Adsorption of thrombin to polymerized fibrin increased by 25 per cent when the ionic strength was reduced to 0.05 mol/1. These findings suggest the presence of thrombin subfractions with different affinities for polymerized fibrin.

Aggregates of high-affinity thrombin formed during its preparation by affinity chromatography, but were prevented by adding polyethylene glycol (m.w. 6,000, final conc. 6.6 g/1). Such aggregates were not inactivated by AT-III, but could still adsorb to polymerized fibrin.

In its monomeric form fibrin-adsorbed thrombin was inactivated by AT-III and could then be extruded from the clot upon syneresis and retraction, but a small fraction remained attached to polymerized fibrin, exhibiting minor amidolytic activity.

Functional and Antigenic Antithrombin III Values in Plasma and Serum from 115 Regular Blood Donors and Antithrombin III In Prediction of Postoperative Thrombosis

Antithrombin III (AT-III) was determined functionally using chromogenic substrate (S-2238) and immunologically using radial immunodiffusion (RID) in plasma and serum from 115 blood donors. There was a decrease in functional activity by 43.5% and in antigen concentration by 18.4% during in vitro coagulation when corresponding serum and plasma samples were compared. A positive correlation was found between the two methods in plasma (r=0.784) as well as in serum (r = 0.658). RID in serum correlated well with RID in plasma (r = 0.811), but the correlation for S-2238 in plasma and serum was poor (r = 0.411). Functional AT-III decrease during coagulation was uncorrelated with age and fibrinogen, and was not statistically affected by sex, smoking or blood groups.

Preoperative functional AT-III activity was measured in 25 patients undergoing elective hip replacement, 60% of whom developed postoperative thrombosis. The functional activity in serum discriminated well between the thrombotic and nonthrombotic group of patients (p<0.025), whereas the activity in plasma showed only a minor difference.

A Clinical and Phlebographie Study of Postoperative Deep Vein Thrombosis Following Knee Meniscus Extirpation

To evaluate the risk of deep vein thrombosis, a clinical and phlebographic examination was performed 7 to 16 days after a bloodless knee meniscus operation in 37 male patients aged 20 to 35 years. Anticoagulant prophylaxis was not administered. Phlebography revealed asymptomatic calf vein thrombosis in three patients and these were not treated. In two of these phlebography was repeated after six weeks, and complete regression of the thrombi was noted.

The present study may underestimate the frequency of postoperative venous thrombosis, as some thrombi may already have lysed at the time of phlebography. However, our results indicate a low incidence of thrombosis after knee meniscus extirpation.

Lipopolysaccharide Induced Monocyte Thromboplastin Synthesis and Coagulation Responses in Patients Undergoing Coronary Bypass Surgery after Preoperative Supplementation with n-3 Fatty Acids

Twenty patients with coronary heart disease (CHD) and elevated serum lipids were randomized into 2 groups of 10 to receive encapsulated preparations of either a concentrated ethylester form of eicosapentaenoic acid (EPA) and docosa-hexaenoic acid (DHA) or corn oil in doses of 6 g per day, given double blindly for approximately two months prior to coronary bypass surgery. Lipopolysaccharide (LPS) induced monocyte thromboplastin synthesis was studied during the preoperative period and one week following surgery. The ability of n-3 fatty acids to modify tissue factor pathway inhibitor (TFPI) and tissue plasminogen activator inhibitor (PAI-1) was also evaluated along with fibrinogen and thrombin-antithrombin III (TAT) complexes.

No significant changes were noted preoperatively. Monocyte reactivity, PAI-1, fibrinogen and TAT increased significantly after surgery. These changes were not modified by preoperative loading with n-3 fatty acids.

Association of plasma neopterin with risk of an inpatient hospital diagnosis of atrial fibrillation: results from two prospective cohort studies

BACKGROUND

Link between inflammation and atrial fibrillation (AF) has been increasingly recognized. Neopterin, a biomarker of cellular immune activation, may be associated with incident AF.

OBJECTIVE

To investigate the association between plasma neopterin levels and risk of an inpatient hospital diagnosis of AF, and to evaluate a joint association of neopterin and a nonspecific inflammatory marker C-reactive protein (CRP) in two prospective cohorts.

METHODS

We performed a prospective analysis from a community-based cohort (the Hordaland Health Study (HUSK), n = 6891), and validated the findings in a cohort of patients with suspected stable angina pectoris (the Western Norway Coronary Angiography Cohort (WECAC), n = 2022).

RESULTS

In both cohorts, higher plasma levels of neopterin were associated with an increased risk of incident AF after adjustment for age, sex, body mass index, current smoking, diabetes, hypertension and renal function. The multivariable-adjusted hazard ratio (HR) (95% CI) per one SD increment of log-transformed neopterin was 1.20 (1.10-1.32) in HUSK and 1.26 (1.09-1.44) in WECAC. Additional adjustment for CRP did not materially affect the risk association for neopterin. The highest risk of AF was found among individuals with both neopterin and CRP levels above the median (HR: 1.54; 95% CI: 1.16-2.05 in HUSK and HR: 1.67; 95% CI: 1.11-2.52 in WECAC).

CONCLUSIONS

Our findings indicate an association of plasma neopterin with risk of an inpatient hospital diagnosis of AF, which remains after adjustment for traditional risk factors as well as for CRP. This study highlights a role of cellular immune activation, in addition to inflammation, in AF pathogenesis.

Atherothrombogenic Risk Modulation by n-3 Fatty Acids Was not Associated with Changes in Homocysteine in Subjects with Combined Hyperlipidaemia

Favourable effects of n-3 fatty acids on the atherogenic risk profile were recently demonstrated in subjects with combined (type IIb) hyperlipidaemia, not responding to a therapeutic diet.

Re-examination of a previous patient material was performed to assess the influence of n-3 fatty acids on homocysteine and several coagulation factors.

Subjects were randomly allocated to receive either a concentrated compound of 85% eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) (n = 28), or corn oil (n = 29), in a daily dose of 4 g for 12 weeks. The intervention was double-blind.

Homocysteine remained unchanged in both groups after 12-week treatment. N-3 fatty acids supplementation did not affect the levels of fibrinogen, coagulation factor VII or tissue factor pathway inhibitor (TFPI), while plasminogen activator inhibitor (PAI) increased significantly (Student’s t-test; p <0.05). Total blood platelets were significantly reduced in subjects receiving n-3 fatty acids (Student’s t-test; p <0.05), whereas bleeding times increased non-significantly.

Activated factor XII type A predicts long-term mortality in patients admitted with chest pain

BACKGROUND

We assessed the relation between admission levels of activated factor XII type A (XIIaA), and long-term all-cause and cardiac mortality and recurrent troponin T (TnT) positive cardiovascular events in a consecutive cohort of 870 patients admitted with a clinically strongly suspected acute coronary syndrome (ACS).

METHODS AND RESULTS

After a 24-month follow-up period, 138 patients (15.8%) had died and 155 (17.8%) had suffered from a recurrent TnT positive (TnT > 0.05 ng mL(-1)) event. XIIaA levels were significantly lower in long-term survivors than in patients who died (22.9 (17.7-32.1) vs. 27.2 (20.0-39.7) pmol L(-1) [median, 25 and 75% percentiles], P < 0.001). The unadjusted hazard ratio for death within 2 years in patients with XIIaA in the highest quartile was 2.49 (95% confidence interval (CI), 1.52-4.06) as compared with patients with XIIaA in the lowest quartile. In a stepwise Cox regression model for death within 2 years, XIIaA added prognostic information for all-cause mortality (HR 2.05; 95% CI, 1.21-3.47) above and beyond age, a history of heart failure, ST-segment elevation, TnT and B-type natriuretic peptide (BNP). In the subgroup of patients with an admission TnT < or = 0.05 ng mL(-1), XIIaA provided independent prognostic information for all-cause mortality (HR 3.88; 95% CI, 1.66-9.08) and for the combined endpoint of death or recurrent TnT positive event (HR 2.46; 95% CI, 1.34-4.50).

CONCLUSION

XIIaA, a recently identified in vivo form of activated factor XII is an independent indicator of long-term all-cause mortality in patients admitted with chest pain, providing prognostic information above and beyond conventional risk factors.

Homocysteine-lowering therapy does not affect inflammatory markers of atherosclerosis in patients with stable coronary artery disease

OBJECTIVES

A high level of total homocysteine (tHcy) is a risk marker for cardiovascular disease (CVD), and is related to inflammation. We wanted to test the effect of homocysteine-lowering B-vitamin therapy, as used in the Western Norway B-vitamin Intervention Trial (WENBIT), on inflammatory markers associated with atherosclerosis.

DESIGN

Single centre, prospective double-blind clinical interventional study, randomised in a 2 x 2 factorial design.

SUBJECTS AND METHODS

Ninety patients (21 female) with suspected coronary artery disease (CAD), aged 38-80 years, were blindly randomised into one of four groups of daily oral treatment with (A) folic acid (0.8 mg)/vitamin B12 (0.4 mg)/vitamin B6 (40 mg), (B) folic acid/vitamin B12, (C) vitamin B6 alone or (D) placebo. Blood samples were collected before and after 6 months of treatment.

RESULTS

Before intervention, median levels of the analytes were: tHcy 11.0 micromol L(-1), neopterin 8.1 nmol L(-1), soluble CD40 ligand (sCD40L) 3.9 ng mL(-1), interleukin (IL)-6 1.9 pg mL(-1), C-reactive protein (CRP) 1.9 mg L(-1) and low-density lipoprotein (LDL) cholesterol 3.3 mmol L(-1). tHcy was significantly associated with neopterin (r = 0.49, P < 0.001) and with IL-6 (r = 0.29, P = 0.01), but not with CRP or sCD40L. Neither treatment with folic acid/B12 nor with B6 induced significant changes in any of these inflammatory biomarkers (P >or= 0.14). In patients receiving folic acid/B12 (groups A and B), tHcy was reduced with 33% (P < 0.001).

CONCLUSIONS

In patients with stable CAD, homocysteine-lowering therapy with B-vitamins does not affect levels of inflammatory markers associated with atherogenesis. Failure to reverse inflammatory processes, may partly explain the negative results in clinical secondary B-vitamin intervention trials.

Holotranscobalamin and methylmalonic acid as prognostic markers following an acute myocardial infarction

OBJECTIVE

To evaluate whether low levels of holotranscobalamin (holoTC) or elevated levels of methylmalonic acid (MMA), both indicators of vitamin B(12) deficiency, might predispose to new cardiovascular events following an acute myocardial infarction (MI).

DESIGN

A prospective prognostic study.

SETTING

One hospital center in Stavanger, Norway.

SUBJECTS

A total of 300 patients admitted with an acute MI.

METHODS

Registration of new TnT positive coronary events (defined as TnT>0.05 microg/l and a typical MI pattern) and/or cardiac death during a median follow-up time of 45 months.

RESULTS

We compared the recurrence of events in the lowest quartile of holoTC (Q1<73.9 pmol/l) to the event rate above the 25% percentile (Q2-4). For methylmalonic acid (MMA) the same comparison was carried out for the upper quartile (Q4 > or =0.24 micromol/l) as compared with the event rate below the 75% percentile (Q1-3). After 18 and 45 months of follow-up, the odds ratio (OR) for Q1 vs Q2-4 for holoTC was 1.15 (95% confidence interval (CI) 0.91-1.46, P=0.25) and 1.05 (95% CI 0.86-1.29, P=0.64), respectively. For MMA the OR for Q4 vs Q1-3 was 0.95 (95% CI 0.76-1.19, P=0.67) after 18 months and 1.01 (95% CI 0.83-1.23, P=0.90) after 45 months.

CONCLUSION

This study showed no increased risk of future cardiovascular events associated with low levels of holoTC or high levels of MMA following an acute MI.

Increased lipid peroxidation during long-term intervention with high doses of n-3 fatty acids (PUFAs) following an acute myocardial infarction

OBJECTIVE

To assess the oxidative burden of a highly concentrated compound of n-3 PUFAs as compared to corn oil by measuring thiobarbituric acid-malondialdehyde complex (TBA-MDA) by HPLC. We also studied the influence on TBA-MDA of statins combined with n-3 PUFAs or corn oil.

DESIGN

A prospective, randomised, double-blind, controlled study.

SETTING

One hospital centre in Stavanger, Norway.

SUBJECTS

A total of 300 subjects with an acute myocardial infarction (MI).

INTERVENTIONS

Gelatine capsules, containing 850-882 mg EPA and DHA as concentrated ethylesters, or 1 g of corn oil, were ingested in a dose of two capsules twice a day for at least 1 y. Alpha-tocopherol (4 mg) was added to all capsules to protect the PUFAs against oxidation.

RESULTS

After 1 y TBA-MDA increased modestly in the n-3 PUFA group (n=125), as compared to the corn oil group (n=130), P=0.027. Multiple linear regression analyses of fatty acids in serum total phospholipids (n=56) on TBA-MDA measured after 12 months intervention, showed no dependency. Performing best subsets regression, serum phospholipid concentration of arachidonic acid (20:4 n-6 PUFA) was identified as a predictor of TBA-MDA at 12 months follow-up, P=0.004. We found no impact of statins on TBA-MDA.

CONCLUSION

TBA-MDA increased modestly after long-term intervention with n-3 PUFAs compared to corn oil post-MI, suggesting biological changes induced by n-3 PUFAs, rather than simply reflecting their concentration differences. The peroxidative potential of n-3 PUFAs was not modified by statin treatment.

SPONSORSHIP

: Pharmacia A/S and Pronova A/S, Norway.

Characteristics and prognostic impact of plasma fibrin monomer (soluble fibrin) in patients with coronary artery disease

We measured fibrin monomer (FM), soluble fibrin, as a marker of thrombin activity in plasma samples obtained in parallel with the first two routine samples for cardiac markers in 165 patients with acute chest pain admitted consecutively to our hospital. A reference limit of FM in a healthy population was set at 3.0 mg/l. Elevated plasma FM was observed in 48.8% of patients with acute coronary syndromes, in 42.3% of patients with specific non-coronary disease, in 31.5% of those with stable angina pectoris and in 18.2% of patients with non-specific chest pain. No significant difference was observed between sample 1 and sample 2 in patients not receiving thrombolytic treatment during the sampling period (P = 0.46). In patients with coronary artery disease, FM was significantly related to the level of cardiac troponin T (P = 0.001), but no correlation was observed between the individual plasma FM and cardiac troponin T values. Outcome analysis during the following 30 months after the index event in patients with acute coronary syndromes revealed higher FM levels in those with coronary re-events or death than in patients without new events (P = 0.001). This observation indicates a prognostic potential of FM in risk evaluation of patients with coronary artery disease.