Predictors of myocardial lesions in men with minimal coronary atherosclerosis at autopsy. The Honolulu heart program

Temporal association of elevated C-reactive protein and periodontal disease in men

BACKGROUND

Most studies on the relationship between serum C-reactive protein (CRP) and periodontal disease have been cross-sectional. In this study, we investigated the temporal association between CRP and periodontal disease by following a large number of subjects for 1 year.

METHODS

We studied 11,162 men in Nagoya, Japan, who had an initial dental examination as part of a complete physical examination and then underwent the same examination 1 year later. For the 4,997 men without periodontal disease at baseline, logistic regression analysis was performed to examine the relationship between baseline CRP and periodontal disease 1 year later, adjusting for age, body mass index, glycosylated hemoglobin A1c level, and smoking status. Similarly, logistic regression analysis was performed to examine the relationship between periodontal disease at baseline and CRP 1 year later for the 10,376 men with normal baseline CRP, adjusting for the same confounding factors.

RESULTS

Among men without high CRP at baseline, periodontal disease at baseline correlated to CRP 1 year later. The odds ratio was 1.336 (95% confidence interval [CI]: 1.115 to 1.674). However, in the men without periodontal disease, no significant correlations were seen with baseline CRP or periodontal disease 1 year later. The odds ratio was 1.163 (95% CI: 0.894 to 1.513).

CONCLUSION

Periodontal disease increased the risk for high serum CRP levels in men after 1 year of follow-up.

Intakes of long-chain omega-3 fatty acid associated with reduced risk for death from coronary heart disease in healthy adults

Numerous organizations and national health agencies have begun to recommend consumption of the long-chain omega-3 fatty acids (FAs) eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA), respectively, in pill or fish form for general cardiovascular health. The purpose of this article is to present a rationale for an official target intake of 400 to 500 mg/d of EPA + DHA in the United States. Six epidemiologic studies reporting EPA + DHA intake and risk of coronary heart disease (CHD) death have been conducted in the United States, and five studies reported statistically significant inverse trends. Meta-analysis of these data showed a significant dose-response relationship between risk for CHD death and intake (P = 0.03), with relative risk reductions of 37% at an average EPA + DHA intake of 566 mg/d. Coincidentally, two servings per week of oily fish (the current American Heart Association recommendation) would provide 400 to 500 mg/d. We conclude, therefore, that an intake of 400 to 500 mg/d of EPA + DHA is achievable by diet alone and would be expected to significantly reduce risk for death from CHD in healthy adults.

The omega-3 index as a risk factor for coronary heart disease

Because blood concentrations of n-3 (or omega-3) fatty acids (FAs) (eicosapentaenoic and docosahexaenoic acids) are a strong reflection of dietary intake, it is proposed that a n-3 FA biomarker, the omega-3 index (erythrocyte eicosapentaenoic acid plus docosahexaenoic acid), be considered as a potential risk factor for coronary heart disease mortality, especially sudden cardiac death. The omega-3 index fulfills many of the requirements for a risk factor including consistent epidemiologic evidence, a plausible mechanism of action, a reproducible assay, independence from classic risk factors, modifiability, and, most important, the demonstration that raising levels will reduce risk for cardiac events. Measuring membrane concentrations of n-3 FAs is a rational approach to biostatus assessment as these FAs appear to exert their beneficial metabolic effects because of their actions in membranes. They alter membrane physical characteristics and the activity of membrane-bound proteins, and, once released by intracellular phospholipases from membrane stores, they can interact with ion channels, be converted into a wide variety of bioactive eicosanoids, and serve as ligands for several nuclear transcription factors, thereby altering gene expression. The omega-3 index compares very favorably with other risk factors for sudden cardiac death. Proposed omega-3 index risk zones are (in percentages of erythrocyte FAs): high risk, <4%; intermediate risk, 4-8%; and low risk, >8%. Before assessment of n-3 FA biostatus can be used in routine clinical evaluation of patients, standardized laboratory methods and quality control materials must become available.

Omega-3 fatty acids and cardiovascular disease: a case for omega-3 index as a new risk factor

The omega-3 fatty acids (FAs) found in fish and fish oils (eicosapentaenoic and docosahexaenoic acids, EPA and DHA) have been reported to have a variety of beneficial effects in cardiovascular diseases. Ecological and prospective cohort studies as well as randomized, controlled trials have supported the view that the effects of these FAs are clinically relevant. They operate via several mechanisms, all beginning with the incorporation of EPA and DHA into cell membranes. From here, these omega-3 FA alter membrane physical characteristics and the activity of membrane-bound proteins, and once released by intracellular phospholipases, can interact with ion channels, be converted into a wide variety of bioactive eicosanoids, and serve as ligands for several nuclear transcription factors thereby altering gene expression. In as much as blood levels are a strong reflection of dietary intake, it is proposed that an omega-3 FA biomarker, the omega-3 index (erythrocyte EPA+DHA) be considered at least a marker, if not a risk factor, for coronary heart disease, especially sudden cardiac death. The omega-3 index fulfils many of the requirements for a risk factor including consistent epidemiological evidence, a plausible mechanism of action, a reproducible assay, independence from classical risk factors, modifiability, and most importantly, the demonstration that raising tissue levels will reduce risk for cardiac events. For these and a number of other reasons, the omega-3 index compares very favourably with other risk factors for sudden cardiac death.

Effects of n-3 polyunsaturated fatty acid on upper limit of vulnerability shocks

BACKGROUND

Ventricular fibrillation (VF) can be induced when a strong shock is delivered during the vulnerable period of a cardiac cycle. VF, however, cannot be induced if the shock strength is increased to the "upper limit of vulnerability" (ULV) level. Docosahexaenoic acid (DHA) has been shown to prevent the occurrence of VF after coronary occlusion. However, its effects on the ULV have not been verified. We tested the hypothesis that ULV shock strength is decreased after DHA administration.

METHODS

In 10 pigs, 10 S1s (square, 5-ms) were delivered from the RV apex electrode at 300 ms cycle length. Shocks (S2, biphasic) were delivered from the RV-SVC electrodes after the last S1. The ULV was determined using an up/down protocol. In group 1 (n = 5), after the control ULV was determined at the beginning of the study, a solution containing 1.0 gm of DHA was infused intravenously within 90 min. The ULV (DHA-ULV) was determined again after the end of infusion. In group 2 (n = 5), the vehicle for DHA was infused instead of DHA to confirm that the vehicle did not have an effect on the ULV.

RESULTS

DHA-ULV (412 +/- 58 V, 12 +/- 3 J) was significantly decreased (P < 0.04) compared to the control ULV (478 +/- 32 V, 16 +/- 3 J). The ULV before (483 +/- 28 V, 16 +/- 1 J) and after (463 +/- 28 V, 15 +/- 2 J) the vehicle infusion was not different (P = 0.4). There was no change in the systolic blood pressure as well as heart rate in both groups.

CONCLUSION

DHA significantly decreases the ULV (13% by voltage and 25% by energy), suggesting that DHA can help to prevent VF induced by a strong stimulus delivered during the vulnerable period.

Reduced effect on apoptosis of 4-hydroxyhexenal and oxidized LDL enriched with n-3 fatty acids from postmenopausal women

BACKGROUND

Oxidized low-density lipoprotein (oxLDL) promotes apoptosis in atherosclerotic plaques in the vascular wall, a process mediated through its oxidized lipids. 4-Hydroxynonenal (HNE) and 4-hydroxyhexenal (HHE), derived from oxidation of n-6 and n-3 fatty acids, respectively, are among the major oxidized products in oxLDL.

HYPOTHESIS

This study hypothesized that eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA)-rich versus linoleic acid-rich oxLDL obtained from postmenopausal women and HNE versus HHE differentially influence apoptosis in U937 cells.

EXPERIMENTAL DESIGN

Thirty healthy postmenopausal women were supplemented with 14 g/day safflower oil (SO), 7 g/day of both fish oil and SO (low dose LFO) or 14 g/day fish oil (high dose HFO) for 5 weeks. Low-density lipoprotein, obtained after supplementation, was oxidized with 5 microM CuSO(4) at 37 degrees C for 6 h. The concentration of cholesteryl ester hydroperoxides (CEOOH) and conjugated dienes was measured in the oxidized LDL (oxLDL). U937 cells were incubated with the oxLDL, 10 microM of HHE, 7 muM of HHE plus 3 microM of HNE, 5 microM of both HHE and HNE or 10 microM of HNE and the extent of apoptosis measured three ways.

RESULTS

The concentration of CEOOH and conjugated dienes in oxLDL did not differ among the three treatment groups. The percent of apoptotic cells was approximately 40% lower when incubated with oxLDL obtained from the HFO-supplemented group than the SO-supplemented group measured by both the Annexin V and the DNA fragmentation assays (P = .04 and .004, respectively). Apoptosis of U937 cells was significantly lower in cells incubated with 10 microM of HHE, and mixtures of HHE and HNE than the 10 microM HNE when measured by the Annexin V, DNA fragmentation and 4,6-diamidino-2-phenylindole (DAPI) staining.

CONCLUSIONS

These data suggest that the cardioprotective properties of n-3 fatty acids may derive in part from their less reactive oxidized lipid metabolites.

Are omega-3 fatty acids the most important nutritional modulators of coronary heart disease risk?

With each passing year, the evidence linking an increased risk for coronary heart disease (CHD) death with a chronic dietary deficiency in long-chain omega-3 (n-3) fatty acids (FAs) grows stronger. Recently, a federally mandated evidence-based review in the United States concluded that n-3 FAs, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have clear cardioprotective effects, and national and international expert panels and health organizations have begun to call for increased EPA and DHA intakes. Consumption of between 450 and 1000 mg/d is recommended for those without and with known CHD, respectively. Based on animal and isolated cell studies, these FAs were presumed to have antiarrhythmic effects. The first direct evidence for this in humans was recently published, as were new data linking low n-3 FA intakes with risk for developing atrial fibrillation. The strength of the n-3 story has now led to a proposal that blood levels of EPA plus DHA be considered a new, modifiable, and clinically relevant risk factor for death from CHD.

Fish intake is associated with a reduced progression of coronary artery atherosclerosis in postmenopausal women with coronary artery disease

BACKGROUND

Higher intakes of fish and n-3 fatty acids are associated with a reduced risk of cardiovascular events and mortality. However, limited data exist on the effect of fish intake on actual measures of progression of coronary artery atherosclerosis.

OBJECTIVE

The aim was to examine the association between fish intake and the progression of coronary artery atherosclerosis in women with coronary artery disease.

DESIGN

This was a prospective cohort study of postmenopausal women (n = 229) participating in the Estrogen Replacement and Atherosclerosis trial. Usual fish intake was estimated at baseline with a food-frequency questionnaire. Quantitative coronary angiography was performed at baseline and after 3.2 +/- 0.6 (x +/- SD) y to evaluate changes in the mean minimum coronary artery diameter, the mean percentage of stenosis, and the development of new coronary lesions.

RESULTS

Compared with lower fish intakes, consumption of > or =2 servings of fish or > or =1 serving of tuna or dark fish per week was associated with smaller increases in the percentage of stenosis (4.54 +/- 1.37% compared with -0.06 +/- 1.59% and 5.12 +/- 1.48% compared with 0.35 +/- 1.47%, respectively; P < 0.05 for both) in diabetic women after adjustments for age, cardiovascular disease risk factors, and dietary intakes of fatty acids, cholesterol, fiber, and alcohol. These associations were not significant in nondiabetic women. Higher fish consumption was also associated with smaller decreases in minimum coronary artery diameter and fewer new lesions.

CONCLUSIONS

Consumption of fish is associated with a significantly reduced progression of coronary artery atherosclerosis in women with coronary artery disease.

The Omega-3 Index: a new risk factor for death from coronary heart disease?

BACKGROUND

Low intakes or blood levels of eicosapentaenoic and docosahexaenoic acids (EPA + DHA) are independently associated with increased risk of death from coronary heart disease (CHD). In randomized secondary prevention trials, fish or fish oil have been demonstrated to reduce total and CHD mortality at intakes of about 1 g/day. Red blood cell (RBC) fatty acid (FA) composition reflects long-term intake of EPA + DHA. We propose that the RBC EPA + DHA (hereafter called the Omega-3 Index) be considered a new risk factor for death from CHD.

METHODS

We conducted clinical and laboratory experiments to generate data necessary for the validation of the Omega-3 Index as a CHD risk predictor. The relationship between this putative marker and risk for CHD death, especially sudden cardiac death (SCD), was then evaluated in several published primary and secondary prevention studies.

RESULTS

The Omega-3 Index was inversely associated with risk for CHD mortality. An Omega-3 Index of > or = 8% was associated with the greatest cardioprotection, whereas an index of < or = 4% was associated with the least.

CONCLUSION

The Omega-3 Index may represent a novel, physiologically relevant, easily modified, independent, and graded risk factor for death from CHD that could have significant clinical utility.

Absence of cardiovascular benefits and sportfish consumption among St. Lawrence River anglers

The benefits of sportfish consumption and omega-3 fatty acid (omega3-FA) intake for cardiovascular risk factors were evaluated in a sample of 112 male fishers from the St. Lawrence River in the Montreal area during the 1996 winter and fall fishing seasons. A questionnaire on fishing practices and fish consumption was administered, and fasting blood samples were collected for lipid and phospholipid determination. Linear regression analyses, which considered the confounding effect of major risk factors, did not show any significant association between measured omega3-FAs or reported fish intake and blood lipids or blood pressure. This study is limited by its low statistical power due to the small sample size and the possibility that the fish eaten by the participants were low in omega3-FAs or that the participants diets contained foods high in cholesterol-raising fat.

Fish oil inhibits photochemically induced thrombosis in the guinea pig in a dose dependent manner

The dose-response effect of dietary fish oil was investigated in the photochemically induced thrombosis model in guinea pigs. In this arterial thrombosis model thrombus formation was evaluated by determination of different occlusion parameters (percentage of occlusion, area under the blood flow curve, time to first occlusion, spontaneous reflow). Sixty guinea pigs (7 weeks old) were randomly assigned to and fed a 40 energy % diet containing increasing amounts (0, 5.5, 17 and 36 energy %) of fish oil for four weeks. Arterial thrombosis was induced in the femoral artery by free radical damage and subsequent thrombus formation. Increasing fish oil concentrations in the diet were associated with a linear decrease (p<0.001) in the percentage of occlusion (calculated as a decrease in blood flow) and a linear increase in area under the blood flow curve/begin flow (p<0.001). The time to thrombus formation was not significantly prolonged in any group. However the frequency of animals in which complete occlusion of the femoral artery was not obtained during the thrombosis induction and subsequent observation period was higher in the groups receiving the two highest doses of fish oil. Spontaneous reflow correlated positively (p<0.013) with increasing dietary fish oil content. In conclusion, our data indicates that dietary fish oil inhibits photochemically induced thrombosis in this animal model of arterial thrombosis in a dose dependent manner.

Evidence for the cardioprotective effects of omega-3 Fatty acids

OBJECTIVE

To review available literature regarding the cardiovascular effects of marine-derived Omega-3 fatty acids and evaluate the benefit of these fatty acids in the prevention of coronary heart disease.

DATA SOURCES

Biomedical literature accessed through a MEDLINE search (1966-April 2002). Search terms included fish oil, omega-3 fatty acid, sudden death, hypertriglyceridemia, myocardial infarction, and mortality.

DATA SYNTHESIS

Following an early 1970's observational investigation that Omega-3 fatty acids may reduce the occurrence of myocardial infarction-related deaths in Greenland Eskimos, additional trials have been conducted that support this finding. Epidemiologic and clinical trial data suggest that Omega-3 fatty acids may reduce the risk of cardiovascular-related death by 29-52%. In addition, the risk of sudden cardiac death was found to be reduced by 45-81%. Possible mechanisms for these beneficial effects include antiarrhythmic properties, improved endothelial function, antiinflammatory action, and reductions in serum triglyceride concentrations. Omega-3 Fatty acids are fairly well tolerated; potential adverse effects include bloating and gastrointestinal distress, "fishy taste" in the mouth, hyperglycemia, increased risk of bleeding, and a slight increase in low-density-lipoprotein cholesterol.

CONCLUSIONS

Omega-3 Fatty acids may be beneficial and should be considered in patients with documented coronary heart disease. They may be particularly beneficial for patients with risk factors for sudden cardiac death.

Clinical trial evidence for the cardioprotective effects of omega-3 fatty acids

The notion that marine omega (w)-3 fatty acids might have beneficial cardiovascular effects was first suggested by epidemiologic studies in Greenland Inuits published in the late 1970s. These simple observations spawned hundreds of other studies, the confluence of which strongly suggests a true cardioprotective effect of w-3 fatty acids. The strongest confirmation has come from the publication of three randomized clinical trials, all of which reported benefits to patients with preexisting coronary artery disease. The most convincing of these was the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico (GISSI)-Prevezione study, in which 5654 patients with coronary artery disease were randomized to either w-3 fatty acids (850 mg/d) or usual care. After 3.5 years, those taking the w-3 fatty acids had experienced a 20% reduction in overall mortality and a 45% decrease in risk for sudden cardiac death. These findings support the view that relatively small intakes of w-3 fatty acids are indeed cardioprotective, and suggest that they may operate by stabilizing the myocardium itself.

Long-chain omega 3 fatty acids, blood lipids and cardiovascular risk reduction

Increasing evidence suggests that omega 3 fatty acids derived from fish and fish oils may play a protective role in coronary heart disease and its many complications, through a variety of actions, including effects on lipids, blood pressure, cardiac and vascular function, prostanoids, coagulation and immunological responses. Interesting differences between the effects of highly purified eicosapentaenoic acid and docosahexaenoic acid are emerging, which may be relevant in the choice of omega 3 fatty acid for incorporation into food products. On the basis of our current knowledge, we believe it is justified to recommend, particularly to high-risk populations, an increased dietary intake of omega 3 fatty acids through the consumption of fish.

Dietary cholesterol and atherosclerosis

The perceived relationship between dietary cholesterol, plasma cholesterol and atherosclerosis is based on three lines of evidence: animal feeding studies, epidemiological surveys, and clinical trials. Over the past quarter century studies investigating the relationship between dietary cholesterol and atherosclerosis have raised questions regarding the contribution of dietary cholesterol to heart disease risk and the validity of dietary cholesterol restrictions based on these lines of evidence. Animal feeding studies have shown that for most species large doses of cholesterol are necessary to induce hypercholesterolemia and atherosclerosis, while for other species even small cholesterol intakes induce hypercholesterolemia. The species-to-species variability in the plasma cholesterol response to dietary cholesterol, and the distinctly different plasma lipoprotein profiles of most animal models make extrapolation of the data from animal feeding studies to human health extremely complicated and difficult to interpret. Epidemiological surveys often report positive relationships between cholesterol intakes and cardiovascular disease based on simple regression analyses; however, when multiple regression analyses account for the colinearity of dietary cholesterol and saturated fat calories, there is a null relationship between dietary cholesterol and coronary heart disease morbidity and mortality. An additional complication of epidemiological survey data is that dietary patterns high in animal products are often low in grains, fruits and vegetables which can contribute to increased risk of atherosclerosis. Clinical feeding studies show that a 100 mg/day change in dietary cholesterol will on average change the plasma total cholesterol level by 2.2-2.5 mg/dl, with a 1.9 mg/dl change in low density lipoprotein (LDL) cholesterol and a 0.4 mg/dl change in high density lipoprotein (HDL) cholesterol. Data indicate that dietary cholesterol has little effect on the plasma LDL:HDL ratio. Analysis of the available epidemiological and clinical data indicates that for the general population, dietary cholesterol makes no significant contribution to atherosclerosis and risk of cardiovascular disease.

From Inuit to implementation: omega-3 fatty acids come of age

During the past 25 years, the cardiovascular effects of marine omega-3 (omega-3) fatty acids have been the subject of increasing investigation. In the late 1970s, epidemiological studies revealed that Greenland Inuits had substantially reduced rates of acute myocardial infarction compared with Western control subjects. These observations generated more than 4,500 studies to explore this and other effects of omega-3 fatty acids on human metabolism and health. From epidemiology to cell culture and animal studies to randomized controlled trials, the cardioprotective effects of omega-3 fatty acids are becoming recognized. These fatty acids, when incorporated into the diet at levels of about 1 g/d, seem to be able to stabilize myocardial membranes electrically, resulting in reduced susceptibility to ventricular dysrhythmias, thereby reducing the risk of sudden death. The recent GISSI (Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico)-Prevention study of 11,324 patients showed a 45% decrease in risk of sudden cardiac death and a 20% reduction in all-cause mortality in the group taking 850 mg/d of omega-3 fatty acids. These fatty acids have potent anti-inflammatory effects and may also be antiatherogenic. Higher doses of omega-3 fatty acids can lower elevated serum triglyceride levels; 3 to 5 g/ d can reduce triglyceride levels by 30% to 50%, minimizing the risk of both coronary heart disease and acute pancreatitis. This review summarizes the emerging evidence of the use of omega-3 fatty acids in the prevention of coronary heart disease.