Lower Risk of Heart Failure Linked to Higher Blood EPA Concentrations
In congestive heart failure, the heart is unable to pump sufficient blood for the rest of the body’s needs. The condition can develop as a result of coronary artery disease, high blood pressure, obesity, diabetes or other disorder. About 75% of patients with heart failure have hypertension, with a previous myocardial infarction posing nearly as great a risk. The American Heart Association estimates that approximately half the people diagnosed with heart failure die within 5 years. After the age of 40, the chance of developing heart failure is 1 in 5 for both men and women. These grim statistics underlie the urgency of finding effective prevention strategies.
Several studies have reported a lower risk of developing congestive heart failure among those with higher intakes of fish or long-chain omega-3 PUFAs (n-3 LC-PUFAs). For example, higher plasma DHA levels or the consumption of 5 or more fish meals per week were associated with a significantly lower risk of heart failure in women; eating tuna or other broiled or baked fish was associated with a lower incidence of heart failure in older men and women. Others reported no association between fish or n-3 LC-PUFA consumption and incident heart failure in older adults.
The August 2011 issue of this newsletter described two reports in which higher consumption of baked or broiled fish was associated with a lower risk of heart failure in women and high-dose n-3 LC-PUFAs were related to increased left ventricular ejection fraction in patients with severe chronic heart failure of nonischemic origin. Diverse data are accumulating to suggest that n-3 LC-PUFAs may be beneficial in reducing the risk of heart failure or improving heart function in patients who have it.
The difficulty in obtaining accurate estimates of the consumption of n-3 LC-PUFAs from food frequency questionnaires plagues many dietary studies. Estimating the n-3 LC-PUFA status of study participants using biomarkers is preferable, but more costly. This report, using fatty acid data collected in the Cardiovascular Health Study, looked at the relationships between incident congestive heart failure and plasma phospholipid concentrations of EPA, docosapentaenoic acid (DPA n-3) and DHA in 2,735 participants randomly selected from those without heart failure or coronary heart disease for whom blood samples were available. Participants ranged in age from 45 to 64 years. They were monitored annually for up to 14 years after enrolment, with confirmation of congestive heart failure assured by 3 criteria: diagnosis of the treating physician, disease symptoms or supportive clinical findings and medical therapy (diuretics plus digitalis or ACE-inhibitors or long-acting nitrates).
The investigators determined the relative risk for incident heart failure using Cox proportional hazards models, with time at risk until the first diagnosis, death or latest adjudicated follow-up in 2006. Adjustments were made for demographic, cardiovascular and lifestyle risk factors. The key finding was an inverse association between the highest and lowest quartiles of plasma phospholipid EPA and a significantly lower risk of congestive heart failure over 14 years (multivariate hazard ratio = 0.52, 95% CI = 0.38 – 0.72, P for trend = 0.001). Total n-3 LC-PUFAs, DPA and DHA were not significantly associated with a reduced risk of heart failure, but the trend for each was toward a lower risk.
When the hazard ratios were analyzed at the mid-point of follow-up after 7 years, multivariate analysis showed that EPA (50%), DPA (40%), DHA (35%) and total n-3 LC-PUFAs (50%) were each associated with a lower risk of congestive heart failure, as shown in the Table. Adjustment for fish consumption had no appreciable effect on the risk ratios. The risk of heart failure was only modestly reduced with greater fish consumption and did not vary by age, sex or drug-treated hypertension. However, the inverse association between DHA and heart failure appeared more pronounced with age. The investigators also reported that individual fatty acid concentrations were inversely associated with physiologic risk factors for heart failure, but that specific relationships varied. For example, DHA was associated with a lower heart rate and a trend to lower systolic blood pressure, but not with other risk factors.
Table. Multivariate-adjusted risk (hazard ratios) of incident congestive heart failure over 7 years among 2,735 adults by plasma phospholipid EPA, DPA, DHA and total n-3 LC-PUFA concentrations
In this study, the strongest associations for reduced risk of congestive heart failure were observed with the highest plasma phospholipid concentrations of EPA. Interestingly, the risk of heart failure was not associated with DHA concentrations, even though DHA is 5- to 10-fold more abundant in the heart than EPA. The authors suggest that each of these fatty acids may have distinct but complementary effects on heart health, with EPA having stronger effects on nonfatal cardiac events, such as unstable angina and nonfatal myocardial infarction, and DHA protecting against fatal arrhythmias. The lack of association between heart failure and fish consumption may also be related to DHA, which is more strongly related to fish consumption than EPA. As data accumulate showing a lower incidence of congestive heart failure with higher consumption or blood phospholipid n-3 LC-PUFA concentrations, the importance of these fatty acids for the prevention of heart failure may become more compelling.
Mozaffarian D, Lemaitre RN, King IB, Song X, Spiegelman D, Sacks FM, Rimm EB, Siscovick DS. Circulating long-chain ω-3 fatty acids and incidence of congestive heart failure in older adults: the cardiovascular health study: a cohort study. Ann Intern Med 2011;155:160-170. [PubMed]