Taking omega-3 fatty acids appeared
to lower inflammation and guard against further declines in heart function
among recent heart attack survivors already receiving optimal standard care,
according to results from a randomized, controlled trial to be presented at the
American College of Cardiology's 64th Annual Scientific Session in San Diego.
Patients in the study taking 4 grams
of prescription-only omega-3 fatty acid capsules daily for six months after a
heart attack were significantly more likely to show improvements in heart
function compared to patients taking a placebo. Heart function was measured by
an expansion of the left ventricular endsystolic volume index. Patients taking
omega-3 fatty acids also had significantly less evidence of fibrosis -- a
thickening or scarring of the areas of the heart remote from the heart attack,
which can develop when the surviving heart muscle works harder and under high
pressure to compensate for the damage to the heart. The data suggests that
patients who were able to mount a substantial change in levels of omega-3 fatty
acids in their blood derived the most benefit.
"Giving a high dose of omega-3
fatty acids soon after a heart attack appears to improve cardiac structure and
heart functioning above and beyond the standard of care," said Raymond W.
Kwong, M.D., M.P.H, director of cardiac magnetic resonance imaging at Brigham
and Women's Hospital in Boston and the study's senior author. "Because
this is a unique group of patients with remarkably high adherence to
[guideline-directed] treatments for acute myocardial infarction already, we
feel fairly confident that the benefits from this therapy are additive. The
implications of this study could be fairly large."
An estimated 720,000 Americans have
heart attacks each year. After a heart attack, the heart can remodel or
reorganize itself to maintain or improve function. In some cases, the heart may
undergo adverse changes such as enlargement of the heart, decreased pumping
ability or added cardiac strain that can predispose someone to heart failure
and arrhythmias later in life.
Although earlier studies have shown
that omega-3 fatty acids may lower the risk of irregular heartbeats and death
from a heart attack, research has not consistently shown a benefit. Kwong said
his research is the first to use quantitative cardiac imaging to look at how
omega-3 fatty acids might actually protect the heart after a major heart
attack.
Researchers randomized 374 patients
recovering from a heart attack and receiving standard treatment to take either
4 grams of omega-3 fatty acids or a placebo; groups were balanced in terms of
location of the infarct--anterior or non-anterior--and age. Blood work and
cardiac imaging were analyzed at two to four weeks post-heart attack and again
at six months. Compared to previous research, this study used a much higher
dose of omega-3 fatty acids, 4 grams compared to 1 gram daily, and a small
amount of corn oil, which does not contain fatty acids, as the placebo.
By using cardiac magnetic resonance
imaging, researchers were able to look at changes in patients' hearts and see
the disease process before and after treatment. Adverse changes in left
ventricular remodeling and function, in addition to the worsening of fibrosis,
were used as surrogates for poor outcomes after heart attack.
Patients taking the omega-3 fatty
acids were 39 percent less likely to show a deterioration of heart function as
compared to patients taking a placebo. The analysis also looked at key markers
of systemic inflammation, which were also more likely to be improved in those
taking the fish oil. In particular, the percent reduction in ST2, a marker of
the severity of adverse cardiac remodeling and tissue fibrosis, was
substantially greater in the treatment arm after six months.
"Omega-3 fatty acids may have
anti-inflammatory effects and also promote better cardiac healing," Kwong
said. "This is important because other anti-inflammatory agents, including
steroids and NSAIDS, have failed to make a difference after myocardial
infarction." Patients in the study who had a 5 percent increase in the
amount of omega-3 fatty acid in their blood seem to have the best chance of
improving heart function.
"If this becomes a useful
therapy, it seems a 5 percent increase in the serum level of omega-3 fatty
acids correlates with a 10 percent improvement in left ventricular
remodeling," he said. In this study, most (92 percent) of patients
randomized to fish oil increased omega-3 fatty acid by at least 5 percent,
compared with less than half (42 percent) of patients receiving placebo.
Kwong said the higher-dose omega-3
fatty acids was not found to be associated with any major safety issues, such
as increased bleeding. "It's a very well-tolerated therapy," he said,
adding that it is unlikely patients could get the amount of omega-3 fatty acids
from diet alone. He said the daily 4 gram dose is roughly equivalent to someone
eating a large, 8-ounce serving of salmon every day for six months.
For many years, the American College
of Cardiology and the American Heart Association have recommended that people
eat fish rich in omega-3 fatty acids at least twice a week because of its
potential heart benefits.
Kwong said most North Americans do
not follow this advice, while Japanese populations with higher levels of
omega-3 and an otherwise similar risk profile to North Americans have lower
risks of heart disease and sudden cardiac death. The increase in the omega-3 blood
content of many patients in Kwong's study at six months was similar to levels
found in Japanese populations with a diet very rich in omega-3 fatty acids.
Fatty fish such as salmon, tuna, trout and sardines
contain the most omega-3 fatty acids. Fatty acids are a key component of cell
membranes and they help with cell signaling, proper immune function and may
also improve cognitive functioning. This study is limited in that it did not
investigate the association between omega-3 fatty acids and cardiac events
after heart attack; assessing this relationship would require a large group of
patients over many years. It also did not evaluate this treatment immediately
after having a heart attack.
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