World Journal of Cardiovascular Diseases, 2013, 3, 40-44 WJCD Published Online August 2013 (
Effects of omacor® on left ventricular remodelling
consecutive to post myocardial infarction
special issue-myocardial infarction*
Bruno Le Grand
Institut de Recherche Pierre Fabre, Castres, France
Received 26 June 2013; revised 27 July 2013; accepted 6 August 2013
Copyright © 2013 Bruno Le Grand. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Ventricular remodelling is the main trigger of the de-
velopment of heart failure. Therefore, the reduction
of structural remodelling is known to prevent the de-
velopment of heart failure. The aim of the present
study was to investigate the effects of OMACOR®, a
well known mixture of EPA and DHA in an experi-
mental model of heart failure induced by occlusion of
left descending coronary artery and the reperfusion
within 2 months. After a long term treatment of 2
months; OMACOR® (100 mg/kg) statistically signifi-
cantly reduced the expansion of infarcted zone (35%
4%, P < 0.05, n = 9, versus 45% 3% in the vehicle
group). The phosphorylation of Cx43 as biomarker of
the cardiac remodelling was visualised by immunoflu-
orescence in rat’s heart at the end of the study. In the
vehicle-infarcted group, a significant de-phosphoryla-
tion of Cx43 was observed (8.2 ± 1.0 u.a, n = 8 com-
pared to 11.8 ± 1.3 u.a in the sham group, n = 9) con-
firming a remodelling process in the infarcted group.
In the group treated with OMACOR®, the de-phos-
phorylation of Cx43 was no longer observed compar-
ed to the sham group (16.4 ± 2.9 u.a, n = 9, NS). The
present results demonstrate that a long term treat-
ment with OMA-COR® reduced the infarcted size in
experimental models of heart failure and that these
anti-remodelling effects are due at least in part by re-
synchronizing the gap junction activity.
Keywords: Left Ventricular Remodelling; Myocardial
Infarction; OMACOR®
Occlusion of the circumflex coronary artery results in ex-
tensive myocardial necrosis and fibrosis, with a decrease in
myocardial contractility and function [1-3]. Following in-
farction, the myocardium undergoes a prolonged remodel-
ling process that induces widespread structural changes,
with the ventricle becoming considerably stiffer and less
compliant [4,5]. Histologically, the most prominent chang-
es are myocyte death and scar formation in the infarcted
myocardium. The remodelling process is not limited to the
infarct area. Changes in noninfarcted myocardium include
myocyte hypertrophy, apoptosis, fiber disarray, angiogene-
sis, and an increase in interstitial collagen, all of which can
eventually lead to death from heart failure.
OMACOR®, one of the polyunsaturated fatty acid com-
pounds, has been shown to reduce cardiovascular-related
morbidity and mortality in clinical trials [6,7] and has
been demonstrated to impact cardiac remodelling, includ-
ing hypertrophy [8,9]. However, the beneficial effects of
OMACOR® on coronary artery disease are not limited to
its triglyceride-lowering function but involve various
pleiotropic effects on cardiac function including reduc-
tion of arrhythmias, inhibition of cellular proliferation
and migration, anti-inflammatory effects, and improve-
ment of endothelial function [10]. Despite the wide-
spread clinical use of OMACOR® for hypertriglyceride-
mia and prevention of coronary artery disease, data are
lacking on the effects of OMACOR® on clinical outcome
in heart failure secondary to myocardial infarction (MI).
Thus, the role of OMACOR® in heart failure due to MI
remains controversial. Therefore, the purpose of this stu-
dy was to determine whether administration of OMA-
COR® during the peri-infarct period attenuates the pro-
gressive LV chamber dilatation and contractile dysfunc-
tion in a rat model of MI.
2.1. Preparation of Animals
*Competing interests statement: Bruno Le Grand is an employee of In-
stitut de Recherche Pierre Fabre. The experiments were carried out according to French
B. Le Grand / World Journal of Cardiovascular Diseases 3 (2013) 40-44 41
law and the local ethical committee guidelines for animal
Male Sprague-dawley rats weighing 220 - 300 g at the
date of the experiments were purchased from Iffa Credo
(France). They were housed in the Centre de Recherche
Pierre Fabre animal facilities for at least two weeks be-
fore use. Throughout this period, they had free access to
food and drinking water. The animal house was maintain-
ed on a 12-h light/dark cycle (lights on at 7 a.m.) at an
ambient temperature of 20˚C ± 2˚C.
2.2. Surgical Model of Myocardial Infarction
The rats were anesthetized using Isoflurane 3% on O2.
Then, the animals were intubated and ventilated at 60 re-
spirations/min (2.5 ml/respiration, Ventilator model 683,
Harvard Apparatus, HOLLISTON, MA, USA) while anes-
thesia was maintained. Body temperature was maintained
at 37˚C by a heating pad (Homeothermic blanket control
unit, Harvard Apparatus, HOLLISTON, MA, USA). A
left thoracotomy was performed and a silk suture (4.0)
was placed around the left coronary artery ~1 mm from
its origin. Both ends of the silk thread were passed through
a polyethylene tube. The left coronary artery was occlu-
ded by pressing the polyethylene tube against another
polyethylene tube placed on the heart. After 30 min of
ischemia, the polyethylene tube was removed to initiate a
definitive reperfusion phase. Then, the thorax was closed
and the animals regained consciousness 1 hour after the
end of the ischemia. Finally, the reperfusion was perform-
ed for 2 months in conscious animals. Then, OMACOR®
or vehicle (olive oil) was daily administrated orally by
gavage using a single administration of 100 mg/kg.
2.3. Histological Analysis and
Immediately after the sacrifice, the heart was rapidly ex-
cised and fixed with AFA (alcohol, formaldehyde, ace-
tate) for 1 - 4 days. The ventricles were cut into five
cross-sectional samples of 2 mm each. The five regions
were then processed into paraffin with an automated tis-
sue processor. The samples were then embedded into
fresh paraffin with the apical side down. From the third
block of tissue, a 3 µm section was cut and was used for
Masson staining. The stained slide was then hydrated
with distilled water and then incubated twice with 100%
ethanol (for 1 min each).
Masson stainings were used to quantitate interstitial
collagen volume fractions as well as infarct sizes using a
video image analysis system (LEICA QWIN, LEICA
Imaging Systems Ltd., Cambridge, England). A color vi-
deo camera (DXC-390P color videocamera, SONY, Paris,
France) relayed the image to a computer through LEICA
analysis software application. The following parameters
were measured (in mm): septal wall, left ventricular free
wall, endocardial and epicardial left ventricular circum-
ference and endocardial and epicardial infarcts. The green
color extraction was used to quantitate interstitial colla-
gen. The equation used to calculate infarct size was the
following: percent infarct of left ventricle = [epicardial
infarct (in mm) + endocardial infarct (in mm)]/[LV epi-
cardial circumference (in mm) + LV endocardial circum-
ference (in mm)] × 100 (Sandmann et al., 2001).
The phosphorylation of connexion 43 (Cx43) at inter-
calated disks of atrial myocardium was determined by im-
munofluorescence. After the sacrifice, the atria were col-
lected and immediately immerged in Formalin solution
(Sigma-Aldrich, HT50-1-2) for 10 - 15 minutes at room
temperature. They were then washed three times for 10
minutes in tyrode buffer, mounted in embedding medium
(Miles), frozen in isopentane precooled in liquid nitrogen,
and stored at –80˚C. Immunostaining was performed on
7-µm-thick cross-sections. Tissue sections were perme-
abilized and saturated with 0.5% Triton X-100, 1% BSA
and 10% of goat, chicken and human serum in phosphate
buffered saline (PBS) for 60 minutes. They were then
labeled with mouse antibody to α-actinin (1:400, Zymed)
or rabbit phosphospecific antibodies to P-Ser368-Cx43
(1:50, Life Technologies) in PBS containing 1% BSA,
0.5% Triton X-100 and 3% of goat, chicken and human
serum for at least 2 h at room temperature. After washing
in PBS, Alexa 488-conjugated chicken anti-mouse IgG
and/or Alexa 594-conjugated goat anti-rabbit IgG (1:400,
Life technologies) were added with 1% BSA and 3% of
goat, chicken and human serum in PBS for 1 hour. After
washing in PBS, coverslips were mounted with Dako
fluorescent mounting medium. For the quantification of
Cx43 phosphorylation, the images were captured with
Olympus BX 50 microscope and DP50 camera with mag-
nification 200 and a similar time exposure for all the
atrial cross-sections studied. Treatment of images and
quantification of phospho-Cx43 labeling at the interca-
lated disks were performed with NIH Image J software
program. The mean fluorescence intensity was counted
on 10 intercalated structures by field and on 6 fields for
each rat.
Images of Figure 1(a) were captured at magnification
600 and similar time exposure with an Olympus IX 50
microscope and a Roper Scientific camera. Images were
automatically collected at 0.2 μm Z-intervals with a pie-
zoelectric translator (PIFOC, Karlsruhe/Palmbach, Ger-
many) driven by Metamorph Software (Universal Imag-
ing Corp., Downingtown, PA). Each Z-series was decon-
voluted automatically using a measured Point Spread
Function and an adapted constrained interactive de-con-
volution algorithm. Treatment of images was performed
with the NIH Image J software program. Sets of three
consecutive z-images were compiled and treated with
Copyright © 2013 SciRes. OPEN ACCESS
B. Le Grand / World Journal of Cardiovascular Diseases 3 (2013) 40-44
similar thresholds for each condition.
2.4. Statistical Analysis
Statistical analysis of data was performed using SPSS®
software version 16.0, P < 0.05 was considered statisti-
cally significant, and Bonferroni’s post hoc test was used
where appropriate. Continuous data were expressed as
mean ± S.E. mean, and comparisons between treatment
groups were made with one-way ANOVA. The incidence
of AF was compared with Fisher’s exact test.
3.1. Infarcted Ventricular Histology
Figure 1(a) shows typical ventricular stained slides ob-
tained 2 months after myocardial infarction. As expected,
no infarction and no collagen deposition were detected in
all sham-operated animals (Figures 1 (a)-(c)). The vehi-
cle exhibited infarct expansion, late-phase ventricular di-
lation and fibrosis (green staining) of viable myocardium,
which is consistent with known post myocardial infarct
tissue remodelling (Figure 1(a)). Indeed, the percentage
of the infarcted left ventricle was 45% 3% (n = 7; Fig-
ure 1(c)). The collagen deposition in this group was lar-
gely increased (22 4 mm2), and the free wall thinning
induced a significant reduction of thickness ratio (0.63
0.05). OMACOR® (100 mg/kg) statistically significantly
reduced the expansion of infarcted zone (35% 4%, P <
0.05, n = 9, versus 45% 3% in the vehicle group; Fig-
ure 1(c)). Despite a large tendency, OMACOR® failed to
significantly reduced scare collagen deposition at the late
time point (20 2 mm2, NS, Figure 1(b)).
3.2. Cardiac Tissue Remodelling
Phosphorylation of Cx43 as biomarker of the cardiac re-
modelling [11] was visualised by immunofluorescence in
rat atria at the end of the study and quantified using the
image J software. In the olive oil-infarcted group (vehi-
cle), a significant de-phosphorylation of Cx43 was ob-
served as shown in Figure 2 (8.2 ± 1.0 u.a in the olive
oil group, n = 8 compared to 11.8 ± 1.3 u.a in the sham
group, n = 9) confirming a remodelling process in the in-
farcted group. In the infarcted group treated with OMA-
COR®, the de-phosphorylation of Cx43 was no longer
observed compared to the sham group (16.4 ± 2.9 u.a, n
= 9, NS, Figure 2). Similarly, the phosphorylation of
Cx43 was statistically significantly restored between the
olive oil group and OMACOR® groups.
Collectively, these data indicate that the marked dila-
tion of the heart cavities that occurring in the olive oil
group following 2 months after infarction and reperfu-
sion was markedly reduced by a daily oral treatment with
OMACOR® (100 mg/kg).
Infarct size
Collagen area
Sham VehicleOMACOR
*** *
Sham VehicleOMACOR
*** n.s.
(a) (b)
Figure 1. (a) Ventricular transaxial plane showing Masson stai-
ning of a ventricular slice after 30 min left-descending coronary
occlusion and 2 months of reperfusion. Upper, Sham operated
rat. Middle, vehicle-treated rat (olive oil). Lower, OMA-COR®
-treated rat (100 mg/kg). The viable zone is red, the ischemic
zone is white, and the collagen is green. Bar graph showing the
collagen area (b) and the infarcted zone (c) in the sham oper-
ated group, in the presence of vehicle (olive oil), and OMA-
COR®. Data are means SEM. *P < 0.05 and ***P < 0.001.
shamvehicle OMACOR
Phos pho -co nn e xin43 (u.a.)
Phospho-connexin 43
Figure 2. Bar graph showing the left atria size quantified by
echocardiography (a) posphorylation of Cx43 quantified by
immunostaining (b) in the sham operated group, in the presence
of vehicle (olive oil), and OMACOR®. Data are means SEM.
*P < 0.05, **P < 0.01. n.s: non-significant.
Copyright © 2013 SciRes. OPEN ACCESS
B. Le Grand / World Journal of Cardiovascular Diseases 3 (2013) 40-44 43
The key finding of this study was that a 2-month treat-
ment with OMACOR® led to a significant reduction in
left ventricular remodelling implicated in the develop-
ment of heart failure. To the best of our knowledge, no
prior studies have demonstrated the long term effects of
OMACOR®, alone on all of these parameters of heart
founction. In the present rat model of ischemia-induced
heart failure, OMACOR® (100 mg/kg) reduced the ex-
pansion of the ventricular infarcted zone which was asso-
ciated with a decrease of the heart remodelling and of the
dephosphorylation of Cx43.
The cardioprotective effects of n-3 PUFA appear to be
due not through a single mode of action but to a syner-
gism between multiple, intricate mechanisms that involve
TG lowering, anti-inflammatory, inflammation-resolving,
regulation of transcription factors and gene expression,
membrane fluidity and antiarrhythmic and antithrombo-
tic effects [12,13]. Both EPA and DHA components of
OMACOR® have similar yet very distinctive cardiopro-
tective properties. Only DHA seems to decrease blood
pressure, heart rate and the number of total and small
dense LDL particles. DHA also has higher potency to re-
gulate the activity of several transcription factors than
EPA [12,13]. The present results demonstrate that OMA-
COR® (100 mg/kg) reduced the infarct size and induced a
significant reduction of the ventricular dilation for 2
months after myocardial infarction. This cardioprotection
mediated by OMACOR® was associated with a partial
reduction of the collagen scar suggesting that the com-
pound could preserve the remodelling of heart tissue con-
secutively to myocardial infarction. Our findings that
OMACOR® reduces left ventricular dilation after myo-
cardial infarction are in agreement with previous findings
demonstrating that PUFAs reduce heart failure induced
by myocardial infarction in dog [14], as well as in rat with
left ventricular pressure overload [13]. These protective
effects of OMACOR® on post myocardial infarction in-
duced ventricular dysfunction are associated with a de-
crease of myocardial remodelling and alterations of Cx43
phosphorylation. Thus, two months after surgery, the in-
farcted rats had a left ventricular dysfunction and an en-
larged and fibrotic left ventricle. It has been previously
shown that regression of the heart remodelling in treated
myocardial infracted rats was associated with re-phos-
phorylation and assembly of organized gap junction [11].
Thus, in the vehicle group, the large proportion of Cx43
was non-phosphorylated. Because the phosphorylation
sites regulate channel properties, assembly and targeting
in junctional plaques [15], the dephosphorylated Cx43
from remodelling heart is responsible for depressed cell-
cell coupling [11]. Therefore, the reduction of a higher
amount of non-phosphorylated Cx43 by OMACOR® and
the redistribution of Cx43 suggest a re-organisation of
junctional areas in heart tissue. Collectively, this cardio-
protection of OMA-COR® against the dephosphorylation
of Cx43 and the prevention of the atria and ventricle di-
lations certainly contribute to cardioprotective properties
against structural remodelling-induced heart failure.
It is becoming increasingly clear from clinical and ani-
mal studies that OMACOR® alters cardiac membrane pho-
spholipid fatty acid composition, decreases the onset of
new HF, and slows the progression of established HF [6,
7]. This effect is associated with decreased inflammation
and improved resistance to arrhythmia incidence. That
said, there has yet to be a definitive clinical trial with an
appropriately high dose of OMACOR® (>3 g/d) or com-
paring DHA to EPA in established HF. Definitive infor-
mation on the optimal dose of OMACOR® is not avail-
able; thus additional clinical trials are warranted.
In summary, OMACOR® is a potent mixture of EPA +
DHA with a high potential for the treatment of heart
failure induced myocardial infarction. Indeed, the present
results demonstrate that a long term treatment with
OMACOR® reduces the ventricular dilation and the in-
farcted size in experimental models of heart failure. The
present study demonstrates that these anti-remodelling ef-
fects are due at least in part by resynchronizing the gap
junction activity beside the well-established cardiopro-
tective mechanisms of the PUFAs.
I am indebted to my colleagues in the Division of Cardiovascular Dis-
eases II for performing the experimentations described in the present
manuscript. I thank E. Dupeyron-Martel for secretarial assistance.
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