Intravascular Ultrasound
(IVUS) Imaging Reveals Hidden Heart Attack Culprit In Women
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Angiography
image (L) shows a normal left
circumflex artery (arrow) but an IVUS image (R)
of the same segment
reveals a plaque disruption
that caused
a heart attack |
October 6, 2011 -- A
heart attack can occur in a coronary artery that looks completely normal
on angiography, long considered the "gold standard" of coronary imaging.
But newer techniques, such as intravascular ultrasound (IVUS)
and cardiac magnetic resonance (CMR) imaging, were
able
to reveal
the cause
of the
incident: plaque
disruption.
Such is the conclusion of a new study
by researchers at the Cardiac & Vascular
Institute at NYU Langone Medical Center. And this type of non-obstructive
myocardial infarction seems to happen more frequently in women than
in men.
As seen in this image, a coronary
artery may look completely normal using the standard two-dimensional
"shadow" image of coronary angiography. But when the same
arterial segment is viewed cross-sectionally using intravascular
ultrasound, a "flap" of
plaque can be seen hanging in the arterial lumen. This plaque disruption,
a rupture
or ulceration of cholesterol plaque,
was shown to be the mechanism behind myocardial infarction
(heart attack) in some women who were classified as having no
significant coronary artery disease (CAD). The study, "Obstructive
Coronary Artery Disease Mechanisms of Myocardial Infarction in Women
Without Angiographically Obstructive Coronary Artery Disease" was
published in the September 27th issue of the journal Circulation.
The research team, led by Dr. Harmony
Reynolds of NYU Langone, investigated the origin of heart
attacks in fifty
women
with "normal"
coronary arteries, as seen on angiography. Using intravascular
ultrasound (IVUS), they found that
almost 40% of the women showed evidence of plaque disruption -- something
that cannot be seen on an angiogram. When the results of
cardiac magnetic resonance (CMR) imaging were added, 70% of the women
were found to have abnormalities not detectable during angiography.
As shown by the PROSPECT
study of over 700 patients, published in the New
England Journal of Medicine in January, IVUS was been able to
identify so-called "vulnerable
plaques" that are invisible on angiograms. Dr. Reynolds opined
that her study "knitted together" some of the PROSPECT results. She
commented to Angioplasty.Org:

Harmony Reynolds,
MD |
"We know from PROSPECT that lesions
that are ultimately going to be culprits were non-obstructive and looked
vulnerable
on IVUS.... Angiography
unfortunately doesn't tell the
whole story and I think IVUS is a fantastic tool to be able to learn
more about the artery wall in all kind of conditions. And this MI
with non-obstructive disease is definitely one of them."
Dr. Reynolds' thoughts are that it is possible
that these plaque disruptions may cause a thrombosis, especially in
women, because of hormonal
and other gender-specific differences, but that the body then lyses
this thrombotic blockage naturally and, by the time the patient is
in the cath lab, the blockage is gone...but the heart attack is very
real.
“Women who have had a heart attack and have normal or near-normal angiogram results may be told they didn’t have a heart attack at all because of the angiogram result,” said Reynolds. “Our
study shows the benefit of additional imaging to find a plaque disruption
when it occurs and correctly diagnose the reason for heart attack in
these women.”
The clinical and treatment implications
of this study are significant because many heart
attack
patients
without
angiographically
obstructive coronary artery disease may go undiagnosed and not receive
the necessary heart medications like antiplatelet drugs and statins
-- lifesaving tools against future cardiac events.
Dr. Reynolds continued:
"I think, if plaque rupture is the
culprit in a substantial portion of them which we've shown, then
if it's the same cause it should be
the same medicine. We can do a lot better -- there's a big way to
go from telling people that they didn't have a heart attack at
all towards
treating everybody with proven medications. And that's what I would
like to see this do...definitely aspirin and statins, maybe beta-blockers,
maybe even thienopyridines.
"Myocardial
infarction without CAD that appears to be significant on an angiogram
is more common than many people think. Patients
and doctors both need to know there is a form of heart attack that
can occur in which the arteries are not blocked on an angiogram.
This is in fact a heart attack and steps need to be taken to prevent
another
cardiac event.”
About the Intravascular Guidance Center
on Angioplasty.Org
To assist in educating the professional and patient population in the U.S.
about these new imaging, measurement and therapetic techniques,
Angioplasty.Org created the "Intravascular
Guidance Center" in
2006: a special section which is devoted to information and news for both patients
and physicians about intravascular ultrasound (IVUS), fractional flow reserve
(FFR),
optical
coherence
tomography
(OCT) and other intravascular modalities.
The Intravascular Guidance Center
features overview articles, the latest news and interviews with leading
practitioners of these techniques, such as Drs. Antonio Colombo, John McBarron
Hodgson, Augusto
Pichard,
William
Fearon
and Nico Pijls.
This special section receives support from
Volcano Corporation.
Reported by Burt Cohen, October 6, 2011
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