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Kyoichi Mizuno, M.D., Kimio Satomura, M.D.,
Akira Miyamoto, M.D.,Koh Arakawa, M.D.,
Toshio Shibuya, M.D., Tsunenori
Arai, Ph.D.,Akira
Kurita, M.D., Haruo Nakamura,
M.D.,
and John A. Ambrose, M.D.
(Abstract)
Background
. Disruption of an atherosclerotic
plaque
in a coronary artery followed
by the formation
of
a thrombus is believed to be
the cause of
both unstable angina and acute
myocardial
infarction.
Although thrombolytic therapy
is efficacious
in patients with acute myocardial
infarction,
for unknown reasons it is far
less effective
in patients with unstable angina.
We postulated
that there might be differences
in the composition
of the coronary-artery thrombi
in unstable
angina and acute myocardial infarction.
Methods.
To investigate the appearance
of coronary
artery thrombi, we performed
percutaneous
transluminal coronary angioscopy
in 15 patients
with unstable angina and 16 with
acute
myocardial infarction. Angioscopy
was performed
within 48 hours after an episode
of pain
at rest in the patients with
unstableangina
and within 8 hours of onset in
those with
acute
myocardial infarction.
Results.
Angioscopy revealed coronary
thrombi in all
but two patients (one in each
group). Of
the 29
patients with thrombi, those
with unstable
angina were frequently observed
to have
grayish-white thrombi (10 of
14, 71 percent),
but none were seen in the 15
patients with
acute
myocardial infarction (P <
0.01).
By contrast, reddish thrombi
were observed
in all 15 patients with acute
myocardial
infarction
who had thrombi, but in only
4 of the 14
patients with unstable angina
and thrombi
(P < 0.01). As assessed by
coronary angiography,
occlusive thrombi occurred frequently
in
patients with acute myocardialinfarction
(13 0f 16 patients) but were
not seen in
any of
the 15 patients with unstable
angina (P <
0.01).
Conclusions.
Coronary-artery thrombi play
an important
part in the pathogenesis of unstable
angina
and
acute myocardial infarction.
However,the
appearance of the thrombi is
different in
the two
conditions,possibly reflecting
differences
in the composition or age of
the thrombi
or
the presence or absence of blood
flow in
the artery. This difference may
account for
the contrasting results of thrombolytic
terapy.
(The New England Journal of Medicine 1992;326:287-91)
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