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BERLIN, ET AL.
mid RCA only because a stent could not pass distally
due to a sharp bend. This patient experienced subacute
occlusion of the RCA with a thrombus including the
distal and mid RCA.
There were three cases of cardiac death during
6-month follow-up; one patient died 2 weeks after hos-
pitalization in another hospital (no further details avail-
able); another patient had stopped clopidogrel because
of an allergy and died from acute MI; and the third
patient died at home (two weeks after hospitalization
for pulmonary edema). Another two patients died be-
tween 6th and 12th month of follow-up; one of them
with severe left ventricle (LV) dysfunction was hos-
pitalized because of pulmonary edema, intubated, and
died due to multiple organ failure; and another patient
was admitted for chest pain, was scheduled for ambu-
latory thallium scan, and died at home. Four patients
died from noncardiac reasons: two from severe pneu-
monia, one from septic foot, and one from metastases
of prostatic carcinoma.
Discussion
Drug-eluting stents (DES) have reduced in-stent
restenosis and TLR rate compared to BMS,
11–13
but
recent reports of late thrombosis
14
have reignited in-
terest in BMS. Recent publications on stents coated
with biologically inert material have reported resteno-
sis and TLR rates approaching those of DES.
15–17
In
this study
,
we investigated the short- and long-termout-
comes of Prokinetic BMS in patients presenting with
ACS. The results were exceptionally good including
a low rate of TLR (2.6% at 6 and 12 months) and
MACE (8.5% and 11.1% at 6 and 12 months, respec-
tively). In comparison, previous studies in ACS have
reported clinical TLR ranging from 11% to 14% and
MACE ranging from 16% to 21%.
18
,
19
Stent material
and design are considered important factors in deter-
mining restenosis rate. Stainless steel (316L alloy) was
the most prevalent in the early days. Release of nickel
and molybdenum ions from stainless-steel stents was
implicated in causing allergic reaction and inducing
in-stent restenosis.
6
Fujimoto et al. have shown that
implantation of a nonferromagnetic cobalt-chromium
based alloy in AMI patients provided better outcome
than old-type stainless steel BMS (TLR rate 5.1%
and 16.0%, respectively [P
=
0.016]).
20
In a recent
study, Rittersma et al. have shown that thinner-strut
stents significantly reduce angiographic and clinical
restenosis after coronary intervention (17% and 11%,
respectively) with the use of various generations of
bare Multilink stents.
21
Stents with helical design are
promoted for their combination of flexibility and radial
force.
Stent surface contributes to vascular responses, in-
cluding platelet and leukocyte deposition followed by
smooth muscle cell migration, proliferation, and pro-
duction of extracellular matrix manifesting as neointi-
mal hyperplasia. Stent coating might play a role in late
angiographic and clinical outcomes. Specifically, sili-
con carbide coating has been shown to accelerate stain-
less steel endothelialization in vitro.
22
Although previ-
ous clinical studies with silicon carbide coating yielded
conflicting results,
23–25
a recent study by Dahm et al.
has shown encouraging clinical outcome and low rate
of TLR (4.9%) and MACE (5.6%) at 6 months in a co-
hort of patients with diffuse coronary artery disease that
were treated with Prokinetic.
26
These favorable results
may be attributable to the more rapid endothelialization
of the stent as shown in vitro. However, only 19.3% of
these patients had non-ST-elevation myocardial infarc-
tion (NSTEMI) or ST-elevation myocardial infarction
(STEMI). The clinical setting is important in determin-
ing whether or not restenosis might occur. The patho-
physiology of the unstable plaque is different from that
of stable atherosclerotic lesion.
27
Several studies have
suggested that the mechanism of in-stent restenosis af-
ter BMS implantation for acute MI is also different
from stable angina pectoris patients.
28
,
29
Tanaka et al.
used intravascular ultrasound to investigate the correla-
tion between lesion morphology and in-stent restenosis
and found that ruptured plaques were predictive of in-
stent restenosis after primary stenting in patients with
acute MI. They hypothesized that the inflammatory
components of the ruptured plaque, mainly the lipid
core, may enhance inflammatory response, resulting in
increased neointimal proliferation.
29
In the present study we found a low rate of TLR
and MACE despite high-risk clinical profile including
ACS.
Study Limitations.
This study was a single-center
retrospective with a small number of patients and non-
blinded outcome assessment with possible selection
bias. A randomized study with a larger patient popula-
tion is needed to confirm the results. In summary, the
clinical outcomes at 6 and 12 months after Prokinetic
stent implantation are excellent and may be attributable
to its unique combination of metal alloy, helical de-
sign, and silicon carbide coating. New generation BMS
380
Journal of Interventional Cardiology
Vol. 23, No. 4, 2010