Subacute Stent Thrombosis in the Era of Intravascular
Ultrasound-Guided Coronary Stenting Without Anticoagulation:
Frequency, Predictors and Clinical Outcome
ISSAM MOUSSA, MD, CARLO DI MARIO, MD, FACC,* BERNHARD REIMERS, MD,*
TATSURO AKIYAMA, MD,* JONATHAN TOBIS, MD, FACC,† ANTONIO COLOMBO, MD, FACC*
New York, New York; Milan, Italy; and Irvine, California
Objectives. This study was performed to determine predictors of
subacute stent thrombosis (SST) in the era of intravascular
ultrasound (IVUS)-guided coronary stenting without anticoagula-
Background. The incidence of stent thrombosis has declined
with the application of high pressure stent deployment with only
antiplatelet therapy. However, no data are available on predictors
of stent thrombosis in this era.
Methods. Between March 30, 1993 and July 31, 1995, 1,042
consecutive patients underwent coronary stenting without antico-
agulation. For this analysis, we excluded patients who underwent
coronary artery bypass surgery, died or had acute stent thrombo-
sis within the 1st 24 h after stenting (41 patients). A total of 1,001
patients (1,334 lesions) were included: 982 patients (1,315 lesions)
without SST and 19 patients (19 lesions) with SST.
Results. The rate of SST was 1.9% (per patient). There was no
difference between the SST and No SST groups in rescue stenting
(12% vs. 13.5%, p ? 1.0) or mean ? SD reference diameter (3.11 ?
0.58 vs. 3.19 ? 0.53 mm, p ? 0.54). A preexisting thrombus was
present in 12% of the SST group and in 4.5% of the No SST group
(p ? 0.19). Predictors of SST by univariate analysis were low
ejection fraction (p ? 0.004), more stents per lesion (p ? 0.049),
use of combination of different stents (p ? 0.012), smaller balloon
size (p ? 0.012) and suboptimal result in terms of smaller lumen
dimensions by angiography (p ? 0.016) and IVUS (p ? 0.004),
residual dissections (p ? 0.027) and slow flow (p ? 0.0001). In
stepwise logistic regression analysis, ejection fraction (p ? 0.019),
use of a combination of different stents (p ? 0.013) and postpro-
cedure dissections (p ? 0.014) and slow flow (p ? 0.0001) were
predictive of SST.
Conclusions. In the present era of stent implantation, factors
that may predispose to SST are low ejection fraction, intraproce-
dural complications leading to utilization of more stents, partic-
ularly with different stent designs, and suboptimal final result in
terms of smaller lumen dimensions and persistent slow flow and
(J Am Coll Cardiol 1997;29:6–12)
?1997 by the American College of Cardiology
Coronary stenting has been shown to reduce the morbidity of
acute vessel closure (1) and to decrease clinical and angio-
graphic restenosis in selected lesions (2,3). However, the rate
of subacute stent thrombosis (SST) and vascular complications
remained high in the era of low pressure stent deployment
despite vigorous anticoagulation (4–6). Intravascular ultra-
sound (IVUS) guidance provided the insight that led to the
application of high pressure stent deployment. These technical
refinements have been shown (7,8) to decrease the rate of SST
despite the use of antiplatelet therapy alone. Although the
incidence of SST is reduced, limited data are available on
predictors of SST with this new approach. This report presents
a retrospective analysis of our experience, using a data base
that was collected prospectively, in an attempt to highlight the
factors associated with SST.
Study patients. From March 30, 1993 until July 31, 1995,
1,042 consecutive patients underwent intracoronary stenting at
Centro Cuore Columbus Hospital in Milan, Italy. To analyze
factors associated with SST, we excluded 41 patients: 6 patients
(0.6%) who had acute stent thrombosis within 24 h of the index
procedure, 29 patients (2.8%) who underwent coronary artery
bypass surgery (27 emergently and 2 within the 1st 24 h after
stenting) and 6 patients (0.6%) who died during the procedure.
A total of 1,001 patients with 1,334 lesions were included in
this study. Patients were classified into two groups: 982 patients
(1,315 lesions) without SST and 19 patients (19 lesions) with
Stent implantation procedure. Intracoronary stenting was
performed by using techniques previously described (7–9). The
Palmaz-Schatz coronary stent (Johnson & Johnson Interven-
tional Systems) was the stent most commonly used. Other
From the Lenox Hill Hospital, New York, New York; *Centro Cuore
Columbus, Milan, Italy; and †University of California, Irvine, California.
Manuscript received May 10, 1996; revised manuscript received September
18, 1996, accepted September 25, 1996.
Address for correspondence: Dr. Antonio Colombo, Centro Cuore Colum-
bus, Via M. Buonarotti 48, 20145 Milan, Italy.
JACC Vol. 29, No. 1
?1997 by the American College of Cardiology
Published by Elsevier Science Inc.
retrospective analysis; multiple different designs of stents were
used, a situation that does not allow one to draw conclusions
regarding the role of a specific stent design in inducing
thrombosis; the assignment of antiplatelet regimens was not
based on a randomized protocol, thus limiting conclusions in
regard to the best post-stenting pharmacologic regimen. In
addition, because of the low event rate (SST) in this cohort,
two common problems might arise: Chance occurrences may
suggest significant observations, and true relations may not
achieve nominal significance. Therefore, ideally in the present
era of stent implantation, a larger cohort of patients is neces-
sary to determine predictors of SST with high statistical power.
Despite these limitations, this is the first large study to examine
predictors of SST in the era of high pressure stent deployment
without anticoagulation, and it provides a practical insight into
the multifactorial nature of this process.
Conclusions. SST in this era of stent implantation without
subsequent anticoagulation has diminished. However, despite
aggressive management, it is still associated with serious
clinical events. This study has identified several factors that
predispose to SST: low ejection fraction, intraprocedural com-
plications with postprocedure residual dissections or slow flow
leading to a final suboptimal angiographic or IVUS result.
Other adverse factors that may have a role in SST include
preexisting thrombus and use of multiple stents. The role of
different regimens of antiplatelet therapy, including some new,
more specific antiplatelet agents, needs to be further investi-
gated, particularly in high risk groups. In addition, new stent
designs with a higher rate of successful implantation in com-
plex and unfavorable anatomic settings may further decrease
the number of patients who have a final suboptimal result.
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MOUSSA ET AL.
SUBACUTE STENT THROMBOSIS
JACC Vol. 29, No. 1