WSO - March 2024 - 363

Baik et al.
363
Table 1. Effect of dual-antiplatelet therapy on individual outcomes after stent-assisted coil for unruptured cerebral aneurysm.
Primary composite outcome
(n = 356)
Exposure
period
Index date to
90 days
91-180 days
181-365 days
N aHR (95% CI)
100
45
94
366-730 days 117
Ischemic stroke (n = 229)
p-value N aHR (95% CI)
0.44 (0.28-0.69) <0.001
0.87 (0.47-1.58)
0.97 (0.64-1.46)
0.96 (0.56-1.65)
aHR: adjusted hazard ratio; CI: confidence interval.
Data were obtained from the multivariable time-dependent Cox proportional hazards regression model for the development of the outcome.
Dual-antiplatelet therapy is considered the cornerstone
therapy to avoid in-stent thrombosis, a fatal complication
after stent implantation; the administration of DAPT for a
certain period is therefore considered a mandatory requirement
after stent implantation.4 However, there are no large
randomized control trials and evidence-based guidelines
for the optimal duration of DAPT after SAC for UIA.1,3,5
The optimal duration of DAPT after stent placement is
mainly investigated in patients with coronary artery disease
and differs according to both bleeding and thromboembolic
risks.7-9 Considering that patients with UIA treated with
SAC do not have symptomatic atherosclerotic stenosis, and
all the stents used for UIA are of bare metal, the optimal
duration of DAPT for these patients might be 1-6 months,
as is the recommended period in patients with stable coronary
artery disease who are treated with bare-metal stents.7-9
After the placement of carotid artery stents, DAPT was also
recommended for at least 1-3 months to minimize the risks
of stent thrombosis and ischemic complications.18,19 From
the perspective of stent implantation in cerebral arteries,
previous randomized trials continued DAPT for 1-3 months
in patients allocated stenting, which compared the best
medical management with stent implantation in patients
with symptomatic severe stenotic arteries.20-22
In our analysis of the period after SAC, the risk of primary
composite outcome was significantly reduced by
DAPT only within 3 months after SAC. The benefits and
disadvantages of DAPT were balanced out in this study
beyond 3 months after SAC. Considering existing coronary
guidelines and previous studies, our finding seems plausible.6-9,18-24
A small multi-center randomized trial in 2023
revealed no significant difference in ischemic stroke or
hemorrhagic events within 3-12 months post-SAC between
short-term (3 month) and long-term (12 month) DAPT, suggesting
that the benefits of long-term DAPT after SAC may
be limited.24 However, the study evaluated only 44% of the
planned patients and had a relatively small sample size
(N = 142).24 Two recent reports have also addressed the
optimal duration of DAPT for patients with UIA treated
with SAC. According to a national survey conducted in
French neurointerventional surgery centers, DAPT was
maintained for 3 months in 62% and 6 months in 38% of
centers after SAC for UIA.23 In a multi-center retrospective
study conducted in Japan involving 632 patients with UIA,
it was suggested that the duration of DAPT after SAC or
flow-version procedures could be shortened to 90 days or
less.6 However, it should be noted that only univariable
Cox regression analysis was performed in this study due to
the limited number of events.6
In this study, DAPT was independently associated with a
reduced risk of ischemic stroke not only within 3 months but
also 3-6 months after SAC. There was no difference in the
risk of ischemic stroke according to DAPT over 6 months
after SAC. This time-varying dynamic change in the protective
effect of DAPT is consistent with the findings of previous
studies on patients with coronary artery stents. Serial
angioscopic observation after bare-metal stent implantation
in patients with coronary artery disease showed that completing
neointimal coverage reduced the risk of stent thrombosis
and only required approximately 3 months.12 The
relationship between stent thrombosis and discontinuation
of DAPT remains important until 6 months after stent
implantation but fades thereafter.13 Although our study
showed the beneficial effect of DAPT between 3-6 months,
it was attenuated because of increased hemorrhage risk, and
finally, the risk of primary composite outcome showed no
difference according to DAPT in 3-6 months after SAC.
Consistent with our results, a previous randomized trial suggested
that in patients with coronary artery disease, using
either bare-metal or drug-eluting stents, a DAPT duration of
24 months showed no benefit for reduced risk of death,
myocardial infarction, or stent thrombosis but showed an
increased hemorrhage risk compared to those with a
6-month DAPT duration.25 Based on our results, DAPT for
3-6 months after SAC may be considered only in selected
patients at high risk of thromboembolic complications.
International Journal of Stroke, 19(3)
0.643
0.873
0.879
Major bleeding (n = 127)
59 0.31 (0.18-0.54) <0.001 41
26 0.40 (0.18-0.88)
60 0.61 (0.35-1.07)
84 0.58 (0.27-1.27)
0.022 19
0.086 34
0.174 33
p-value N aHR (95% CI)
0.83 (0.36-1.90)
4.34 (1.00-18.85)
2.06 (1.05-4.03)
2.17 (0.97-4.86)
p-value
0.656
0.050
0.035
0.061
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