Neurol Med Chir (Tokyo) 54, 46–53, 2014
doi: 10.2176/nmc.oa.2013-0319 Online December 20, 2013
Special Theme Topic: Japanese Surveillance of Neuroendovascular Therapy in JR-NET/JR-NET2—Part I
Angioplasty and Stenting for Intracranial Stenosis Takashi Izumi,1 Hirotoshi Imamura,2 Nobuyuki Sakai,2 and Shigeru Miyachi1 Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi; 2 Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Hyogo 1
Abstract Of the patients enrolled in the Japanese Registry of Neuroendovascular Therapy (JR-NET), a surveillance study in Japanese, 1133 patients who underwent intracranial percutaneous transluminal angioplasty (PTA)/stenting for intracranial stenosis during the period from 2005 to 2009 were investigated. A technical success was achieved in 98.3% of the patients, and 70.5% and 7.5% had a residual stenosis of < 30% and ≥ 50%, respectively. The incidence of ischemic complications and hemorrhagic complications was as low as 7.7% and 2.5%, respectively, but tended to increase in patients who underwent stenting. While a significant correlation with ischemic complications was observed in previously untreated patients and patients who underwent stenting followed by post-dilatation, a significant correlation with hemorrhagic complications was observed in patients who received emergency treatment and those treated between 24 hours and 14 days of the onset. Flexible intracranial stents are expected to contribute to improvement in the treatment outcome. Key words: intracranial stenosis, angioplasty, stenting
Introduction
development of endovascular therapy for intracranial stenosis. The Japanese Registry of Neuroendovascular Therapy (JR-NET) was a retrospective registration survey on all neuroendovascular procedures performed in Japan. Procedures performed from 2005 to 2006 were included in JR-NET1, and those from 2007 to 2009 were included in JR-NET2. We report the results of the JR-NET, including analysis and discussion.
Angioplasty has traditionally been used for the treatment of intracranial stenosis, primarily for intracranial stenosis refractory to medical therapy. However, since no stent is specifically designed for intracranial arteries, treatment is usually completed with balloon angioplasty alone, and stenting using a coronary stent is applied only in unavoidable circumstances. While more flexible intracranial stents that are compatible with the characteristics of more tortuous intracranial arteries have been awaited for a long time, the Wingspan (Stryker, Kalamazoo, Michigan, USA) was approved in the United States in 2005, and an investigator-initiated clinical trial is under way in Japan with the aim of gaining coverage by the Japanese National Health Insurance system. In advance of introduction of intracranial stents in Japan, review of previous treatment results in Japan may be essential for the
Materials All patients enrolled in JR-NET1 or JR-NET2 who were treated with intracranial percutaneous transluminal angioplasty (PTA)/stenting for intracranial stenosis were included in the present study. Data from a total of 1133 patients who underwent angioplasty/ stenting for intracranial stenosis were analyzed: 438 patients in JR-NET1 (2005 to 2006) and 695 patients in JR-NET2 (2007 to 2009).
Received September 30, 2013; Accepted November 22, 2013
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Methods
Results
Data files from JR-NET were used to determine correlations between differences in the baseline characteristics of patients, procedures, or perioperative management, and the occurrence of hemorrhagic or ischemic complications in a retrospective manner. Data were analyzed for each factor, except for “unknown” data and missing data. For the factors asked about in JR-NET2 but not in JR-NET1 (presence or absence of pre-dilatation and postdilatation, type of stent, timing of treatment, and presence or absence ofgeneral anesthesia), only data from JR-NET2 were used. Statistical analysis was performed by chi-square test using excel statistics.
The baseline characteristics of patients, lesion profile, treatment situation, treatment, treatment outcome, and complications are shown in Table 1. The mean age was 66.7 (19 to 94) years, and the proportion of male subjects was as high as 76.5%. At baseline, the mean modified Rankin scale (mRS) was 0.86, and patients with an mRS of 0 to 2 accounted for 89.1%. Of all patients, 25.0% received treatment under general anesthesia, and 17.0% received emergency treatment. Stenting was performed in 60.6% patients. The most common preoperative antiplatelet treatment was treatment with two agents in 71.6%, followed by treatment with one agent in 14.1%. While the most common postoperative antithrombotic agents
Table 1 Characteristics of 1,133 patients Patient characteristics Baseline characteristics of patients
Lesion profile
Treatment situation
Age
Mean 66.8 (19–94) years
Sex
Male 76.5%
mRS at baseline
Mean 0.86
mRS 0 to 2
89.1%
Previously untreated
92.7%
Region
IC (intracranial epidural): 36.0%, IC (intradural): 84.7%, MCA: 22.2%, VA: 16.6%, BA: 14.4%, other: 2.4%
Symptom at diagnosis
Asymptomatic: 19.9%, amaurosis: 1.4%, TIA (cerebrum): 22.1%, minor stroke: 36.5%, major stroke: 8.7%, progressing: 11.3%
Timing of treatment (JR-NET2)
Within 24 hr: 13.5%, within 14 days: 20%, after at least 15 days: 66.5%
Percent diameter stenosis
< 50%: 2.4%, 50% to 60%: 4.5%, 60% to 70%: 9.9%, 70% to 80%: 32.0%, 80% to 90%: 26.7%, 90% to 100%: 22.2%, 100%: 2.3%
Lesion length
< 5 mm: 25.0%, 5–10 mm: 53.2%, 10–15 mm: 16.3%, ≥ 15 mm: 5.5%
Normal vascular diameter
< 2 mm: 1.9%, 2–2.5 mm: 16.0%, 2.5–3 mm: 24.1%, 3–3.5 mm: 25.1%, 3.5–4 mm: 19.7%, ≥ 4 mm: 13.2%
Pathology
Arteriosclerosis: 93%, traumatic dissection 0.3%, iatrogenic dissection 0.7%, idiopathic dissection 1.1%, others 4.7%
Refractory to medical therapy
44.9%
Diagnostic cerebral angiography
39.6%
Emergency treatment
17.0%
Treatment at another hospital
10.6%
Investigator
Supervisory physician: 55.0%, specialist: 37.4%, nonspecialist: 7.5%
Scrub-in of supervisory physician
62.5%
No. of scrub-in supervisory physicians and specialists
1: 58.0%, 2: 33.0%, ≥ 3: 9.0%
General anesthesia (JR-NET2)
25.0% (Continued)
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Table 1 (Continued) Treatment
Treatment outcome
Stenting
Yes: 60.6%
Presence or absence of pre-dilatation (JR-NET2)
Yes: 72.0%
Use of coronary stent (JR-NET2)
97.9%
Presence or absence of post-dilatation (JR-NET2)
28.8%
Preoperative antiplatelet treatment
No: 5.4%, 1 agent: 14.1%, 2 agents: 71.6%, 3 agents: 8.9%
Postoperative antiplatelet treatment
No: 6.0%, 1 agent: 12.7%, 2 agents: 71.7%, 3 agents: 9.6%
Postoperative antithrombotic treatment
No: 26.4%, heparin: 25.9%, argatroban: 38.9%, ozagrel: 3.1%, combination: 5.6%
Other concurrent treatment
12.8%
Technical success
98.3%
Residual stenosis immediately after treatment
< 30%: 70.5%, 30% to 50%: 22.1%, ≥ 50%: 7.5%
Hemorrhagic complication
2.5%
Ischemic complication
7.7%
mRS at 30 days postoperatively
Mean 1.02
Postoperative increase in mRS ≥ 2 points
8.6%
Mortality
1.9%
BA: basilar artery, IC: internal cerebral artery, JR-NET: Japanese Registry of Neuroendovascular Therapy, MCA: middle cerebral artery, mRS: modified Rankin scale, TIA: transient ischemic attack, VA: vertebral artery.
Table 2 Details of ischemic complications and hemorrhagic complications Total
Incidence(%)
Distal embolization
39
3.4
Vascular dissection
21
1.9
Acute obstruction
15
1.3
Ischemic complication
Other
4
0.4
Unknown
8
0.8
Total
87
7.7
Hemorrhagic complication Vascular rupture
7
0.6
Hyperperfusion
5
0.4
Vascular dissection
3
0.3
Vessel perforation
2
0.2
Other
5
0.4
Unknown
6
0.5
Total
28
2.5
were argatroban in 38.9% and heparin in 25.9%, no postoperative antithrombotic treatment was performed in 26.4%. Technical success was achieved in 98.3%,
and 70.5% and 7.5% had a residual stenosis of < 30% and ≥ 50%, respectively. The incidence of ischemic complications and hemorrhagic complications was 7.7% (87 patients) and 2.5% (28 patients), respectively, and 1 patient had both ischemic and hemorrhagic complications. As a result, the incidence of hemorrhagic and ischemic complications within 30 days postoperatively was 10.1%. At 30 days postoperatively, the mean mRS was 1.02, and the mRS increased from baseline by 2 points or more in 8.6%. The mortality was 1.9%. Ischemic and hemorrhagic complications are listed in Table 2. The most common ischemic complication was distal embolization in 3.4%, followed by vascular dissection in 1.9%. The most common hemorrhagic complications were vascular rupture in 0.6% and hyperperfusion-related hemorrhage in 0.4% of patients. Correlation between each factor tested and ischemic complications are shown in Table 3. The following factors were significantly correlated with ischemic complications: no previous treatment; not refractory to medical therapy; stenting followed by postdilatation; postoperative antithrombotic treatment; and supervisory physician who served as the investigator. The incidence of ischemic complications was significantly lower in patients who received
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Table 3 Correlation between each factor and ischemic complications Baseline characteristics of patients
Lesion profile
Age
≤ 49 years: 7.0%, 50 to 59 years: 6.9%, 60 to 69 years: 7.1%, 70 to 79 years: 6.7%, ≥ 80 years: 2.7%
Sex
Male: 6.6%, female: 6.6%
mRS at baseline
0 to 2: 6.9%, 3 to 5: 5.2%
Previous treatment
Previously untreated: 8.4%, previously treated: 2.2% (p < 0.05)
Region
IC (intracranial epidural): 6.2%, IC (intradural): 5.5%, MCA: 7.5%, VA: 9.6%, BA: 11.0%
Symptom at diagnosis
Asymptomatic: 8.0%, symptomatic: 7.8% Nonprogressively symptomatic: 8.1%, progressively symptomatic: 5.8%
Treatment
Treatment situation
Treatment outcome
Timing of treatment (only symptomatic patients)
Within 24 hr: 8.8%, between 24 hr and 14 days: 5.9%, after at least 15 days: 7.7%
Percent diameter stenosis
< 50%: 8.0%, 50% to 60%: 8.7%, 60% to 70%: 8.9%, 70% to 80%: 7.3%, 80% to 90%: 7.3%, 90% to 100%: 8.4%, 100%: 8.7%
Lesion length
< 5 mm: 8.3%, 5–10 mm: 6.4%, 10–15 mm: 12.2%, ≥ 15 mm: 5.4%
Normal vascular diameter
< 2 mm: 0%, 2–2.5 mm: 10.4%, 2.5–3 mm: 10.2%, 3–3.5 mm: 5.9%, 3.5–4 mm: 6.5%, ≥ 4 mm: 6.7%
Pathology
Arteriosclerosis: 7.2%, traumatic dissection 0%, iatrogenic dissection 0%, idiopathic dissection 12.5%, others 3.1%
Refractory to medical therapy
No: 8.8%, yes: 5.0% (p < 0.05)
Stenting
No: 6.6%, yes: 9.7%
Presence or absence of pre-dilatation (JR-NET2)
No: 10.1%, yes: 6.0%
Presence or absence of post-dilatation (JR-NET2)
No: 5.7%, yes: 9.8%
Stent + presence or absence of post-dilatation (JR-NET2)
No: 5.6%, yes: 14.0% (p < 0.05)
Preoperative antiplatelet treatment
No: 8.9%, 1 agent: 6.2%, 2 agents: 8.2%, 3 agents: 7.6%
Postoperative antiplatelet treatment
No: 11.2%, 1 agent: 8.3%, 2 agents: 7.0%, 3 agents: 12.0%
Postoperative antithrombotic treatment
No: 4.9%, heparin: 3.5%, argatroban: 9.7%, ozagrel: 12.9%, combination: 30.3% (p < 0.000000001*)
Other concurrent treatment
No: 7.3%, yes: 11.0%
Diagnostic cerebral angiography
No: 8.0%, yes: 7.4%
Emergency treatment
Planned: 7.2%, emergency: 10.4%
Treatment facility
Hospital at work: 8.2%, another hospital: 3.3%
Investigator
Supervisory physician: 10.1%, specialist: 4.5%, nonspecialist: 5.8% (p < 0.01**)
Scrub-in of supervisory physician
No: 2.7%, yes: 10.0% (p < 0.001)
No. of scrub-in supervisory physicians and specialists
1: 7.1%, 2: 8.8%, ≥ 3: 3.3%
General anesthesia
Local anesthesia: 7.7%, general anesthesia: 5.7%
Residual stenosis immediately after treatment
< 30%: 7.4%, 30% to 50%: 7.0%, ≥ 50%: 11.7%
*: Each p-value is shown in Table 4. **: Supervisory physician vs. specialist (p < 0.001). mRS: modified Rankin scale.
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Table 4 Correlation between postoperative antithrombotic treatment and ischemic complications Ischemic Ischemic complication (–) complication (+)
Total
Incidence
p value
No postoperative antithrombotic treatment
253
13
266
4.9%
p < 0.000000001
n.s.
p < 0.05 p < 0.01
Heparin
251
9
260
3.5%
p < 0.00000001
n.s.
p < 0.05 *
Argatroban
353
38
391
9.7%
p < 0.001
n.s.
Ozagrel
27
4
31
12.9%
n.s.
*
Combination
39
17
56
30.3%
*
*
*: control. n.s.: no significant.
Table 5 Correlation between each factor and hemorrhagic complications Baseline characteristics of patients
Lesion profile
Age
≤ 49 yrs: 4.2%, 50–59 yrs: 2.8%, 60–69 yrs: 1.6%, 70–79 yrs: 2.2%, ≥ 80 yrs: 4.1%
Sex
Male: 2.1%, female: 3.1%
mRS at baseline
0% to 2: 2.2%, 3% to 5: 3.2%
Previous treatment
Previously untreated: 2.8%, previously treated: 2.2%
Region
IC (intracranial epidural): 1.8%, IC (intradural): 4.4%, MCA: 2.5%, VA: 3.4%, BA: 4.0%
Symptom at diagnosis
Asymptomatic: 1.9%, symptomatic: 2.9% Nonprogressively symptomatic: 2.2%, progressively symptomatic: 6.6% (p < 0.05)
Treatment
Timing of treatment (only symptomatic patients)
Within 24 hr: 2.9%, between 24 hr and 14 days: 5.9%, after at least 15 days: 1.5% (p < 0.05*)
Percent diameter stenosis
< 50%: 0%, 50% to 60%: 0%, 60% to 70%: 3.0%, 70% to 80%: 1.5%, 80% to 90%: 4.0%, 90% to 100%: 3.5%, 100%: 0%
Lesion length
< 5 mm: 1.6%, 5–10 mm: 3.0%, 10–15 mm: 3.0%, ≥ 15 mm: 3.6%
Normal vascular diameter
< 2 mm: 4.8%, 2–2.5 mm: 1.8%, 2.5–3 mm: 2.0%, 3–3.5 mm: 2.3%, 3.5–4 mm: 3.0%, ≥ 4 mm: 5.2%
Pathology
Arteriosclerosis: 1.9%, traumatic dissection 0%, iatrogenic dissection 20%, idiopathic dissection 0%, others 0%
Refractory to medical therapy
No: 2.7%, yes: 2.5%
Stenting
No: 2.4%, yes: 3.2%
Presence or absence of pre-dilatation (JR-NET2)
No: 1.6%, yes: 2.5%
Presence or absence of post-dilatation (JR-NET2)
No: 2.3%, yes: 2.1%
Stent + presence or absence of post-dilatation (JR-NET2)
No: 3.7%, yes: 5.0%
Preoperative antiplatelet treatment
No: 5.4%, 1 agent: 4.8%, 2 agents: 2.0%, 3 agents: 3.2%
Postoperative antiplatelet treatment
No: 10.0%, 1 agent: 6.0%, 2 agents: 1.3%, 3 agents: 1.0% (p < 0.000000001**)
Postoperative antithrombotic treatment
No: 7.1%, heparin: 1.9%, argatroban: 0.8%, ozagrel: 0%, combination: 1.8% (p < 0.0001***) (Continued)
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Table 5 (Continued) Treatment situation
Treatment outcome
Other concurrent treatment
No: 3.0%, yes: 0.7%
Diagnostic cerebral angiography
No: 3.1%, yes: 2.2%
Emergency treatment
Planned: 2.1%, emergency: 5.7% (p < 0.01)
Treatment facility
Hospital at work: 2.7%, another hospital: 3.3%
Investigator
Supervisory physician: 3.4%, specialist: 2.4%, nonspecialist: 0%
Scrub-in of supervisory physician
No: 2.3%, yes: 2.1%
No. of scrub-in supervisory physicians and specialists
1: 2.0%, 2: 3.1%, ≥ 3: 0.0%
General anesthesia
Local anesthesia: 1.7%, general anesthesia: 4.0%
Residual stenosis immediately after treatment
< 30%: 2.6%, 30% to 50%: 3.1%, ≥ 50%: 0%
*: Within 24 hr vs. between 24 hr and 14 days: p < 0.05. **: Each p-value is not shown. ***: Each p-value is not shown. JRNET: Japanese Registry of Neuroendovascular Therapy.
Table 6 Correlation between complications and mortality Mortality No
Yes
Hemorrhagic complication
1.3%
23.3%
(p < 0.0000001)
Ischemic complication
1.8%
2.3%
n.s.
n.s.: no significant.
postoperative antithrombotic treatment with heparin alone than in those who received no postoperative antithrombotic treatment (Table 4). Correlation between each factor tested and hemorrhagic complications are shown in Table 5. The following factors were significantly correlated with hemorrhagic complications: progressively symptomatic; treatment between 24 hours and 14 days of the onset; no postoperative antiplatelet treatment; no postoperative antithrombotic treatment; and emergency treatment. In patients with hemorrhagic complications, the mortality was very high at 23.3% (Table 6).
Discussion In this study, the incidence of ischemic complications and hemorrhagic complications was 7.7% and 2.5% in 1,133 patients who underwent angioplasty/stenting, respectively, resulting in an overall incidence of approximately 10%. Nguyen et al. reported that of 74 patients, 5% of patients who underwent angioplasty for symptomatic intracranial stenosis experienced major stroke within 30 days postoperatively.1) In the
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present study, the incidence of ischemic complications and hemorrhagic complications was 6.6% and 2.4%, respectively, in patients who underwent PTA alone. The higher incidence of complications in this study may be because the complications included minor stroke, unlike in Nguyen’s study. When limited to patients who underwent stenting, on the other hand, the incidence of ischemic complications and hemorrhagic complications was relatively high at 9.7% and 3.2%, respectively, in Japan. This outcome was worse compared even with a 30-day stroke rate of 5.7% reported with Wingspan, an intracranial stent approved in the United States, at the time of approval.2) This may have been due to the use of inflexible coronary stents in the present study, which was more likely to result in vascular injury at the time of access or stent deployment. In addition, since the incidence of complications was greatly different with or without stenting in this study, it is likely that there may have been problems with the device. On the other hand, the proportion of patients who had a residual stenosis of ≥ 50% postoperatively was significantly lower in the stenting group, showing the usefulness of stenting in maintaining cerebral artery patency and thus warranting quick approval of flexible intracranial stents. In this study, which had a large sample size (1,133 patients), several factors were found to be correlated with complications, and even multifactorial analysis could have been performed. However, since the data were retrospectively collected and analyzed, it is not doubtful that various biases existed. For instance, hemorrhagic complications may substantially restrict subsequent antithrombotic therapy. For significantly
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biased data, it may be more important to analyze individual factors correlated with complications carefully, rather than to perform a multifactorial analysis. In the analysis, first, several factors were correlated with ischemic complications. The incidence of complications was significantly lower in previously treated patients. Patients who experienced complications at the initial treatment often preclude retreatment for medical or social reasons, thus more patients who experienced no complications at the initial treatment might have been included in the previously treated group. In many previously treated patients, angioplasty may have been more suitable in terms of plaque characteristics or position of penetrating branches in the lesion. In addition, the intima formed after the initial treatment may have been histopathologically stable. In this study, an unexpected negative correlation was observed in patients unresponsive to medical therapy, although such patients generally have an increased risk of ischemic complications. Many of the patients enrolled with the disease refractory to medical therapy may have received not only adequate antiplatelet treatment, but also medical therapy such as statins or intensive antidiabetic treatment that can contribute to plaque stabilization. It may be hypothesized that medical therapy contributing to plaque stabilization reduced ischemic complications and is thus useful in enhancing the safety of angioplasty although this is a matter of speculation since non-antithrombotic drugs were not investigated. Additional post-dilatation following placement of balloon-expandable coronary stent was also significantly correlated with ischemic complications. Plaques excluded by repeated PTA may have impaired blood flow in the penetrating branches. As for postoperative antithrombotic therapy, the incidence of ischemic complications was significantly lower in heparin-treated patients than in untreated patients, indicating the usefulness of heparin. On the other hand, treatment with multiple antithrombotics was also positively correlated with ischemic complications. This may be because ischemic complications occurred in many of the patients who received multiple antithrombotics for the treatment of intraoperative ischemic symptoms. In addition, some factors were found to be correlated with hemorrhagic complications. Progressively symptomatic disease, which is complicated by so-called misery perfusion, may have resulted in cerebral hemorrhage due to hyperperfusion syndrome. The higher incidence of hemorrhagic complications in patients treated between 24 hours and 14 days of the onset may be explained by the assumption that hemorrhagic changes were caused by reperfusion
of brain tissue that had just undergone irreversible ischemic changes, although there was no data on cerebral blood flow, such as single photon emission computed tomography (SPECT) or positron emission tomography (PET), in our study. Likewise, postoperative hemorrhagic complications were more likely to occur in patients who received emergency treatment, because such patients often develop acute cerebral infarction. In addition, inadequate preoperative assessment or equipment may have resulted in vascular injury during catheter manipulation or PTA in patients who received emergency treatment. A positive correlation with hemorrhagic complications was observed in patients who received no postoperative antiplatelet or antithrombotic treatment, but this may be explained by the fact that hemorrhagic complications precluded the use of these drugs. As mentioned above, the data were retrospectively collected and analyzed in this study, requiring prospective confirmatory studies to determine whether each factor found to be correlated with complications is actually a risk factor for complications. This procedure is associated with more complications than other neuroendovascular procedures, and unfortunately the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial, a randomized controlled study in the United States, failed to show the effectiveness of stenting and abandoned.3) The final result of this study also showed that the early benefit of aggressive medical management over aggressive medical management plus stenting with the Wingspan stent persists during a median follow-up of 32.4 months.4) It may be important to not only use intracranial stents, which are expected to be introduced in Japan in the near future, but also to seek to improve the treatment outcome in a multidimensional manner based on the findings of the present study.
Conclusion Angioplasty for intracranial stenosis in Japan is almost as safe as that in the West. On the other hand, stenting using a coronary stent is associated with a higher incidence of complications, warranting quick introduction of intracranial stents.
Acknowledgments This study was supported by research grants for cardiovascular diseases (17C-1, 20C-2) from the Ministry of Health, Labor, and Welfare of Japan. The authors would like to express their heartfelt thanks to doctors who devoted their time to this
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investigation. The JR-NET Study Group: Principle investigator; Nobuyuki Sakai, Kobe City Medical Center General Hospital, Kobe, Japan: Investigators; Akio Hyodo, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Japan (17C-1, 20C-2), Shigeru Miyachi, Nagoya University, Nagoya, Japan (17C-1, 20C-2), Yoji Nagai, Translational Research Informatics Center, Kobe, Japan (17C-1, 20C-2), Chiaki Sakai, Institute of Biomedical Research and Innovation, Kobe, Japan (17C-1, 20C-2), Tetsu Satow, National Cerebral and Cardiovascular Center, Suita, Japan (17C-1, 20C-2). Waro Taki, Mie University, Tsu, Japan (17C-1, 20C-2), Tomoaki Terada, Wakayama Rosai Hospital, Wakayama, Japan (17C-1, 20C-2), Masayuki Ezura, Sendai Medical Center, Sendai, Japan (17C-1). Toshio Hyogo, Nakamura Memorial Hospital, Sapporo, Japan (17C-1), Shunji Matsubara, Tokushima University, Tokushima, Japan (17C-1), Kentaro Hayashi, Nagasaki University, Nagasaki Japan (20C-2); Co-investigators; Toshiyuki Fujinaka, Osaka University, Suita, Japan, Yasushi Ito, Niigata University, Niigata, Japan, Shigeki Kobayashi, Chiba Emergency Medical Center, Chiba, Japan, Masaki Komiyama, Osaka City General Hospital, Osaka, Japan, Naoya Kuwayama, Toyama University, Toyama, Japan, Yuji Matsumaru, Toranomon Hospital, Japan, Yasushi Matsumoto, Konan Hospital, Sendai, Japan, Yuichi Murayama, Jikei Medical University, Tokyo, Japan, Ichiro Nakahara, Kokura Memorial Hospital, Kokura, Japan, Shigeru Nemoto, Jichi Medical University, Shimotsuke, Japan, Koichi Sato, Tokushima Red Cross Hospital, Tokushima, Japan, Kenji Sugiu, Okayama University, Okayama, Japan, Shinichi Yoshimura, Gifu University, Gifu, Japan, and certified specialist of Japanese Society of Neuroendovascular Therapy.
Conflicts of Interest Disclosure All authors who are members of The Japan Neurosurgical Society (JNS) have registered self-reported
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COI disclosure statements through the website for JNS members.
References 1) Nguyen TN, Zaidat OO, Gupta R, Nogueira RG, Tariq N, Kalia JS, Norbash AM, Qureshi AI: Balloon angioplasty for intracranial atherosclerotic disease: periprocedural risks and short-term outcomes in a multicenter study. Stroke 42: 107–111, 2011 2) Fiorella DJ, Turk AS, Levy EI, Pride GL, Woo HH, Albuquerque FC, Welch BG, Niemann DB, AagaardKienitz B, Rasmussen PA, Hopkins LN, Masaryk TJ, McDougall CG: U.S. Wingspan Registry: 12-month follow-up results. Stroke 42: 1976–1981, 2011 3) Chimowitz MI, Lynn MJ, Derdeyn CP, Turan TN, Fiorella D, Lane BF, Janis LS, Lutsep HL, Barnwell SL, Waters MF, Hoh BL, Hourihane JM, Levy EI, Alexandrov AV, Harrigan MR, Chiu D, Klucznik RP, Clark JM, McDougall CG, Johnson MD, Pride GL, Torbey MT, Zaidat OO, Rumboldt Z, Cloft HJ; SAMMPRIS Trial Investigators: Stenting versus aggressive medical therapy for intracranial arterial stenosis. N Engl J Med 365: 993–1003, 2011 4) Derdeyn CP, Chimowitz MI, Lynn MJ, Fiorella D, Turan TN, Janis LS, Montgomery J, Nizam A, Lane BF, Lutsep HL, Barnwell SL, Waters MF, Hoh BL, Hourihane JM, Levy EI, Alexandrov AV, Harrigan MR, Chiu D, Klucznik RP, Clark JM, McDougall CG, Johnson MD, Pride GL Jr, Lynch JR, Zaidat OO, Rumboldt Z, Cloft HJ; for the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis Trial Investigators: Aggressive medical treatment with or without stenting in high-risk patients with intracranial artery stenosis (SAMMPRIS): the final results of a randomised trial. Lancet, Epub 2013 Oct 25
Address reprint requests to: Takashi Izumi, MD, Department of Neurosurgery, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466–8550, Japan. e-mail:
[email protected]