INTERVENTIONAL NEURORADIOLOGY
VOLUME 21 - No. 4 august 2015 ISSN 1591-0199 Online ISSN 2385-2011
Volume 21, No. 4, Pages 421 - 560, 2015
Journal of Peritherapeutic Neuroradiology, Surgical Procedures and Related Neurosciences Official Journal of: WFITN - World Federation of Interventional and Therapeutic Neuroradiology AAFITN - Asian & Australasian Federation of Interventional & Therapeutic Neuroradiology SAWITN - South American Working Group in Interventional and Therapeutic Neuroradiology The Chinese INR Coordinating Committee of the Chinese Doctor Association INSHCM - Interventional Neuroradiology Society of HCM City, Viet Nam Journal sponsored by JSNET - Japanese Society of Neuro Endovascular Therapy FIO - Italian Federation of Ozone Therapy Interventional Neuroradiology is published in cooperation with the American Journal of Neuroradiology
Original Article
Percutaneous transluminal angioplasty and stenting for severe stenosis of the intracranial extradural internal carotid artery causing transient ischemic attack or minor stroke
Interventional Neuroradiology 2015, Vol. 21(4) 511–519 ! The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1591019915582379 ine.sagepub.com
Jun Kyeung Ko1, Chang Hwa Choi1, Seung Heon Cha1, Byung Kwan Choi1, Won Ho Cho1, Tae Ho Kang2, Sang Min Sung2, Han Jin Cho2 and Tae Hong Lee3
Abstract The purpose of this study is to assess the technical feasibility and clinical efficacy of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic stenosis of the intracranial extradural (petrous and cavernous) internal carotid artery (ICA). Review of medical records identified 26 consecutive patients who underwent PTAS using a balloon-expandable coronary stent (n ¼ 15, 57.7%) or a Wingspan self-expandable stent (n ¼ 11, 42.3%) for treatment of severe stenosis (>70%) involving the intracranial extradural ICA. The inclusion criteria were transient ischemic attack with an ABCD2 score of 3 (n ¼ 12, 46.2%) or minor stroke with an NIHSS score of 4 (n ¼ 14, 53.8%). Technical success rates, complications, and angiographic and clinical outcomes were analyzed retrospectively. PTAS was technically successful in all patients. The mean stenosis ratio decreased from 77.1% to 10.0% immediately after PTAS. The overall incidence of procedural complications was 23.1%, and the postoperative permanent morbidity/mortality rate was 7.7%. A total of 22 patients were tracked over an average period of 29.9 months. During the observation period, 20 patients (90.9%) had no further cerebrovascular events and stroke recurrence occurred in two patients (9.1%), resulting in an annual stroke risk of 3.7%. Two cases (11.1%) of significant in-stent restenosis (>50%) were found on follow-up angiography (n ¼ 18). PTAS for severe stenosis (>70%) involving the intracranial extradural ICA showed a good technical feasibility and favorable clinical outcome in patients with transient ischemic attack or minor stroke.
Keywords Stents, angioplasty, carotid stenosis, transient ischemic attack, stroke
Introduction The Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) trial was designed to assess whether percutaneous transluminal angioplasty and stenting (PTAS) plus aggressive medical treatment is more effective than aggressive medical treatment alone in patients with recent transient ischemic attack (TIA) or stroke (within the past 30 days) attributed to 70–99% atherosclerotic intracranial arterial stenosis.1 Enrollment in SAMMPRIS began November 25, 2008, but was stopped for safety concerns April 5, 2011, because the 30-day rate of stroke and death was higher in the PTAS group.2 According to the recently reported final results of SAMMPRIS, the early benefit of aggressive medical treatment compared with PTAS
in high-risk patients with intracranial arterial stenosis persisted over a median duration of 32.4 months of follow-up in this trial.3 So far the results of intracranial stenting for this lesion have been very disappointing.
1
Department of Neurosurgery, Medical Research Institute, Pusan National University Hospital, Korea 2 Department of Neurology, Medical Research Institute, Pusan National University Hospital, Korea 3 Department of Diagnostic Radiology, Medical Research Institute, Pusan National University Hospital, Korea Corresponding author: Tae Hong Lee, Department of Diagnostic Radiology, Pusan National University Hospital, 305 Gudeok-Ro, Seo-Gu, Busan, 602-739, Republic of Korea. Email: [email protected]
512 Despite the discouraging final results of SAMMPRIS, there are still subgroups of patients at high risk of stroke on aggressive medical treatment. Several publications report promising outcomes in a subset of patients with severe intracranial arterial stenosis, rendering the efficacy of PTAS contentious.4–8 At this point, we thought that the subgroup analysis according to the lesion location should be performed in order to improve the clinical outcome of intracranial stenting, and noticed the intracranial extradural (petrous and cavernous) segment of the internal carotid artery (ICA). The aim of this study was to assess the technical feasibility and clinical efficacy of PTAS for severe stenosis (>70%) of the intracranial extradural ICA in TIA or minor stroke patients.
Materials and methods Patient population and inclusion criteria A total of 77 symptomatic patients with severe stenosis of the intracranial artery underwent PTAS at our institution between 2006 and 2013. The lesions consisted of 29 distal ICAs, 25 middle cerebral arteries, 16 vertebral arteries, and seven basilar arteries. Among these patients, 26 consecutive patients with stenosis involving the cavernous or petrous portion of the ICA were reviewed retrospectively. Owing to the retrospective nature, the present study is exempt in accord with the institutional review board standards of our institution. The inclusion criteria were TIA with an ABCD2 score of 3 or minor stroke with ICA stenosis of >70%. All patients were evaluated by experienced neurologists and were determined to have clinical symptoms attributable to ICA stenosis. All patients underwent screening with brain magnetic resonance imaging (MRI) and computed tomography (CT) in order to exclude other intracranial diseases, such as hemorrhage or tumors. TIA was defined as an acute transient focal neurological deficit caused by vascular disease that completely reversed within 24 hours and caused no acute lesion on diffusion-weighted imaging (DWI).9 In TIA patients, ABCD2 scoring was performed by assigning points as follows: age (60 years, one point); blood pressure (BP) at first assessment after symptom onset (systolic BP of 140 mm Hg or diastolic BP of 90 mm Hg, one point); clinical features of TIA (unilateral weakness, two points; speech impairment without weakness, one point); duration of symptoms (60 minutes, two points; 10–59 minutes, one point); diabetes (one point).10 Minor stroke was defined as any acute neurological deficit with a new lesion by DWI and a United States National Institutes of Health Stroke Scale (NIHSS) score of 4. All patients underwent digital subtraction angiography before PTAS. Stenosis percentages were calculated by measuring the narrowest vessel diameter visualized within stenosis and expressing this as a ratio of its proximal diameter.11
Interventional Neuroradiology 21(4)
Endovascular procedure All patients received dual antiplatelet medication including 75 mg of clopidogrel and 100 mg of aspirin each day over five days or a loading dose of 300 mg of clopidogrel and 300 mg of aspirin at least 12 hours before endovascular treatment. Interventional procedures were performed in the neuroangiography room, which is equipped with a digital subtraction angiography system (Axiom Artis, Siemens, Germany). All angiographic procedures were performed using a transfemoral approach under local anesthesia using an electrocardiogram, arterial oxygen saturation, and BP monitoring. Prior to the therapeutic procedure, patients were administered a systemic heparinization and a bolus injection of heparin 3000 IU. An additional 1000 IU bolus of heparin was administered every hour in order to maintain an activated coagulation time (ACT) of >200 seconds throughout the procedure. Coaxial catheter-flushing fluid was mixed with heparin at a concentration of 1000 IU of heparin per 1000 ml of saline. Up until April 2010, a balloon-expandable coronary stent (BES) was the only stent available in our institute. Wingspan self-expandable intracranial stent (WS) then became available, and could be used only during the remainder of the study period because of public health insurance regulation. A 6 F guiding catheter (Envoy; Cordis Corporation, USA) was positioned in the distal cervical ICA, and preprocedural angiograms were then obtained in biplanes. The stenotic segment was crossed with a 205 cm long for BES or a 300 cm long for WS, 0.014 inch thick microwire (Transcend 14; Target/Boston Scientific, Natick, MA, USA) placed in the insular portion of the middle cerebral artery to ensure maximal support.
BES Angioplasty and stenting were performed simultaneously using a BES in all patients. The diameter and length of each device were chosen according to the diameter of the normal vessel and the extension of the stenosis. The balloon was slowly inflated using a multistage technique to prevent vessel dissection or rupture. When no gap was present between the stent and the parent artery, deployment was terminated, followed by a 30-minute wait to identify possible complications, such as acute in-stent thrombosis or previously undetected vascular rupture.
WS Before stent deployment, predilation was performed with a Gateway balloon (Boston Scientific Corporation, USA), which was slowly inflated to 80% of the diameter of the reference vessel. A slightly oversized (0.5–1.0 mm) stent was used to enable complete apposition to the vessel wall. The appropriate length was chosen in a way that would ensure coverage
Ko et al. of the stenotic lesion at least 3 mm beyond its proximal and distal extremities. A WS delivery catheter was advanced across the lesion using the road map, and the stent was slowly deployed. If a significant residual stenosis was found on post-stenting angiography, in-stent balloon angioplasty using a Gateway balloon was performed slowly to prevent vascular dissection or rupture. When post-stenting angiography showed a filling defect, we considered the defect to be due to acute instent thrombosis and immediately attempted thrombolysis by administering Abciximab (4 mg) (Reopro; Centocor, Leiden, Netherlands) intra-arterially through a guiding catheter. Angiography was performed 10 minutes later for detection of undissolved thrombus. Repeat Abciximab boluses (2 mg) were administered until complete thrombolysis was achieved. Complete dissolution of the acute in-stent thrombus was deemed to have occurred when no filling defect was identified on subsequent angiography, and if there were no complications, the procedure was completed. Immediately after the therapeutic procedure, we obtained the detailed neurologic history and performed a complete examination of all patients. The patients underwent non-enhanced brain CT for evaluation of possible hemorrhagic complications. Following endovascular stent placement, patients were transferred to a stroke intensive care unit for strict control of BP for prevention of hyperperfusion syndrome. After the procedure, patients were administered aspirin 100 mg and clopidogrel 75 mg daily. Lowmolecular-weight nadroparin calcium (Fraxiparine; GlaxoSmithKline, France) 2850 IU was also administered subcutaneously three times per day for at least three days. In most cases, a clopidogrel resistance test was performed approximately 24 hours after drug administration according to our protocol for PTAS. We used the VerifyNow-p2y12 rapid analyzer for measurement of platelet inhibition rate. We defined clopidogrel resistance as percentage platelet inhibition 50% of the stenotic segment immediately after PTAS. Significant in-stent restenosis (ISR) was defined as a stenotic lesion involving more than 50% of the vessel, even if the patient was asymptomatic. For evaluation of clinical outcome of stroke patients, the NIHSS was checked on admission and seven days after the procedure. In addition, clinical functional outcome was assessed upon discharge from the hospital or at the last clinical visit using the modified Rankin scale (mRS). A score of 2 was considered a favorable outcome. Patients were followed once a month
513 postoperatively to check for further cerebrovascular events or stroke recurrence. Among the patients, several important outcomes were compared between two patient groups according to the type of stent. Differences were compared using Chi-square test or Fisher’s exact test for categorical variables, as appropriate. All reported probability (p) values were two-sided, and a p value 50%) was observed in the two patients (11.1%). One patient presented with asymptomatic ISR. Although an arterial lumen reduction of 95% was estimated, he refused retreatment (Figure 2). The other patient experienced TIA secondary to severe ISR nine months after PTAS. Bypass surgery was chosen for treatment of cerebral hypoperfusion because of intracranial tandem stenosis.
Comparison between BESs and WSs The patients were stratified according to whether they received a WS or BES. A summary of characteristics and clinical outcomes according to the type of stent is shown in Table 3. No patient treated with WS suffered from a CCF or procedural morbidity/mortality; however, there were two cases of CCF (13.3%) and procedural morbidity/mortality (13.3%) in patients treated with BES. A favorable outcome (mRS 2) was obtained in 13 of 15 patients treated with BES (86.7%) and 10 of 11 patients treated with WS (90.9%) at the last follow-up. The overall rates of significant ISR (>50%) in each group were 10.0% (BES) and 12.5% (WS), respectively. During the observation period, there were no further cerebrovascular events in the WS group (0%) and stroke recurrence occurred in two patients treated with BES (15.4%). There was no significant difference between the BES and SES groups for any outcome.
Discussion Certainly, extracranial carotid occlusive disease is an important risk factor for and is thought to be the cause in up to 20% of ischemic strokes.12,13 It is also
35/M 73/M 65/M 60/M 73/M 59/M 56/M 71/F
72/M 64/M 61/M 67/M 57/M 66/F
1 2 3 4 5 6 7 8
9 10 11 12 13 14
Lt petrous Lt petrous Rt cavernous Rt petrous Lt petrous Lt cavernous
Rt cavernous Rt petrocavernous Rt cavernous Lt cavernous Rt petrocavernous Rt cavernous Lt petrous Rt cavernous
Stenotic lesion
70 80 90 70 70 70
90 90 80 80 80 80 80 70
Preop
10 10 10 20 10 10
10 10 5 10 10 40 5 10
Postop
13 2 70 20 10 3
5 17 10 15 25 2 10 4
Time from symptom onset to stenting (days)
Flexmaster Flexmaster Flexmaster Flexmaster Flexmaster Flexmaster
Wingspan Wingspan Wingspan Wingspan Wingspan 2 Wingspan Flexmaster Flexmaster
Used stent None None None None None None None CCF, IST, massive ICH None None None None None CCF
Complications
2 3 4 0 4 2
2 1 0 2 0 4 2 4
Initial
2 3 0 0 2 2
2 0 0 0 0 4 2 6
7 days
NIHSS score
1 2 1 0 2 2
0 0 1 0 0 3 2 4
mRS at last follow-up
No ISR at 52 Not available Not available Severe ISR at 5 No ISR at 10 No ISR at 6
No ISR at 4 No ISR at 22 No ISR at 18 Severe ISR at 23 No ISR at 21 Not available No ISR at 16 Not available
Angiography
Follow up (months)
No for 52 No for 15 No for 3 TIA at 9 No for 73 No for 8
No for 26 No for 31 No for 18 No for 35 No for 44 Follow-up loss Embolic infarct at 16 Follow-up loss
Ischemic event
NIHSS: National Institutes of Health Stroke Scale; mRS: modified Rankin scale score; Rt: right; ISR: in-stent restenosis; Lt: left; CCF: carotid-cavernous fistula; IST: in-stent thrombosis; ICH: intracranial hemorrhage; TIA: transient ischemic attack; Preop: preoperative; Postop: postoperative; M: male; F: female.
Age/Sex
Patient no.
Stenosis (%)
Table 2. Characteristics and clinical outcomes of patients with minor stroke and an NIHSS score of 4.
Ko et al. 515
516
Interventional Neuroradiology 21(4)
Figure 1. Patient 3 in Table 1. A 62-year-old, right-handed male presented with repeated transient ischemic attacks despite antiplatelet therapy. (a) Pre-stenting digital subtraction angiography shows 95% stenosis at the petrous portion. (b), (c) Unsubtracted and subtracted images acquired immediately after stent-assisted angioplasty with a Wingspan self-expansible stent system show that the stenotic portion is well dilated (approximately 10% residual stenosis) with substantial improvement of the left anterior and middle cerebral artery flow. During the immediate postprocedural period the patient was found to have right hemiparesis, facial droop and dysarthria, suggestive of a hyperperfusion syndrome, which resolved with blood pressure control. (d) Computed tomography perfusion scans with time to peak (TTP) and mean transit time (MTT) obtained before and after stent-assisted angioplasty. Significant asymmetry between the right and left hemispheres with striking hypoperfusion of the left internal carotid artery (ICA) territory shows substantial improvement after stentassisted angioplasty. (e) Eight-month follow-up angiogram shows the patient’s stent site without significant in-stent restenosis.
known that the natural history of intracranial ICA stenosis is associated with a higher risk of stroke, similar to that of cervical ICA stenosis.14,15 According to the previous report about natural history of the intracranial ICA stenosis, only 33% of the patients were alive and free from subsequent cerebral vascular events at the end of the mean follow-up of 30 months. Forty-three percent of the patients died during follow-up: 36% from stroke and 44% from cardiac disease. Furthermore, the annual ipsilateral stroke rate for patients with this lesion was 7.6% per year. They concluded that intracranial ICA stenosis was a marker of extensive cerebrovascular and systemic atherosclerotic disease, especially coronary artery disease.15 In the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) study reported by Chimowitz et al.,11 despite risk factor modification and the use of warfarin or aspirin, the rate of ipsilateral stroke to intracranial stenosis (>70%) was 23% in the first year and 25% in the second.
Well-conducted prospective randomized trials established that carotid endarterectomy was an effective means of future stroke prevention in at-risk populations with significant carotid disease. With advances in endovascular techniques and devices, carotid angioplasty and stenting has been established as a useful alternative to carotid endarterectomy for treatment of extracranial carotid artery stenosis. Unlike favorable results of carotid angioplasty and stenting for treatment of extracranial carotid artery stenosis, endovascular approaches for treatment of refractory symptomatic intracranial arterial stenosis are associated with a significant incidence of immediate postoperative complications (20.9%), permanent neurological morbidity (6.6%), and death (2.2%).16,17 Reasons for these results include distal embolization, vessel rupture, occlusion in perforating arteries, and in-stent thrombosis. However, considering the low mortality and morbidity rate of PTA or stent placement for cervical ICA stenosis, we speculated that the risk of intracranial extradural
Ko et al.
517
Figure 2. Patient 4 in Table 2. A 60-year-old man with acute infarct resulting from internal carotid artery (ICA) stenosis. (a) Initial diffusion-weighted image shows a small infarction in the left periventricular internal border zone. (b) Left ICA angiography shows a severe degree of stenosis (80%) at the cavernous portion. (c) After stent-assisted angioplasty with two Wingspan self-expansible stent systems, the stenotic portion is well dilated with approximately 10% residual stenosis. (d) Left ICA angiogram obtained 23 months later shows a diffuse in-stent restenosis throughout the stented segment of the ICA, most severely within the anterior portion of the stent. (e) The left ICA territory is supplied by the right ICA through the anterior communicating artery.
Table 3. Comparison between balloon-expandable coronary stents and Wingspan self-expandable intracranial stents.
CCF Procedural morbidity/mortality mRS 2 at last follow-up Significant ISR at follow-up Subsequent ischemic event
Balloon-expandable coronary stents (%) (n ¼ 15)
Wingspan self-expandable intracranial stents (%) (n ¼ 11)
p value
2/15 (13.3) 2/15 (13.3) 13/15 (86.7) 1/10 (10.0) 2/13 (15.4)
0/11 (0) 0/11 (0) 10/11 (90.9) 1/8 (12.5) 0/9 (0)
0.207 0.207 0.738 0.819 0.207
CCF: carotid-cavernous fistula; mRS: modified Rankin scale score; ISR: in-stent restenosis.
atherosclerotic stenosis associated with PTAS is not so high, unlike that of the lesion in other location. Also, the risk of occlusion of a perforating artery or vessel rupture seems very low because the extradural ICA is covered by the bone structure or dura mater and does not have important perforating arteries, in contrast to the middle cerebral artery or basilar artery stenosis.18–20 In a study of angioplasty or stenting for intracranial
ICA stenosis (54 patients with 13 cavernous or 41 petrous ICA stenosis), Ito et al.21 reported that at a mean follow-up of 29.9 months, 48 (88.9%) of their 54 patients had an excellent outcome. The morbidity rate was 13%, and approximately 10% of the patients experienced complications after the initial angioplasty/stenting. The postoperative permanent morbidity/mortality rate was 7.7% in our series.
518 These figures still seem a little advantageous when compared with the critical morbidity/mortality of the natural history or best medical therapy of the disease, as previously described.2,11,22 However, we should still pay attention in order to prevent procedure-related thromboembolic complications, which caused permanent morbidity/mortality in the current series. According to the final results of SAMMPRIS trial,3 the occurrence of primary endpoints in the medical group versus PTAS group was 5.8% versus 14.7% at day 30 (p ¼ 0.0016), 12.6% versus 19.7% at year 1 (p ¼ 0.0428), 14.1% versus 20.6% at year 2 (p ¼ 0.07), and 14.9% versus 23.9% at year 3 (p ¼ 0.0193). The primary endpoint was any of the following: stroke or death within 30 days after enrollment, ischemic stroke in the territory of the qualifying artery beyond 30 days of enrollment, or stroke or death within 30 days after a revascularization procedure of the qualifying lesion during follow-up. In our series, the 30-day major adverse events (major stroke and death) rate was 7.7% and stroke rate beyond 30 days was 9.1% during the observation period of a mean of 29.9 months (range, 3–73 months), corresponding to 16.8% at year 2.5 as a primary endpoint in the SAMMPRIS trial. Although it is unreasonable to compare directly the results between the SAMMPRIS trial and our series since the basic characteristics are different, our results also appear to fail to exceed that of the medical group in the SAMMPRIS trial. The much lower rate of stroke in the medical group in SAMMPRIS compared with patients in WASID who had similar entrance criteria is probably explained by differences in medical treatment in these trials.11,23,24 Patients in WASID were treated with usual risk factor management and either aspirin or warfarin, whereas patients in SAMMPRIS were treated with intensive risk factor management and combined aspirin and clopidogrel for 90 days followed by aspirin alone.1,11 We also did not apply the intensive risk factor management to enrolled patients. This finding suggests that the intensive risk factor management could have played an important part in lowering the risk of stroke in these patient groups. Although the three-year follow-up of the Stenting and Angioplasty With Protection in Patients at High Risk for Endarterectomy (SAPPHlRE) trial revealed only 4% recurrent stenosis rate after carotid angioplasty and stenting for extracranial ICA stenosis,25 data from the Stenting of Symptomatic Atherosclerotic Lesions in the Vertebral or Intracranial Arteries (SSYLVIA) study showed a restenosis rate of 32.4%.26 According to recent reports, the restenosis rate of the intracranial stenting is considerably lower. Fiorella et al.16 reported a 12.5% restenosis or occlusion rate in the seven-year experience of 44 patients treated with BESs in the vertebrobasilar system. A recently published Latin American series of 32 patients treated with BESs reported a restenosis rate of 8.7% for an average follow-up period of 10
Interventional Neuroradiology 21(4) months.27 Terada et al.,28 however, reported that no restenosis was encountered in nine patients with stenosis of the petrous or cavernous portion of the ICA on follow-up angiography performed at three to six months after PTAS. They supposed the excellent long-term patency after procedure was attributable to anatomical characteristics of these lesions, such as larger diameter size and shorter length compared with the remaining intracranial stenosis. Actually, all lesions were successfully dilated after stenting, as is apparent from the 2.2% residual stenosis measured immediately after stenting. In our series, 10% residual stenosis was measured immediately after stenting, and these differences between residual stenosis may explain slightly higher rate of restenosis (11.1%) in our series than that reported previously. Although ISR/occlusion resulted in recurrent neurological symptoms and sometimes necessitated retreatment, this phenomenon was not a major contributor to permanent morbidity in most patients.6,16,21 The previous data clearly indicate that periprocedural morbidity, not delayed ISR/occlusion, is the major downfall of BES as an effective strategy for treatment of symptomatic intracranial atherosclerotic stenosis. In other words, problems caused by ISR are most often benign, and likely to have the opportunity of treatment before the occurrence of morbidity or mortality. Similarly, in our series, both the patients accompanied by ISR did not have any deficits caused by it. WSs have been available in our hospital since April 2010. During the observation period, there were no further cerebrovascular events in the WS group (0%) and stroke recurrence occurred in two patients treated with BES (15.4%). However, there was no statistically significant difference between both groups for any outcome, although overall, slightly favorable outcomes seemed to be achieved in the WS group, compared to the BES group. In our series, PTAS for severe stenosis (>70%) involving the petrous or cavernous ICA was technically successful in all cases and the postoperative permanent morbidity/mortality rate was 7.7%. No further cerebrovascular events occurred in 90.9% of patients during an average period of 29.9 months. The current study showed that symptomatic patients with petrous or cavernous ICA stenosis of >70% could benefit from PTAS, although these findings should be confirmed in a larger study with multivariate logistic regression analysis.
Conclusions PTAS for severe stenosis (>70%) involving the intracranial extradural ICA showed good technical feasibility and favorable clinical outcome in patients with TIA or minor stroke. However, periprocedural morbidity and mortality, which represents the primary limitation of this modality for treatment of intracranial atherosclerotic stenosis, is an issue that must be resolved in order to achieve a favorable outcome.
Ko et al. Acknowledgments JKK and THL were primarily responsible for study design, collecting data and drafting the manuscript. CHC, SHC, BKC, WHC, THK, SMS, and HJC contributed significantly to this report by critically reading the manuscript and providing many helpful suggestions. All of the authors read and approved this manuscript to be submitted for publication to this journal.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Conflict of interest None declared.
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VOLUME 21 - No. 4 august 2015 ISSN 1591-0199 Online ISSN 2385-2011
Volume 21, No. 4, Pages 421 - 560, 2015
Journal of Peritherapeutic Neuroradiology, Surgical Procedures and Related Neurosciences Official Journal of: WFITN - World Federation of Interventional and Therapeutic Neuroradiology AAFITN - Asian & Australasian Federation of Interventional & Therapeutic Neuroradiology SAWITN - South American Working Group in Interventional and Therapeutic Neuroradiology The Chinese INR Coordinating Committee of the Chinese Doctor Association INSHCM - Interventional Neuroradiology Society of HCM City, Viet Nam Journal sponsored by JSNET - Japanese Society of Neuro Endovascular Therapy FIO - Italian Federation of Ozone Therapy Interventional Neuroradiology is published in cooperation with the American Journal of Neuroradiology
Original Article
Percutaneous transluminal angioplasty and stenting for severe stenosis of the intracranial extradural internal carotid artery causing transient ischemic attack or minor stroke
Interventional Neuroradiology 2015, Vol. 21(4) 511–519 ! The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1591019915582379 ine.sagepub.com
Jun Kyeung Ko1, Chang Hwa Choi1, Seung Heon Cha1, Byung Kwan Choi1, Won Ho Cho1, Tae Ho Kang2, Sang Min Sung2, Han Jin Cho2 and Tae Hong Lee3
Abstract The purpose of this study is to assess the technical feasibility and clinical efficacy of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic stenosis of the intracranial extradural (petrous and cavernous) internal carotid artery (ICA). Review of medical records identified 26 consecutive patients who underwent PTAS using a balloon-expandable coronary stent (n ¼ 15, 57.7%) or a Wingspan self-expandable stent (n ¼ 11, 42.3%) for treatment of severe stenosis (>70%) involving the intracranial extradural ICA. The inclusion criteria were transient ischemic attack with an ABCD2 score of 3 (n ¼ 12, 46.2%) or minor stroke with an NIHSS score of 4 (n ¼ 14, 53.8%). Technical success rates, complications, and angiographic and clinical outcomes were analyzed retrospectively. PTAS was technically successful in all patients. The mean stenosis ratio decreased from 77.1% to 10.0% immediately after PTAS. The overall incidence of procedural complications was 23.1%, and the postoperative permanent morbidity/mortality rate was 7.7%. A total of 22 patients were tracked over an average period of 29.9 months. During the observation period, 20 patients (90.9%) had no further cerebrovascular events and stroke recurrence occurred in two patients (9.1%), resulting in an annual stroke risk of 3.7%. Two cases (11.1%) of significant in-stent restenosis (>50%) were found on follow-up angiography (n ¼ 18). PTAS for severe stenosis (>70%) involving the intracranial extradural ICA showed a good technical feasibility and favorable clinical outcome in patients with transient ischemic attack or minor stroke.
Keywords Stents, angioplasty, carotid stenosis, transient ischemic attack, stroke
Introduction The Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) trial was designed to assess whether percutaneous transluminal angioplasty and stenting (PTAS) plus aggressive medical treatment is more effective than aggressive medical treatment alone in patients with recent transient ischemic attack (TIA) or stroke (within the past 30 days) attributed to 70–99% atherosclerotic intracranial arterial stenosis.1 Enrollment in SAMMPRIS began November 25, 2008, but was stopped for safety concerns April 5, 2011, because the 30-day rate of stroke and death was higher in the PTAS group.2 According to the recently reported final results of SAMMPRIS, the early benefit of aggressive medical treatment compared with PTAS
in high-risk patients with intracranial arterial stenosis persisted over a median duration of 32.4 months of follow-up in this trial.3 So far the results of intracranial stenting for this lesion have been very disappointing.
1
Department of Neurosurgery, Medical Research Institute, Pusan National University Hospital, Korea 2 Department of Neurology, Medical Research Institute, Pusan National University Hospital, Korea 3 Department of Diagnostic Radiology, Medical Research Institute, Pusan National University Hospital, Korea Corresponding author: Tae Hong Lee, Department of Diagnostic Radiology, Pusan National University Hospital, 305 Gudeok-Ro, Seo-Gu, Busan, 602-739, Republic of Korea. Email: [email protected]
512 Despite the discouraging final results of SAMMPRIS, there are still subgroups of patients at high risk of stroke on aggressive medical treatment. Several publications report promising outcomes in a subset of patients with severe intracranial arterial stenosis, rendering the efficacy of PTAS contentious.4–8 At this point, we thought that the subgroup analysis according to the lesion location should be performed in order to improve the clinical outcome of intracranial stenting, and noticed the intracranial extradural (petrous and cavernous) segment of the internal carotid artery (ICA). The aim of this study was to assess the technical feasibility and clinical efficacy of PTAS for severe stenosis (>70%) of the intracranial extradural ICA in TIA or minor stroke patients.
Materials and methods Patient population and inclusion criteria A total of 77 symptomatic patients with severe stenosis of the intracranial artery underwent PTAS at our institution between 2006 and 2013. The lesions consisted of 29 distal ICAs, 25 middle cerebral arteries, 16 vertebral arteries, and seven basilar arteries. Among these patients, 26 consecutive patients with stenosis involving the cavernous or petrous portion of the ICA were reviewed retrospectively. Owing to the retrospective nature, the present study is exempt in accord with the institutional review board standards of our institution. The inclusion criteria were TIA with an ABCD2 score of 3 or minor stroke with ICA stenosis of >70%. All patients were evaluated by experienced neurologists and were determined to have clinical symptoms attributable to ICA stenosis. All patients underwent screening with brain magnetic resonance imaging (MRI) and computed tomography (CT) in order to exclude other intracranial diseases, such as hemorrhage or tumors. TIA was defined as an acute transient focal neurological deficit caused by vascular disease that completely reversed within 24 hours and caused no acute lesion on diffusion-weighted imaging (DWI).9 In TIA patients, ABCD2 scoring was performed by assigning points as follows: age (60 years, one point); blood pressure (BP) at first assessment after symptom onset (systolic BP of 140 mm Hg or diastolic BP of 90 mm Hg, one point); clinical features of TIA (unilateral weakness, two points; speech impairment without weakness, one point); duration of symptoms (60 minutes, two points; 10–59 minutes, one point); diabetes (one point).10 Minor stroke was defined as any acute neurological deficit with a new lesion by DWI and a United States National Institutes of Health Stroke Scale (NIHSS) score of 4. All patients underwent digital subtraction angiography before PTAS. Stenosis percentages were calculated by measuring the narrowest vessel diameter visualized within stenosis and expressing this as a ratio of its proximal diameter.11
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Endovascular procedure All patients received dual antiplatelet medication including 75 mg of clopidogrel and 100 mg of aspirin each day over five days or a loading dose of 300 mg of clopidogrel and 300 mg of aspirin at least 12 hours before endovascular treatment. Interventional procedures were performed in the neuroangiography room, which is equipped with a digital subtraction angiography system (Axiom Artis, Siemens, Germany). All angiographic procedures were performed using a transfemoral approach under local anesthesia using an electrocardiogram, arterial oxygen saturation, and BP monitoring. Prior to the therapeutic procedure, patients were administered a systemic heparinization and a bolus injection of heparin 3000 IU. An additional 1000 IU bolus of heparin was administered every hour in order to maintain an activated coagulation time (ACT) of >200 seconds throughout the procedure. Coaxial catheter-flushing fluid was mixed with heparin at a concentration of 1000 IU of heparin per 1000 ml of saline. Up until April 2010, a balloon-expandable coronary stent (BES) was the only stent available in our institute. Wingspan self-expandable intracranial stent (WS) then became available, and could be used only during the remainder of the study period because of public health insurance regulation. A 6 F guiding catheter (Envoy; Cordis Corporation, USA) was positioned in the distal cervical ICA, and preprocedural angiograms were then obtained in biplanes. The stenotic segment was crossed with a 205 cm long for BES or a 300 cm long for WS, 0.014 inch thick microwire (Transcend 14; Target/Boston Scientific, Natick, MA, USA) placed in the insular portion of the middle cerebral artery to ensure maximal support.
BES Angioplasty and stenting were performed simultaneously using a BES in all patients. The diameter and length of each device were chosen according to the diameter of the normal vessel and the extension of the stenosis. The balloon was slowly inflated using a multistage technique to prevent vessel dissection or rupture. When no gap was present between the stent and the parent artery, deployment was terminated, followed by a 30-minute wait to identify possible complications, such as acute in-stent thrombosis or previously undetected vascular rupture.
WS Before stent deployment, predilation was performed with a Gateway balloon (Boston Scientific Corporation, USA), which was slowly inflated to 80% of the diameter of the reference vessel. A slightly oversized (0.5–1.0 mm) stent was used to enable complete apposition to the vessel wall. The appropriate length was chosen in a way that would ensure coverage
Ko et al. of the stenotic lesion at least 3 mm beyond its proximal and distal extremities. A WS delivery catheter was advanced across the lesion using the road map, and the stent was slowly deployed. If a significant residual stenosis was found on post-stenting angiography, in-stent balloon angioplasty using a Gateway balloon was performed slowly to prevent vascular dissection or rupture. When post-stenting angiography showed a filling defect, we considered the defect to be due to acute instent thrombosis and immediately attempted thrombolysis by administering Abciximab (4 mg) (Reopro; Centocor, Leiden, Netherlands) intra-arterially through a guiding catheter. Angiography was performed 10 minutes later for detection of undissolved thrombus. Repeat Abciximab boluses (2 mg) were administered until complete thrombolysis was achieved. Complete dissolution of the acute in-stent thrombus was deemed to have occurred when no filling defect was identified on subsequent angiography, and if there were no complications, the procedure was completed. Immediately after the therapeutic procedure, we obtained the detailed neurologic history and performed a complete examination of all patients. The patients underwent non-enhanced brain CT for evaluation of possible hemorrhagic complications. Following endovascular stent placement, patients were transferred to a stroke intensive care unit for strict control of BP for prevention of hyperperfusion syndrome. After the procedure, patients were administered aspirin 100 mg and clopidogrel 75 mg daily. Lowmolecular-weight nadroparin calcium (Fraxiparine; GlaxoSmithKline, France) 2850 IU was also administered subcutaneously three times per day for at least three days. In most cases, a clopidogrel resistance test was performed approximately 24 hours after drug administration according to our protocol for PTAS. We used the VerifyNow-p2y12 rapid analyzer for measurement of platelet inhibition rate. We defined clopidogrel resistance as percentage platelet inhibition 50% of the stenotic segment immediately after PTAS. Significant in-stent restenosis (ISR) was defined as a stenotic lesion involving more than 50% of the vessel, even if the patient was asymptomatic. For evaluation of clinical outcome of stroke patients, the NIHSS was checked on admission and seven days after the procedure. In addition, clinical functional outcome was assessed upon discharge from the hospital or at the last clinical visit using the modified Rankin scale (mRS). A score of 2 was considered a favorable outcome. Patients were followed once a month
513 postoperatively to check for further cerebrovascular events or stroke recurrence. Among the patients, several important outcomes were compared between two patient groups according to the type of stent. Differences were compared using Chi-square test or Fisher’s exact test for categorical variables, as appropriate. All reported probability (p) values were two-sided, and a p value 50%) was observed in the two patients (11.1%). One patient presented with asymptomatic ISR. Although an arterial lumen reduction of 95% was estimated, he refused retreatment (Figure 2). The other patient experienced TIA secondary to severe ISR nine months after PTAS. Bypass surgery was chosen for treatment of cerebral hypoperfusion because of intracranial tandem stenosis.
Comparison between BESs and WSs The patients were stratified according to whether they received a WS or BES. A summary of characteristics and clinical outcomes according to the type of stent is shown in Table 3. No patient treated with WS suffered from a CCF or procedural morbidity/mortality; however, there were two cases of CCF (13.3%) and procedural morbidity/mortality (13.3%) in patients treated with BES. A favorable outcome (mRS 2) was obtained in 13 of 15 patients treated with BES (86.7%) and 10 of 11 patients treated with WS (90.9%) at the last follow-up. The overall rates of significant ISR (>50%) in each group were 10.0% (BES) and 12.5% (WS), respectively. During the observation period, there were no further cerebrovascular events in the WS group (0%) and stroke recurrence occurred in two patients treated with BES (15.4%). There was no significant difference between the BES and SES groups for any outcome.
Discussion Certainly, extracranial carotid occlusive disease is an important risk factor for and is thought to be the cause in up to 20% of ischemic strokes.12,13 It is also
35/M 73/M 65/M 60/M 73/M 59/M 56/M 71/F
72/M 64/M 61/M 67/M 57/M 66/F
1 2 3 4 5 6 7 8
9 10 11 12 13 14
Lt petrous Lt petrous Rt cavernous Rt petrous Lt petrous Lt cavernous
Rt cavernous Rt petrocavernous Rt cavernous Lt cavernous Rt petrocavernous Rt cavernous Lt petrous Rt cavernous
Stenotic lesion
70 80 90 70 70 70
90 90 80 80 80 80 80 70
Preop
10 10 10 20 10 10
10 10 5 10 10 40 5 10
Postop
13 2 70 20 10 3
5 17 10 15 25 2 10 4
Time from symptom onset to stenting (days)
Flexmaster Flexmaster Flexmaster Flexmaster Flexmaster Flexmaster
Wingspan Wingspan Wingspan Wingspan Wingspan 2 Wingspan Flexmaster Flexmaster
Used stent None None None None None None None CCF, IST, massive ICH None None None None None CCF
Complications
2 3 4 0 4 2
2 1 0 2 0 4 2 4
Initial
2 3 0 0 2 2
2 0 0 0 0 4 2 6
7 days
NIHSS score
1 2 1 0 2 2
0 0 1 0 0 3 2 4
mRS at last follow-up
No ISR at 52 Not available Not available Severe ISR at 5 No ISR at 10 No ISR at 6
No ISR at 4 No ISR at 22 No ISR at 18 Severe ISR at 23 No ISR at 21 Not available No ISR at 16 Not available
Angiography
Follow up (months)
No for 52 No for 15 No for 3 TIA at 9 No for 73 No for 8
No for 26 No for 31 No for 18 No for 35 No for 44 Follow-up loss Embolic infarct at 16 Follow-up loss
Ischemic event
NIHSS: National Institutes of Health Stroke Scale; mRS: modified Rankin scale score; Rt: right; ISR: in-stent restenosis; Lt: left; CCF: carotid-cavernous fistula; IST: in-stent thrombosis; ICH: intracranial hemorrhage; TIA: transient ischemic attack; Preop: preoperative; Postop: postoperative; M: male; F: female.
Age/Sex
Patient no.
Stenosis (%)
Table 2. Characteristics and clinical outcomes of patients with minor stroke and an NIHSS score of 4.
Ko et al. 515
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Figure 1. Patient 3 in Table 1. A 62-year-old, right-handed male presented with repeated transient ischemic attacks despite antiplatelet therapy. (a) Pre-stenting digital subtraction angiography shows 95% stenosis at the petrous portion. (b), (c) Unsubtracted and subtracted images acquired immediately after stent-assisted angioplasty with a Wingspan self-expansible stent system show that the stenotic portion is well dilated (approximately 10% residual stenosis) with substantial improvement of the left anterior and middle cerebral artery flow. During the immediate postprocedural period the patient was found to have right hemiparesis, facial droop and dysarthria, suggestive of a hyperperfusion syndrome, which resolved with blood pressure control. (d) Computed tomography perfusion scans with time to peak (TTP) and mean transit time (MTT) obtained before and after stent-assisted angioplasty. Significant asymmetry between the right and left hemispheres with striking hypoperfusion of the left internal carotid artery (ICA) territory shows substantial improvement after stentassisted angioplasty. (e) Eight-month follow-up angiogram shows the patient’s stent site without significant in-stent restenosis.
known that the natural history of intracranial ICA stenosis is associated with a higher risk of stroke, similar to that of cervical ICA stenosis.14,15 According to the previous report about natural history of the intracranial ICA stenosis, only 33% of the patients were alive and free from subsequent cerebral vascular events at the end of the mean follow-up of 30 months. Forty-three percent of the patients died during follow-up: 36% from stroke and 44% from cardiac disease. Furthermore, the annual ipsilateral stroke rate for patients with this lesion was 7.6% per year. They concluded that intracranial ICA stenosis was a marker of extensive cerebrovascular and systemic atherosclerotic disease, especially coronary artery disease.15 In the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) study reported by Chimowitz et al.,11 despite risk factor modification and the use of warfarin or aspirin, the rate of ipsilateral stroke to intracranial stenosis (>70%) was 23% in the first year and 25% in the second.
Well-conducted prospective randomized trials established that carotid endarterectomy was an effective means of future stroke prevention in at-risk populations with significant carotid disease. With advances in endovascular techniques and devices, carotid angioplasty and stenting has been established as a useful alternative to carotid endarterectomy for treatment of extracranial carotid artery stenosis. Unlike favorable results of carotid angioplasty and stenting for treatment of extracranial carotid artery stenosis, endovascular approaches for treatment of refractory symptomatic intracranial arterial stenosis are associated with a significant incidence of immediate postoperative complications (20.9%), permanent neurological morbidity (6.6%), and death (2.2%).16,17 Reasons for these results include distal embolization, vessel rupture, occlusion in perforating arteries, and in-stent thrombosis. However, considering the low mortality and morbidity rate of PTA or stent placement for cervical ICA stenosis, we speculated that the risk of intracranial extradural
Ko et al.
517
Figure 2. Patient 4 in Table 2. A 60-year-old man with acute infarct resulting from internal carotid artery (ICA) stenosis. (a) Initial diffusion-weighted image shows a small infarction in the left periventricular internal border zone. (b) Left ICA angiography shows a severe degree of stenosis (80%) at the cavernous portion. (c) After stent-assisted angioplasty with two Wingspan self-expansible stent systems, the stenotic portion is well dilated with approximately 10% residual stenosis. (d) Left ICA angiogram obtained 23 months later shows a diffuse in-stent restenosis throughout the stented segment of the ICA, most severely within the anterior portion of the stent. (e) The left ICA territory is supplied by the right ICA through the anterior communicating artery.
Table 3. Comparison between balloon-expandable coronary stents and Wingspan self-expandable intracranial stents.
CCF Procedural morbidity/mortality mRS 2 at last follow-up Significant ISR at follow-up Subsequent ischemic event
Balloon-expandable coronary stents (%) (n ¼ 15)
Wingspan self-expandable intracranial stents (%) (n ¼ 11)
p value
2/15 (13.3) 2/15 (13.3) 13/15 (86.7) 1/10 (10.0) 2/13 (15.4)
0/11 (0) 0/11 (0) 10/11 (90.9) 1/8 (12.5) 0/9 (0)
0.207 0.207 0.738 0.819 0.207
CCF: carotid-cavernous fistula; mRS: modified Rankin scale score; ISR: in-stent restenosis.
atherosclerotic stenosis associated with PTAS is not so high, unlike that of the lesion in other location. Also, the risk of occlusion of a perforating artery or vessel rupture seems very low because the extradural ICA is covered by the bone structure or dura mater and does not have important perforating arteries, in contrast to the middle cerebral artery or basilar artery stenosis.18–20 In a study of angioplasty or stenting for intracranial
ICA stenosis (54 patients with 13 cavernous or 41 petrous ICA stenosis), Ito et al.21 reported that at a mean follow-up of 29.9 months, 48 (88.9%) of their 54 patients had an excellent outcome. The morbidity rate was 13%, and approximately 10% of the patients experienced complications after the initial angioplasty/stenting. The postoperative permanent morbidity/mortality rate was 7.7% in our series.
518 These figures still seem a little advantageous when compared with the critical morbidity/mortality of the natural history or best medical therapy of the disease, as previously described.2,11,22 However, we should still pay attention in order to prevent procedure-related thromboembolic complications, which caused permanent morbidity/mortality in the current series. According to the final results of SAMMPRIS trial,3 the occurrence of primary endpoints in the medical group versus PTAS group was 5.8% versus 14.7% at day 30 (p ¼ 0.0016), 12.6% versus 19.7% at year 1 (p ¼ 0.0428), 14.1% versus 20.6% at year 2 (p ¼ 0.07), and 14.9% versus 23.9% at year 3 (p ¼ 0.0193). The primary endpoint was any of the following: stroke or death within 30 days after enrollment, ischemic stroke in the territory of the qualifying artery beyond 30 days of enrollment, or stroke or death within 30 days after a revascularization procedure of the qualifying lesion during follow-up. In our series, the 30-day major adverse events (major stroke and death) rate was 7.7% and stroke rate beyond 30 days was 9.1% during the observation period of a mean of 29.9 months (range, 3–73 months), corresponding to 16.8% at year 2.5 as a primary endpoint in the SAMMPRIS trial. Although it is unreasonable to compare directly the results between the SAMMPRIS trial and our series since the basic characteristics are different, our results also appear to fail to exceed that of the medical group in the SAMMPRIS trial. The much lower rate of stroke in the medical group in SAMMPRIS compared with patients in WASID who had similar entrance criteria is probably explained by differences in medical treatment in these trials.11,23,24 Patients in WASID were treated with usual risk factor management and either aspirin or warfarin, whereas patients in SAMMPRIS were treated with intensive risk factor management and combined aspirin and clopidogrel for 90 days followed by aspirin alone.1,11 We also did not apply the intensive risk factor management to enrolled patients. This finding suggests that the intensive risk factor management could have played an important part in lowering the risk of stroke in these patient groups. Although the three-year follow-up of the Stenting and Angioplasty With Protection in Patients at High Risk for Endarterectomy (SAPPHlRE) trial revealed only 4% recurrent stenosis rate after carotid angioplasty and stenting for extracranial ICA stenosis,25 data from the Stenting of Symptomatic Atherosclerotic Lesions in the Vertebral or Intracranial Arteries (SSYLVIA) study showed a restenosis rate of 32.4%.26 According to recent reports, the restenosis rate of the intracranial stenting is considerably lower. Fiorella et al.16 reported a 12.5% restenosis or occlusion rate in the seven-year experience of 44 patients treated with BESs in the vertebrobasilar system. A recently published Latin American series of 32 patients treated with BESs reported a restenosis rate of 8.7% for an average follow-up period of 10
Interventional Neuroradiology 21(4) months.27 Terada et al.,28 however, reported that no restenosis was encountered in nine patients with stenosis of the petrous or cavernous portion of the ICA on follow-up angiography performed at three to six months after PTAS. They supposed the excellent long-term patency after procedure was attributable to anatomical characteristics of these lesions, such as larger diameter size and shorter length compared with the remaining intracranial stenosis. Actually, all lesions were successfully dilated after stenting, as is apparent from the 2.2% residual stenosis measured immediately after stenting. In our series, 10% residual stenosis was measured immediately after stenting, and these differences between residual stenosis may explain slightly higher rate of restenosis (11.1%) in our series than that reported previously. Although ISR/occlusion resulted in recurrent neurological symptoms and sometimes necessitated retreatment, this phenomenon was not a major contributor to permanent morbidity in most patients.6,16,21 The previous data clearly indicate that periprocedural morbidity, not delayed ISR/occlusion, is the major downfall of BES as an effective strategy for treatment of symptomatic intracranial atherosclerotic stenosis. In other words, problems caused by ISR are most often benign, and likely to have the opportunity of treatment before the occurrence of morbidity or mortality. Similarly, in our series, both the patients accompanied by ISR did not have any deficits caused by it. WSs have been available in our hospital since April 2010. During the observation period, there were no further cerebrovascular events in the WS group (0%) and stroke recurrence occurred in two patients treated with BES (15.4%). However, there was no statistically significant difference between both groups for any outcome, although overall, slightly favorable outcomes seemed to be achieved in the WS group, compared to the BES group. In our series, PTAS for severe stenosis (>70%) involving the petrous or cavernous ICA was technically successful in all cases and the postoperative permanent morbidity/mortality rate was 7.7%. No further cerebrovascular events occurred in 90.9% of patients during an average period of 29.9 months. The current study showed that symptomatic patients with petrous or cavernous ICA stenosis of >70% could benefit from PTAS, although these findings should be confirmed in a larger study with multivariate logistic regression analysis.
Conclusions PTAS for severe stenosis (>70%) involving the intracranial extradural ICA showed good technical feasibility and favorable clinical outcome in patients with TIA or minor stroke. However, periprocedural morbidity and mortality, which represents the primary limitation of this modality for treatment of intracranial atherosclerotic stenosis, is an issue that must be resolved in order to achieve a favorable outcome.
Ko et al. Acknowledgments JKK and THL were primarily responsible for study design, collecting data and drafting the manuscript. CHC, SHC, BKC, WHC, THK, SMS, and HJC contributed significantly to this report by critically reading the manuscript and providing many helpful suggestions. All of the authors read and approved this manuscript to be submitted for publication to this journal.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Conflict of interest None declared.
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