Role of Balloon-Expandable Stents in Intracranial Atherosclerotic Disease in a Series of 182 Patients
Background and Purpose—To demonstrate the safety and efficacy of balloon-expandable intracranial stents in patients with intracranial atherosclerotic lesions (>70% stenosis) who were symptomatic despite being on optimum medical therapy.
Methods—Between April 2004 and May 2012, 182 patients underwent intracranial stenting in our institution. All patients had symptoms despite being on optimum medical therapy. Clinical follow-up was done at 1, 3, 6, and 12 months. Angiographic follow-up was done at 1 year in 121 patients.
Results—Technical success was achieved in 97.44% of the cases. The incidence of all strokes at 1 month after procedure was 11 (5.64%), of which 2 (1.02%) were major, both related to stent thrombosis not responding to tirofiban, and 9 (4.61%) were minor. Periprocedural minor stroke was seen in 9 patients. There were 2 deaths in our study (mortality=1.09%).
Conclusions—Treatment of intracranial atherosclerotic disease with balloon-expandable intracranial stents is a safe and effective method with acceptable adverse events, especially in patients who failed medical therapy and were symptomatic despite being on optimum medical therapy.
Intracranial atherosclerosis is a high-risk cause of ischemic stroke. Intracranial atherosclerotic disease accounts for 30% to 50% of strokes in the Asian population.1 Hence, the impact of this disease is more relevant in the Asian population compared with other ethnicities. In our present study, we evaluated the procedural safety and success of balloon-expandable intracranial stent placement in patients with symptomatic severe lesions (>70% stenosis) who had symptoms despite being on optimum medical therapy.
Patients and Methods
The present study is a retrospective analysis of patients from a prospectively collected institutional review board–approved database. From April 2004 to May 2012, 182 patients with 195 intracranial atherosclerotic lesions underwent intracranial stenting with balloon-expandable intracranial stents. There were 111 men and 71 women, with age group ranging from 18 to 75 years.
Inclusion criteria for intracranial stent placement were severe (>70% stenosis on digital subtraction angiography) atheromatous lesions and symptomatic despite being on optimum medical therapy (aspirin 150 mg/d and clopidogrel 75 mg with atorvastatin 40 mg/d for at least 1 week). Symptoms were classified as recurrent transient ischemic attacks (TIAs; 136 of 182 patients), recurrent minor strokes (35 of 182 patients), and first TIA or minor stroke with patient already on optimum medical therapy (11 of 182 patients).
Exclusion criteria were <18 or >75 years of age, serum creatinine >221 µmol/L, presence of major stroke with disability, known hypersensitivity to contrast agent, very tortuous anatomy, middle cerebral artery bifurcation lesions (lesions beyond M1), associated intraluminal thrombus, and extensive associated small vessel disease, especially ostial disease in branches arising from the lesion.
Demographic features, risk factors, and location of the lesion were recorded. Brain MRI was performed on all patients before stent placement. Foci of restricted diffusion, suggestive of acute infarcts on diffusion-weighted imaging, were seen in 63 patients.
Stenting for 2 intracranial lesions (double stenting) was done in 13 Patients. Ten patients had tandem lesions (ICA origin+middle cerebral artery or intracranial ICA in 5 patients and vertebral ostial+intracranial VA or basilar in 5 patients). Stenting was done in the same session (tandem stenting) in the 5 patients with tandem vertebrobasilar lesions. In the 5 patients with ICA origin stenosis and ipsilateral M1 or intracranial lesions, stenting of the proximal lesion was done in the first stage followed by the distal lesion after 2 weeks.
All patients were followed clinically at fortnightly intervals for 1 month, monthly intervals for 6 months, and 3 monthly intervals thereafter. A 1-year follow-up digital subtraction angiogram was advised in all patients but could be done in 121 patients.
Association of 9 variables, ie, age, sex, hypertension, diabetes mellitus, smoking, territory of disease, degree of stenosis (70%–90% versus 90%–99%), type of stent used, and timing of the procedure (whether the procedure was done in first half of the study period or in the later half), was assessed and studied for impact on the various outcome measures.
Procedural success rate was 97.44% in our study. Technical failure because of the difficulty to negotiate the stent to the target lesion occurred in 2.56% (5 of 195) of the lesions. The incidence of all complications ≤1 month after the procedure was 9.74% (19 of 195 lesions; Table).
All strokes at 1 month were 11 (5.64%), of which 2 (1.02%) were major, both related to stent thrombosis not responding to tirofiban, and 9 (4.61%) were minor. Of the minor strokes, 5 were attributable to perforator occlusion because of the stent and 4 were embolic in the territory of the stented artery. The mortality at 1 month was 1.09% (2 of 182 patients). One patient died of a major stroke resulting from stent thrombosis and the other due to worsening of azotemia and severe hemothorax. There was acute (during or within 48 hours of the procedure) stent thrombosis in 5 stented lesions (2.56%). Of these, there was major stroke because of the failure to lyze the thrombus in 2 patients, as already mentioned, and 3 were asymptomatic as a result of successful lysis of the thrombus with tirofiban.
The incidence of periprocedural (1 month) complications was 12 of 19 (63.15%) in the first half of our study period (April 2004 to April 2008) and 7 of 19 (36.85%) in the second half (May 2008 to May 2012). The 1-month complication rate in anterior circulation lesions was 8.62% (10 complications in 116 lesions stented), and in posterior circulation lesions, it was 11.39% (9 complications in 79 lesions stented). The incidence of perforator territory stroke was maximum in the basilar artery lesions (4 strokes of the 39 lesions stented; ie, 10.25%). Only 1 perforator territory stroke occurred in all the other lesions put together (1 of the 156 lesions stented; ie, 0.56%).
Recurrent TIA or stroke occurring up to 1-year follow-up in the territory of the stented artery was encountered in 7 patients. Therefore, the 1-year incidence of all strokes or TIAs (including periprocedural) in this study is 18 (9.8%). All these 7 patients underwent a follow-up angiogram. Restenosis, defined as >20% absolute luminal loss, was found in 4 of these patients. All the symptomatic patients were advised to continue dual antiplatelets lifelong (online-only Data Supplement).
All the patients in our series had severe stenosis, which is described as >70% stenosis, a factor known to be associated with greater risk of stroke.2 The results of stenting versus aggressive medical management in intracranial stenosis trial were recently published. The 30-day rate of stroke or death in the stenting arm of the SAMMPRIS3 (Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis) trial was 14.6% compared with 5.8% in the medical management group. We had a 30-day stroke rate of 5.64% in our series, which is comparable to the early series in the literature.4–7
Procedural safety and success because of the rigidity of the device and high inflation pressures were of concern in balloon-expandable stents. In our series, predilation was avoided as far as possible (done only in 14 lesions) to reduce the chances of vessel dissection. Other technical modifications, such as marginal undersizing of the stent, slow optimal inflation of the stent at nominal, and in some cases, even subnominal, pressures and avoidance of postdilation also contributed to the safety of our procedure.
We used both driver (bare metal) and endeavor (drug eluting) stents (Figure 1), with a procedural success rate of 97.44%. Endeavor stent was preferred in long lesions (>5 mm), small target vessels (<2.75 mm), and in relatively younger patients. We did not find any difference in ease of navigating the stent to the target lesion between the driver (bare-metal stent) and endeavor (drug-eluting stent [DES]) groups. Comparatively, limited data are available in the literature on DES.8–11 To our knowledge, ours is one of the largest series in which DES are used in 87 lesions.
Perforator stroke attributable to the compromise of perforating arteries remains a challenge in intracranial atherosclerotic lesions. Perforator stroke occurs as a result of the snow plow effect. Lesions with extensive associated ostial disease were excluded from our series, which is one of the reasons for the low rate of perforator stroke (2.7%) in our series.12
In-stent thrombosis is another known complication with the use of intracranial stents. Five patients in our series had acute in-stent thrombosis, of whom 2 did not respond to intra-arterial tirofiban resulting in major strokes. In 3 patients, the thrombus dissolved on administration of tirofiban and there was no neurological deficit on extubation (Figure 2).
In-stent restenosis is defined as >20% absolute luminal loss and is another concern in determining the efficacy of an intracranial stenting procedure. One-year follow-up angiogram was performed in 66% of our patients, and 5.7% (7 lesions) of the lesions showed restenosis. Lack of angiographic follow-up in all patients is one of the limitations in our study, which is likely to underrepresent the rate of restenosis. However, clinical follow-up data are available on all patients, and recurrent TIA or stroke was encountered in 7 patients on follow-up, and 4 of these patients had restenosis on angiogram. In the long-term clinical follow-up (beyond 1 year) none of the patients had any recurrent symptoms in the stented vascular territory.
In their study of DES in 95 patients, Vajda et al11 described a restenosis rate of 3.8%. Kim et al13 described their experience in patients with intracranial atherosclerotic disease with >50% stenosis with intracranial stent implantation where endeavor was used in 46 patients with a restenosis rate of 4%. The lower restenosis rate in our series may be partially attributed to the use of DES as well as to the criteria based on which the stent placement was decided.
In the present post-SAMMPRIS era, the results of our study with 97.4% success rate, 5.6% stroke rate at 30-day interval, 9.8% stroke or TIA incidence at 1-year interval, and 5.7% restenosis at 1-year follow-up are encouraging. Debate still continues on the results of the SAMMPRIS trial, on whether the complications in the stenting arm were attributable to device issues, limited experience, poor patient selection, etc.11,14,15 Intracranial stenting with balloon-expandable intracranial stents is a safe and feasible method and should be considered as a therapeutic option in selected patients with severe symptomatic intracranial stenosis (>70%) refractory to medical therapy with an acceptable risk to benefit ratio.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.113.001446/-/DC1.
- Received March 12, 2013.
- Accepted March 19, 2013.
- © 2013 American Heart Association, Inc.
- Kasner SE,
- Chimowitz MI,
- Lynn MJ,
- Howlett-Smith H,
- Barney JS,
- Vicki SH,
- et al.
- 4.↵SSYLVIA Study Investigators. Stenting of symptomatic atherosclerotic lesions in the vertebral orintracranial arteries (SSYLVIA): study results. Stroke. 2004;35:1388–1392.
- Mazighi M,
- Yadav JS,
- Abou-Chebl A
- Jiang WJ,
- Wang YJ,
- Du B,
- Wang SX,
- Wang GH,
- Jin M,
- et al
- Abou-Chebl A,
- Bashir Q,
- Yadav JS
- Gupta R,
- Al-Ali F,
- Thomas AJ,
- Horowitz MB,
- Barrow T,
- Vora NA,
- et al
- Fields JD,
- Petersen BD,
- Lutsep HL,
- Nesbit GM,
- Liu KC,
- Dogan A,
- et al
- Michael P,
- Marks S