Intracranial Atherosclerosis: To Stent or Not to Stent?
June 1, 2008 4 minutes read
Intracranial Atherosclerosis: To Stent or Not to Stent?
Abstract & Commentary
By Dana Leifer, MD Associate Professor, Clinical Neurology, Weill Medical College, Cornell University. Dr. Leifer reports that she receives grant/research support from Neurobiological Technologies and ImaRx, and is on the speaker's bureau for Bristol-Myers Squibb and Sanofi Aventis.
Synopsis: Stenting is a possible option for the treatment of intracranial stenosis, but its safety and efficacy require further study in a randomized trial.
Source: Zaidat OO, et al. The NIH registry on use of the Wingspan stent for symptomatic 70-99% intracranial arterial stenosis. Neurology 2008;70:1518-1524.
Intracranial atherosclerosis is an important cause of ischemic stroke. It accounts for 8-10% of strokes in the United States and a higher percentage in other parts of the world. The Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial showed that symptomatic patients with 70-99% intracranial artery stenosis had an 18% risk of stroke within one year, in the territory of the stenosis, when treated medically. There was no significant difference in stroke risk between treatment with aspirin or with warfarin. Moreover, patients who were enrolled within 30 days of their qualifying event had a 23% risk of stroke within a year in the territory of the stenosis. The high rate of recurrent stroke in these patients indicates that better treatments are needed for symptomatic intracranial stenosis.
Angioplasty and stenting are now available as options for some patients with intracranial stenoses, but the efficacy of these approaches has not been tested adequately. Angioplasty, alone, has been problematic because of the high rates of residual stenosis and of restenosis. Stenting has been performed in a growing number of patients, but until recently most procedures were performed with stents designed for the coronary arteries. Coronary stents were stiff and difficult to place in intracranial arteries that are more tortuous and fragile than the coronary arteries. Recently, the Wingspan stent (Boston Scientific), which was designed for intracranial use, has been approved by the Food and Drug Administration under a humanitarian device exemption license for patients who remain symptomatic after maximum medical therapy.
Zaidat et al have now reported the initial results of treatment of symptomatic patients with >70% intracranial stenosis in 129 patients at 16 centers that participated in an NIH-sponsored registry. Patients were excluded if two stents were used for tandem stenoses or if stenting was performed in the setting of acute ischemic stroke. All patients were started on aspirin (81 to 325 mg/d) and clopidogrel (75 mg/d) prior to stenting and both drugs were continued for 4-12 weeks after stenting.
The procedures were considered technically successful, with a residual stenosis less than 50% at the end of the procedure in 96.7% of patients. Mean prestenting stenosis was 82%, and the mean stenosis immediately after stenting was 20%.
The primary endpoint for the study was the rate of any stroke or death within 30 days or a stroke in the territory of the stented artery at 6 months, for patients stented within 30 days of their qualifying event. There was a 14% risk of the primary endpoint in the entire group. Further analysis showed that the results were similar to those of the WASID trial for the first 3 months and then they diverged, because the number of events increased among medically managed patients in WASID but leveled off in stented patients. The rate of events increased to only about 16% after a year of follow-up among stented patients, but increased to 26% among medically treated patients in WASID. The results of this preliminary trial are encouraging, but the numbers are small, there was no control group, and there was no significant difference when compared to historical controls from the WASID trial.
Further analysis showed that results were better at centers that enrolled more patients; there was a 23% risk of recurrent stroke or death at the 10 sites that enrolled 1-8 patients and a 9% risk at the other 6 sites that enrolled 14-19 patients (p=0.02). This observation suggests that, for intracranial stenting, as for many other technical procedures, experience leads to better outcomes. On the other hand, the high enrolling sites tended to enroll patients with less severe stenoses (80% vs. 86%, p=0.004).
Commentary
The results of this registry suggest that intracranial stenting can be successfully performed in appropriate patients and that it may be considered as therapy for patients with symptomatic intracranial stenosis who have failed medical therapy. Further study in a randomized controlled clinical trial will be needed to compare the efficacy of stenting to that of optimal medical management. Such a trial is now being organized with support from the NIH. Until that trial is completed, intracranial stenting should be reserved for a select group of patients who have failed maximum medical therapy and who have a vascular anatomy that would allow safe placement of an intracranial stent by an experienced operator.
Stenting is a possible option for the treatment of intracranial stenosis, but its safety and efficacy require further study in a randomized trial.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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