The conventional method to prevent ischaemic stroke is medical therapy, including oral anti-platelet therapy and medication to control risk factors for intracranial atherosclerosis such as hypertension, hyperglycaemia and hyperlipidaemia. However, for patients with severe intracranial stenosis to an extent of over 70%, the risk of stroke is 23% every year, despite being treated with medical therapy. There is currently no effective treatment for intracranial stenosis. Narrowed vessels cannot be widened with medical therapy. The feasibility of bypass surgery for narrowed vessels is 20%, and bypass surgery is not better than medical therapy in stroke prevention.
Supported by a research fund from ‘Vascular and Interventional Radiology Foundation’, a clinical study on ‘Intracranial Stenting (Wingspan) for Prevention of Ischaemic Stroke’ led by Professor Simon Chun Ho Yu, Professor Lawrence Ka Sing Wong and Professor Thomas Wai Hong Leung, has been carried out jointly in The Vascular and Interventional Radiology Foundation Clinical Science Centre, Department of Imaging and Interventional Radiology and Division of Neurology of Department of Medicine and Therapeutics at The Chinese University of Hong Kong (CUHK) since 2006. The aim of the study was to evaluate the safety and effectiveness of the treatment. Intracranial angioplasty and stenting with Wingspan have been performed for 93 patients who have intracranial stenosis with minor ischaemic stroke or symptoms of cerebral ischaemia despite being treated with medical therapy, including 69 men and 24 women, with and average age of 65 (range 34 to 84). The patients were followed for an average of 36 months.
It was found that the success rate of stenting procedure was 95.7%. Death or stroke rate within 30 days of the treatment was 5.4%, lower than that observed in international studies (9.6%); in-stent restenosis rate was 13.6% within 12 months; and the risk of stroke after treatment was 6.1% per year, much lower than that observed in patients treated by medical therapy alone (23%). The magnitude of this study in terms of number of patients from a single centre is significant by a global standard, making it valuable for evaluation of the treatment.
The study showed that stenting and angioplasty with Wingspan is safe and effective for prevention of stroke, particularly for patients with severe intracranial stenosis (>70%) and with minor ischaemic stroke or symptoms of cerebral ischaemia despite being treated with medical therapy. Relevant articles of the study have been published in the journals American Journal of Neuroradiology (April 2011) and Neurosurgery (August 2011).
In conclusion, the emergence of intracranial angioplasty and stenting therefore offers a new hope for patients with severe intracranial atherosclerosis. Although the procedure of stenting itself carries a death or stroke risk of 5.4%, the risk is still relatively much more acceptable compared to the annual stroke risk of 23% with medical therapy alone. Based on the study, the investigators recommend the following:
(1) Patients at high risk of ischaemic stroke should consider to receive stenting for stroke prevention, specifically those presented with symptomatic minor ischemia stroke or transient ischemic attack despite medical therapy, and those with degree of intracranial stenosis was ≥ 70% for patients, and those with the diameter of vessel ≥2mm;
(2) If the patients decide to receive stenting, their doctors-in-charge should consider to refer their patients to experienced centres for the treatment as the procedure is still risky. Procedure safety is closely related to the experience of the operating team;
(3) The government should consider to subsidize the treatment cost. Currently the cost of the stent and related consumables is HKD 45,000 and patients who need the treatment have to bear the cost in most of the public hospitals. Successful prevention of stroke will not only allow the patients and their families to avoid pain and suffering from the disease, but it will also allow saving of much resources in hospitalization, rehabilitation and disability caring.