Intracranial Middle Cerebral Artery Percutaneous Intervention Using a Drug-Eluting Stent

Introduction

Intracranial angioplasty and stenting are increasingly being used to treat patients with recurrent cerebral ischemia due to intracranial atherosclerosis, which is a cause of 8-10% of all ischemic strokes. Since there are no commercially available stents designed specifically for the cerebral vasculature, all such procedures have utilized conventional coronary stenting systems. However, the incidence of stent restenosis in the intracranial circulation can be up to 40%.¹ Since the FDA approval of the Cypher™ sirolimus-eluting stent (Cordis Corporation, Miami, Florida) on April 24, 2003, it has rapidly become the dominant coronary stent in use today in the United States. By the end of 2003, approximately 350,000 patients in the US had received a Cypher stent, representing about half of all coronary stents used.² Its popularity is due to its marked reduction of restenosis. The only reported use of drug-eluting stents in intracranial vessels was in canine models.¹ We report the first human use of a Cypher stent during percutaneous intervention of an intracranial stenosis in the middle cerebral artery (MCA).

Case Report

A 43-year-old Caucasian female with hyperlipidemia, hypertension, and a twenty pack-year history of smoking presented seven months earlier with an infarct involving the right parietal lobe. Noninvasive imaging with transcranial Doppler (TCD) ultrasound showed elevated velocities in the right MCA (192 cm/s). Cerebral angiography showed a diffuse diffuse 80% distal right internal carotid artery (RICA) stenosis at the terminus extending into the MCA trunk to its bifurcation into the superior and inferior divisions. The patient was treated with aspirin and atorvastatin, and advised to quit smoking. However, two weeks following angiography, she had another small right MCA territory stroke. Repeat TCD demonstrated an increase in the mean flow velocities in the right MCA to 258 cm/s with impaired cerebrovascular reserve on breath holding. Repeat angiography showed worsening of the MCA stenosis, which had also developed irregular margins. Due to the rapid progression of the stenosis and the decreased cerebrovascular reserve, she underwent angioplasty and stenting following pretreatment with clopidogrel for five days. A 5F diagnostic JR4 catheter was advanced into the right external carotid artery over a floppy angled Glidewire using roadmapping guidance. The angled Glidewire was then exchanged for a stiff 6cm tip Amplatz wire, followed by removal of the JR4 catheter. An 8F 70cm Rabbe sheath was then advanced into the distal right common carotid artery. A 6F Envoy guide was telescoped through the Rabbe sheath and advanced to the petrous portion of the RICA. A long Synchro 0.014inch wire (with over-the-wire support of a 2.0X9-mm Maverick balloon) was then used to cross the distal RICA into the right MCA, and positioned in the distal M2 superior division. Predilatation of the right M1 segment was performed using the Maverick balloon, which resulted in some plaque shift into the origin of the inferior division. A second Synchro wire was advanced into the inferior division with the intention of dilating the origin. However, this origin stenosis was alleviated with wire crossing, thus, balloon dilatation was not required. We then proceeded to advance an over-the-wire 2.5X8-mm Cypher stent to the M1 stenosis. This was done with moderate difficulty since the Synchro wire is a soft wire, and there was tortuosity in the distal ICA. We were able to deliver the stent to the origin of the superior M2 division, and started initial deployment at 5 atmospheres. The stent balloon was then pulled back proximally by 3mm and re-inflated to 8 atmospheres. Excellent result was obtained with improved flow into the distal right MCA territory, without evidence of embolization or perforation. The patient tolerated the procedure well and remained in hospital overnight with aggressive systolic blood pressure control between 90 to 120 mmHg. A TCD was performed following the procedure, showing a reduction in velocity of the right MCA to 175 cm/s. She was discharged the following day in good condition on aspirin, clopidogrel, atorvastatin and metoprolol. She returned for follow-up angiography at 30 days which showed the stented segment to be widely patent. At two months follow-up, she remains well with no new symptoms since stent placement, and the TCD velocities were stable.

Discussion

This is the first human report of drug-eluting stent use during percutaneous intervention of an intracranial stenosis. The patient tolerated the procedure well, did not develop any neurological deficits, and was discharged home the following day. At 30-day follow-up, repeat angiography demonstrated wide patency of the stent. In this case, the Cypher stent was chosen over other more easily deliverable stents because of the rapid progression of the stenosis, the small caliber of the MCA, and the young age. Although no trial has been done to evaluate the safety and feasibility of a drug-eluting stent in the intracranial circulation, it is conceivable that the beneficial effect on restenosis seen in coronary arteries will also be seen within the intracranial vessels. The management of patients with significant intracranial atherosclerosis remains controversial. However, given the high stroke risk (10-24% per year) particularly among symptomatic patients, many practitioners advocate endovascular angioplasty/stenting, especially for patients who are refractory to maximal medical therapy (recurrent ischemic events while on therapeutic doses of antiplatelet or anticoagulant therapy).³ The use of a stent is considered superior to angioplasty alone for intracranial interventions because of the lower risk of abrupt closure, restenosis, dissection and recoil.⁴ However, stent delivery may be particularly challenging for the intracranial circulation due to the tortuosity of the internal carotid artery siphon, with technical success rate between 86-95%.^{4, 5} The use of bare-metal stents in the intracranial circulation is still associated with a relatively high restenosis rate. In the SSYLVIA (Stenting of Symptomatic Atherosclerotic Lesions in the Vertebral or Intracranial Arteries) study, among 43 patients who had intracranial arteries stented with the Neurolink system (Guidant Corp., Santa Clara, CA), 6-month angiographic restenosis (>50%) occurred in 32.4% of patients.⁵ Although the use of drug-eluting stents has not been studied for the intracranial circulation, the landmark randomized-controlled SIRIUS study showed a dramatic 91% reduction of in-stent restenosis with Cypher stent use in the coronary circulation.⁶ In a canine study by Levy et al, among 8 mongrels randomized to receive sirolimus-coated stents in the basilar artery, no neurotoxic effects were observed in explanted intracranial vessel walls or brainstem tissues.1 Furthermore, sirolimus-coated stents were shown to reduce smooth-muscle cell proliferation compared to bare-metal stents in these animals.¹ In summary, in this novel case report, we demonstrated the feasibility and safety of using a sirolimus drug-eluting stent for intracranial MCA stenosis. Randomized trials of drug-eluting stents for the intracranial circulation with long-term follow-up are warranted.