Surgical Indirect Revascularization For Symptomatic Intracranial Arterial Stenosis

Intracranial arterial atherosclerosis is a significant medical problem, with elevated rates of recurrent stroke despite medical therapy, with annual recurrence rates for ischemic stroke reported in the SAMMPRIS Trial as high as 12.2% in the intensive medical therapy arm. The incidence of recurrence stroke can be even higher in some high-risk groups, as high as 25% in African-Americans and females. The ultimate goal of this project is to advance a promising surgical treatment for symptomatic atherosclerotic intracranial stenosis - encephaloduroarteriosynangiosis (EDAS). Compared with direct revascularization operations (bypass), EDAS has the advantages of being less technically demanding, avoiding temporary occlusion of cerebral vessels, and allowing gradual development of collateral circulation where the brain demands it, deterring early hyperperfusion and hemorrhage. There has been no systematic trial exploring the use of EDAS in cases of symptomatic, non-moyamoya intracranial arterial stenosis. Based on preliminary positive results, the investigators propose the long-term objective of demonstrating that EDAS improves the outcome in patients with symptomatic intracranial stenosis compared with aggressive medical therapy. This will require future phase III clinical trials. The present proposal has the purpose of testing in a phase II futility-design trial the potential of EDAS for further development before proceeding with the design of a definitive clinical trial of EDAS Revascularization in patients with Symptomatic Intracranial Arterial Stenosis (ERSIAS). The present project will be 4-year futility-design trial to determine if EDAS revascularization combined with aggressive medical therapy warrants further evaluation in a subsequent pivotal trial as an alternative to aggressive medical management alone for preventing the primary endpoint of stroke or death at two years in patients with symptomatic intracranial arterial stenosis (Specific Aim 1). During the investigation the investigators will systematically evaluate the time course of collateralogenesis and perfusion improvement following EDAS by using quantitative and semiquantitative perfusion MRI studies (Specific Aim 2). The new knowledge generated by this study on understanding the role of collateral circulation in stroke pathophysiology, patient selection, and use of non-invasive imaging will be useful not only for EDAS evaluation but potentially next generation stents and future novel medical therapies, such as use of angiogenic growth factors and/or endothelial stem cells.

Inclusion criteria

• TIA or non-severe stroke within 30 days of enrollment attributed to 70% to 99% stenosis* of a major intracranial artery (carotid artery or MCA)

*May be diagnosed by TCD, MRA, or CTA to qualify, but must be confirmed by catheter angiography as per usual clinical practice.

• Modified Rankin scale score of ≤3
• Target area of stenosis in an intracranial artery that has a normal diameter of 2.00 mm to 4.50 mm
• Target area of stenosis is ≤14 mm in length
• Age ≥30 years and ≤80 years

• Patients 30 to 49 years of age are required to meet at least 1 additional criteria (i-vi) provided below to qualify for the study. This additional requirement is to increase the likelihood that the symptomatic intracranial stenosis in patients 30 to 49 years is atherosclerotic: i. Insulin-dependent diabetes for at least 15 years ii. At least 2 of the following atherosclerotic risk factors: hypertension (BP ≥ 140/90 mm Hg or on antihypertensive therapy); dyslipidemia (LDL ≥130 mg/dL or HDL ≤40 mg/dL or fasting triglycerides ≥150 mg/dL or on lipid lowering therapy); smoking; non-insulin-dependent diabetes or insulin-dependent diabetes of <15 years duration; family history of any of the following: myocardial infarction, coronary artery bypass, coronary angioplasty or stenting, stroke, carotid endarterectomy or stenting, and peripheral vascular surgery in parent or sibling who was < 55 years of age for men or < 65 for women at the time of the event.

iii. History of any of the following: myocardial infarction, coronary artery bypass, coronary angioplasty or stenting, carotid endarterectomy or stenting, or peripheral vascular surgery for atherosclerotic disease iv. Any stenosis of an extracranial carotid or vertebral artery, another intracranial artery, subclavian artery, coronary artery, iliac or femoral artery, other lower or upper extremity artery, mesenteric artery, or renal artery that was documented by noninvasive vascular imaging or catheter angiography and is considered atherosclerotic v. Aortic arch atheroma documented by noninvasive vascular imaging or catheter angiography vi. Any aortic aneurysm documented by noninvasive vascular imaging or catheter angiography that is considered atherosclerotic

• Negative pregnancy test in a female who has had any menses in the last 18 months
• Patient is willing and able to return for all follow-up visits required by the protocol.
• Patient is available by phone.
• Patient understands the purpose and requirements of the study, can make him/herself understood, and has provided informed consent.
• Demonstration of poor or no collateral flow in the territory of the qualifying stenotic vessel (ASITN/SIR Collateral Flow Grades 0-2) and hypoperfusion of the vascular territory in MRI.

Exclusion criteria

• Tandem extracranial or intracranial stenosis (70-99%) or occlusion that is proximal or distal to the target intracranial lesion
• Bilateral intracranial vertebral artery stenosis of 70% to 99% and uncertainty about which artery is symptomatic (e.g., if patient has pontine, midbrain, or temporal occipital symptoms)
• Stenting, angioplasty, or endarterectomy of an extracranial (carotid or vertebral artery) or intracranial artery within 30 days before the expected enrollment date
• Previous treatment of target lesion with a stent, angioplasty, or other mechanical device, or plan to perform staged angioplasty followed by stenting of target lesion
• Plan to perform concomitant angioplasty or stenting of an extracranial vessel tandem to an intracranial stenosis
• Presence of intraluminal thrombus proximal to or at the target lesion
• Any aneurysm proximal to or distal to the stenotic intracranial artery
• Intracranial tumor (including meningioma) or any intracranial vascular malformation
• Computed tomographic or angiographic evidence of severe calcification at target lesion
• Thrombolytic therapy within 24 hours before enrollment
• Progressive neurologic signs within 24 hours before enrollment
• Brain infarct within previous 30 days of enrollment that is of sufficient size (> 5 cm) to be at risk of hemorrhagic conversion during or after surgery
• Any hemorrhagic infarct within 14 days before enrollment
• Any hemorrhagic infarct within 15 to 30 days that is associated with mass effect
• Any history of a primary intracerebral (parenchymal) hemorrhage
• Any other intracranial hemorrhage (subarachnoid, subdural, or epidural) within 30 days
• Any untreated chronic subdural hematoma >5 mm in thickness
• Intracranial arterial stenosis related to arterial dissection, Moya-Moya disease; any known vasculitic disease; herpes zoster, varicella zoster or other viral vasculopathy; neurosyphilis; any other intracranial infection; any intracranial stenosis associated with cerebrospinal fluid pleocytosis; radiation-induced vasculopathy; fibromuscular dysplasia; sickle cell disease; neurofibromatosis; benign angiopathy of central nervous system; postpartum angiopathy; suspected vasospastic process, and suspected recanalized embolus
• Presence of any of the following unequivocal cardiac sources of embolism: chronic or paroxysmal atrial fibrillation, mitral stenosis, mechanical valve, endocarditis, intracardiac clot or vegetation, myocardial infarction within 3 months, dilated cardiomyopathy, left atrial spontaneous echo contrast, ejection fraction <30%
• Known allergy or contraindication to aspirin and local or general anesthesia
• History of life-threatening allergy to contrast dye. If not life-threatening and can be effectively pretreated, patient can be enrolled at physician's discretion
• Known absolute contraindication to obtaining MRI studies, such as magnetically activated implanted devices (cardiac pacemakers, insulin pumps, neuro-stimulators, and cochlear implants), MRI incompatible orthopedic implants, and free metallic fragments in the brain or eye.
• Active peptic ulcer disease, major systemic hemorrhage within 30 days, active bleeding diathesis, platelets <100,000, hematocrit <30, INR >1.5, clotting factor abnormality that increases the risk of bleeding, current alcohol or substance abuse, uncontrolled severe hypertension (systolic BP>180 mm Hg or diastolic BP>115 mm Hg), severe liver impairment (AST or ALT > 3 times normal, cirrhosis), creatinine > 3.0 (unless on dialysis)
• Major surgery (including open femoral, aortic, or carotid surgery) within previous 30 days or planned in the next 90 days after enrollment
• Indication for warfarin or heparin beyond enrollment (NOTE: Exceptions allowed for use of subcutaneous heparin for deep venous thrombosis prophylaxis while hospitalized)
• Severe neurologic deficit that renders the patient incapable of living independently
• Dementia or psychiatric problem that prevents the patient from following an outpatient program reliably
• Comorbid conditions that may limit survival to < 3 years
• Females who are pregnant or of childbearing potential and unwilling to use contraception for the duration of this study
• Enrollment in another study that would conflict with the current study

Surgical Specific Exclusion Criteria:

In addition to those enumerated above, given the surgical nature of the intervention for patients failing best medical therapy, the following are additional exclusion criteria:

• Use of clopidogrel or extended release dipyridamole within 7 days of the date of surgery. This exclusion is based on the elevated risk of hemorrhagic complications for intracranial surgery using those agents according to the current AHA/ACC Guidelines (Fleisher et al., 2007).
• Evidence of active, un-treated focal or systemic infections (i.e. pneumonia, urinary tract infection, skin abscess) or history of recurrent infections despite treatment in the last 6 months.
• Coagulation disorders characterized by a PTT ≥ 34, or a PT ≥ 12, or an INR ≥ 1.3, or a platelet count of <80,000.
• Non-controlled hyperglycemia (any pre-prandial glucose level ≥ 180 mg/dL in any single test within 30 days before enrollment) or a hemoglobin A1c (HbA1c) ≥7%.
• A low-density lipoprotein cholesterol (LDL-c) ≥ 130 mg/dL.
• A non-high-density lipoprotein cholesterol (non-HDL-c) ≥ 100 mg/dL.
• Smoking history in the last 6 months.
• BMI ≥ 30 kg/m2