Symptomatic Vertebrobasilar Disease Research Articles

Intervention for symptomatic vertebrobasilar disease.

Disease of the vertebral (VA) and basilar arteries (BA) can lead to stroke of the posterior circulation and may warrant management strategies which differ from the anterior circulation. The mechanism and location of the disease determine its natural history and therefore affect the relative risks and benefits of the possible treatment options. Vertebrobasilar (VB) atherosclerotic disease is a source of both hemodynamic and embolic posterior circulation stroke. Advances in medical therapy have decreased the rate of stroke after initial symptomatic presentation. Antiplatelet therapy, blood pressure control, and optimization of secondary risk factors can reduce recurrent stroke risk in both intracranial and extracranial VB disease. However, symptomatic intracranial disease is still associated with a high risk of subsequent stroke, particularly those with hemodynamic compromise who represent a higher risk population. Patients with hemodynamic impairment may benefit from judicious application of endovascular and microsurgical interventions to augment blood flow. Stenting, angioplasty alone, bypass surgery, and endarterectomy, represent endovascular and surgical tools available to address medically refractory VB disease. Apart from atherosclerotic disease, dissection is another etiology of VB stroke, most frequently affecting the extracranial VA. Treatment is predominantly antithrombotic therapy although surgical or endovascular intervention can be required in rare cases of persistent embolism or hemodynamic compromise. In contrast, extrinsic compromise of the VA represents a separate extracranial pathology and is best treated with mechanistically targeted surgeries or extracranial bypass.

Poor Risk Factor Control And Lower Levels Of Physical Activity Predict Incident Major Cardiovascular Events In Patients With Symptomatic Vertebrobasilar Disease: A Post-hoc Analysis Of The SAMMPRIS Trial (926)

Poor Risk Factor Control And Lower Levels Of Physical Activity Predict Incident Major Cardiovascular Events In Patients With Symptomatic Vertebrobasilar Disease: A Post-hoc Analysis Of The SAMMPRIS Trial (926)

Abstract WMP47: Poor Risk Factor Control and Lower Levels of Physical Activity Predict Incident Major Cardiovascular Events in Patients With Symptomatic Vertebrobasilar Disease: A Post-Hoc Analysis of the SAMMPRIS Trial

Background: Symptomatic vertebrobasilar (VB) atherosclerotic disease is associated with a high risk of recurrent stroke despite optimal medical therapy. Objective: In this study, we aim to examine the prognosis and associations between risk factors and recurrent major cardiovascular events (MACE) in patients with symptomatic VB stenosis randomized in the medical arm of the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) study. Methods: Data from subjects in the medical arm of the SAMMPRIS trial with an infarct in the territory of vertebral or basilar arteries (n= 73) were analyzed. The primary outcome was MACE: defined as stroke, myocardial infarction, or other cardiovascular death during follow up. Mean risk factor values were compared between subjects who met the primary outcome at 2 years versus those who did not, using T-tests and χ2 tests. Results: Among 73 patients with VB stenosis randomized to medical treatment, 18 patients (24.6%) had recurrent MACE over a mean follow up of 2.8 years. This was significantly less than the rate of MACE in those with VB enrolled in the WASID trial (9.7 per 100-patient years vs. 20.9 per 100-patient years, p<0.01). Predictors of MACE at 2 years were increased triglyceride level (adjusted OR per 50 units increase in triglyceride 1.94, 95% CI 1.15-3.28) and increased HbA1c level (adjusted OR per 1 unit increase in HbA1c 2.07, 95% CI 0.97-4.45), and lower physical activity status measured by PACE (out of target defined by PACE ≤ 4: moderate activity < 5 days per week or intense activity < 3 days per week) (2.5 ± 1.0 vs. 3.3 ± 1.8, p = 0.028) (Table). Conclusions: In patients with symptomatic VB disease, improvement of medical treatment over time led to a reduction in cardiovascular event rates but this risk remains elevated as nearly 1 in 5 patients had MACE within 2 years. Further risk factor optimization and lifestyle changes are needed to reduce the rates of MACE in this patient population.

Abstract TP112: Mechanism of Recurrent Stroke in Patients with Atherosclerotic Vertebrobasilar Disease in Relation to Hemodynamics

Objectives: Patients with symptomatic atherosclerotic vertebrobasilar disease are at high risk for recurrent stroke and we have demonstrated that distal flow status is independently associated with this risk. Our aim was to assess the mechanism of recurrent strokes in these patients related to their distal flow status. Methods: Patients with symptomatic atherosclerotic vertebrobasilar disease were enrolled in a prospective longitudinal cohort study (VERiTAS) with a median follow-up of 23 months. Large-vessel flow in the posterior circulation distal to the stenosis and/or occlusion was measured on quantitative MR angiography and dichotomized into normal or low flow. Three observers, who were blinded to the distal flow status, independently reviewed the imaging done at the time of the recurrent stroke to classify the most likely stroke mechanism. Results: Ten out of 72 enrolled patients had a recurrent stroke in the posterior circulation. Four patients were determined to have embolic infarcts, four patients had infarcts caused by plaques that occluded a branch or perforating artery (junctional plaques), and two patients had imaging that suggested hemodynamic infarction. Five of the ten patients with recurrent strokes had low distal flow. Of these, two patients had hemodynamic infarcts, one patient had an embolic infarct, and two patients had a junctional plaque. None of the five patients with normal flow had hemodynamic infarcts, three patients had embolic infarcts, and two patients had a junctional plaque. Conclusion: Despite the small numbers, there seems to be a higher risk of hemodynamic infarction in patients with low flow distal to symptomatic vertebrobasilar disease than in the presence of normal distal flow. This would confirm the hypothesis that in addition to embolic strokes and those related to junctional plaque, patients with low distal flow are at risk for hemodynamic infarction. Further studies are required to determine whether flow measurements could be used to select patients who may benefit from endovascular treatment of atherosclerotic vertebrobasilar disease.

Vertebrobasilar Flow Evaluation and Risk of Transient Ischaemic Attack and Stroke Study (Veritas): Rationale and Design

Over one-third of ischaemic strokes occur in the posterior circulation, and a leading cause is atherosclerotic vertebrobasilar disease. Symptomatic vertebrobasilar disease carries a high annual recurrent stroke risk, averaging 10-15% per year. Endovascular angioplasty and stenting are increasingly used but carry risks, and the benefit remains unproven. Determining stroke predictors in this population is critical to identifying high-risk patients for future trials of intervention. Preliminary studies indicate that stroke risk in vertebrobasilar disease is strongly related to haemodynamic compromise, which can be measured noninvasively using quantitative magnetic resonance angiography. The Vertebrobasilar Flow Evaluation and Risk of Transient Ischaemic Attack and Stroke (VERiTAS) study, a prospective multicentre NIH-funded observational study of symptomatic vertebrobasilar stenosis (≥50%) or occlusion, is designed to test the hypothesis that patients demonstrating compromised blood flow as assessed by quantitative magnetic resonance angiography are at higher stroke risk. The study will recruit 80 patients at six sites in North America over 4-years. Upon enrollment, subjects will undergo haemodynamic assessment with blinded quantitative magnetic resonance angiography to assess large vessel flow in the vertebrobasilar territory, and be prospectively designated as compromised or normal flow. Patients will be re-imaged with quantitative magnetic resonance angiography at 6-, 12-, and 24-months, and followed for 12-24-months for the primary end-point of stroke in the vertebrobasilar territory. The VERiTAS study is the first prospective study of haemodynamics and stroke risk in the posterior circulation. The results may impact the selection criteria for interventional candidates and also define a low-risk population in whom the risks of invasive interventions would be unnecessary.

Use of Quantitative Magnetic Resonance Angiography to Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Use of Quantitative Magnetic Resonance Angiography to Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Use of Quantitative Magnetic Resonance Angiography to Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Conclusion: Quantitative magnetic resonance angiography (QMRA) can stratify risk for stroke in patients with symptomatic vertebrobasilar disease (VBD). Summary: Phase-contrast QMRA is a magnetic resonance technique for noninvasively measuring blood flow in intracranial vessels (Magn Reson Imaging 2000;18:697-706). The authors used a standard protocol that included QMRA to evaluate patients with symptomatic VBD. QMRA was used to stratify patients according to the presence or absence of flow compromise distal to the site of VBD. Flow was considered compromised in specific vessels if it was reduced greater than 20% of the lower limit of normal baseline value for that vessel. Flow compromise was evaluated in the basilar and posterior cerebral arteries. The basilar artery was designated as having reduced flow if flow measurements were less than 12 mL/min, and the posterior cerebral arteries were designated as having reduced flow if flow measurements were less than 40 mL/min. Patients with low distal flows were then offered either surgical or endovascular intervention, and other patients received standard medical therapy. The article reports the results of this protocol for patients treated from 1998 to 2003. There were 50 patients subjected to the protocol and 47 available for follow-up over a mean interval of 28 months. Kaplan-Meier curves were used to calculate stroke and stroke-free survival at 2 years and a combination of stroke-free survival and freedom from transient ischemic attacks at 2 years. Patients with normal distal flow (n = 31) had event-free survivals of 100% and 96%, respectively. At 2 years patients with low distal flows had a 71% event-free survival with respect to stroke and a 53% event-free survival with respect to the combined end point of stroke and transient ischemic attack. Patients with low distal flows had a higher risk of recurrent ischemia (P = .003). Twelve patients with low flow underwent treatment and had 82% event-free survival. With Cox proportional analysis, flow status effected event-free survival independently of covariants. Comment: Patients with symptomatic VBD can be offered intervention for large-vessel stenoses that are believed to be hemodynamically significant. However, collateralization in the posterior circulation can be extensive, and the presence of hemodynamically significant lesions in the proximal vessels does not necessarily result in diminished posterior circulation blood flow. QMRA may provide a method of selection for intervention for those patients with VBD who are most likely to benefit from an open or endovascular surgical procedure. This article may represent a major step forward for the selection of patients for vertebral artery reconstruction.

Use of Quantitative Magnetic Resonance Angiography To Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Use of Quantitative Magnetic Resonance Angiography To Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Use of Quantitative Magnetic Resonance Angiography to Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Symptomatic vertebrobasilar disease (VBD) carries a high risk of recurrent stroke. We sought to determine whether a management algorithm consisting of quantitative hemodynamic assessment could stratify stroke risk and guide the need for intervention. All patients with symptomatic VBD at our institution are evaluated by a standard protocol including quantitative magnetic resonance angiography (QMRA). Patients are stratified on the basis of the presence or absence of distal flow compromise. Those with low distal flow are offered intervention (surgical or endovascular); all patients receive standard medical therapy. We reviewed the clinical outcome of patients managed with this protocol from 1998 to 2003. Follow-up was available for 47 of 50 patients over a mean interval of 28 months. Stroke and combined stroke/transient ischemic attack free survival at 2 years was calculated using the Kaplan-Meier curve. Patients with normal distal flow (n=31) had an event-free survival of 100% and 96%, respectively. Comparatively, patients with low distal flow (n=16) experienced a 71% and 53% event-free survival, demonstrating a significantly higher risk of recurrent ischemia (P=0.003). Patients with low flow who subsequently underwent treatment (n=12) had an 82% event-free survival. Cox proportional hazards analysis demonstrated that flow status affected event-free survival regardless of covariates. Patients with symptomatic VBD demonstrating low distal flow on QMRA appear to have a high risk of stroke; conversely, those with normal flow seem to have a benign course and may be optimally managed with medical therapy alone.

Use of Quantitative Magnetic Resonance Angiography to Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Background and Purpose— Symptomatic vertebrobasilar disease (VBD) carries a high risk of recurrent stroke. We sought to determine whether a management algorithm consisting of quantitative hemodynamic assessment could stratify stroke risk and guide the need for intervention. Methods— All patients with symptomatic VBD at our institution are evaluated by a standard protocol including quantitative magnetic resonance angiography (QMRA). Patients are stratified on the basis of the presence or absence of distal flow compromise. Those with low distal flow are offered intervention (surgical or endovascular); all patients receive standard medical therapy. We reviewed the clinical outcome of patients managed with this protocol from 1998 to 2003. Results— Follow-up was available for 47 of 50 patients over a mean interval of 28 months. Stroke and combined stroke/transient ischemic attack free survival at 2 years was calculated using the Kaplan–Meier curve. Patients with normal distal flow (n=31) had an event-free surv...