Contrary to what we hypothesized, the results of this trial showed that aggressive medical therapy was superior to PTAS with the use of the Wing-span system in high-risk patients with intracranial stenosis, because the rate of periprocedural stroke after PTAS was higher than expected and the rate of stroke in the medical-management group was lower than estimated. The 30-day rate of stroke or death in the PTAS group (14.7%) is substantially higher than the rates previously reported with the use of the Wingspan stent in the phase I trial and in two registries (rates ranging from 4.4% to 9.6%).10,20,25
The higher rate in the current study does not reflect inexperience of the operators, because most of the interventionists who participated in the registries also participated in this trial, and all the interventionists in this trial were credentialed to participate on the basis of evidence of their experience. In addition, the rates of periprocedural stroke did not decline over the course of the enrollment period and did not differ significantly between high-enrolling sites and low-enrolling sites in this trial.
One possible explanation for the higher rate of periprocedural stroke in this trial as compared with the registries is that all the patients in this study had stenosis of 70 to 99% and recent symptoms, whereas the registries included patients with stenosis of 50 to 99% and symptoms that had occurred more than 30 days before enrollment. Recent symptoms may be a marker for unstable plaque, which could increase the risk of distal embolism during stenting, as has been reported with extracranial carotid stenting.26,27
Another explanation for the higher rate of periprocedural stroke in this trial is that the rigorous protocol for evaluating events (i.e., evaluation of all potential end points by neurologists, the adjudication process, and site-monitoring visits) could have resulted in the detection of some milder strokes that may not have been detected in the registries. However, the percentage of primary end-point strokes in the PTAS group that were disabling or fatal (35%; 16 of 46 patients) is higher than the percentage of primary end-point strokes that were categorized as major in the stenting group (21%) or the endarterectomy group (28%) in a recent randomized trial involving patients with extracranial carotid stenosis.28
The rate of stroke in the medical-management group was much lower than expected. Patients in the WASID trial with the same entry criteria who were treated with aspirin or warfarin and standard management of risk factors had a 30-day rate of stroke or death of 10.7% and a 1-year rate of the primary end point of 25%.10
In contrast, the corresponding rates in the medical-management group in this trial were 5.8% and 12.2%. Although we expected the rate of stroke to be reduced with intensive management of risk factors — on the basis of post hoc analyses from the WASID trial that suggested that lowering LDL cholesterol and systolic blood pressure could reduce the risk of stroke22,29
— we were surprised at the extent and rapidity of the reduction. It is also possible that the combination of aspirin and clopidogrel played an important role in lowering the early risk of stroke. This is supported by the results of a study of transcranial Doppler ultrasonography involving patients with recently symptomatic intracranial stenosis, which showed that aspirin and clopidogrel, as compared with aspirin alone, reduced the frequency of ipsilateral distal microemboli.30
The effect of the lifestyle modification program on the outcome can be determined only at the end of the follow-up period, but it is unlikely that it contributed to a reduction in the risk of stroke in the medical-management group within 30 days after enrollment.
The difference between the treatment groups in the rate of the primary end point is driven by the early events, since the rates of the primary end point beyond 30 days are currently similar in the two groups. However, fewer than half the patients have been followed for longer than 1 year. Therefore, continued follow-up of the patients who are currently enrolled will be important to determine the long-term outcome in the two groups. Among patients who are receiving medical management only, progression of stenosis may occur over time that could result in a stroke from a distal embolism or hypoperfusion.31-35
Among patients in whom a stent has been placed, restenosis occurs in 25 to 30% within 6 months after intracranial PTAS36,37
and could also lead to later stroke.
Patients with symptoms that occurred more than 30 days before enrollment or with stenosis of 50 to 69% of an intracranial artery were excluded from this trial because their risk of stroke while receiving standard medical care is relatively low (approximately 3 to 9% at 1 year 8,21
), making it unlikely that they would benefit from PTAS. These patients could have an even lower risk of stroke if they received aggressive medical therapy. This trial did not evaluate angioplasty alone or other devices (e.g., balloon-mounted stents) that are used off-label to treat patients with intracranial stenosis. Although these devices may have benefits over the Wingspan system (e.g., single-step delivery and deployment of the stent and less residual stenosis after the procedure), none have been compared with medical management.
The current results of this trial indicate that medical therapy as delivered in this trial is superior to PTAS with the Wingspan stent system, which is associated with a high risk of periprocedural stroke or death in this population. Although not all the components of the aggressive medical regimen used in this trial may be easy to duplicate in clinical practice, essential elements can readily be adopted, including adding clopidogrel to aspirin for the first 90 days and following the trial’s protocol with respect to lowering blood pressure and LDL cholesterol in order to achieve target levels that are based on national guidelines.38,39