Abstract WP182: Re-Analysis of Stenting versus Aggressive Medical Therapy for Intracranial Arterial Stenosis (SAMMPRIS) Trial Using the New Food and Drug Administration (FDA) 'On Label' Criteria

Background: Due to higher rates of 1-month stroke and death with Wingspan intracranial stent placement observed in SAMMPRIS, FDA announced a more limited indication for Wingspan stent. We compared the results of intracranial stent placement with best medical treatment in patients who met “on label” criteria with those who were treated as “off label”. Methods: Patients recruited in the SAMMPRIS trial were classified as “on label” if: age 22 to 80 years, stenosis of 70%-99%, baseline modified Rankin Scale score ≤ 3, ≥2 ischemic events in the vascular territory of the stenotic lesion with at least 1 ischemic event while on medical therapy, and stent placement ≥8 days after the last stroke. All other patients were classified as “off label”. The primary endpoint was any stroke or death occurring within 30 days of enrollment, or any stroke or death within 30 days of any revascularization procedure of the qualifying symptomatic intracranial artery done during follow-up, OR an ischemic stroke in the territory of the symptomatic intracranial artery from day 31 after study entry to completion of follow-up. Results: A total of 31 (6.87%) among 451 recruited patients met the “on label” criteria. The relative risk of primary endpoint was lower in “on label” patients treated with stent placement compared with best medical treatment (RR 0.8, 95 % CI 0.2 - 2.9) but higher in “off label” patients (RR 1.65, 95 % CI 1.0-2.4). Primary endpoint was seen in 20% and 23.4% of patients treated with stent placement in “on label” and “off label” patients, respectively. Primary endpoint was seen in 25% and 14.2% of patients treated with best medical treatment in “on label” and “off label” patients, respectively. In Cox Proportional Hazards analysis with primary endpoint as dependent variable, the interaction between “on label” and treatment (stent versus best medical treatment) was not significant (p=0.6713). Conclusion: The new FDA “on label” criteria may identify a group of who may benefit from intracranial stent placement due to higher risk of primary endpoint in those treated with best medical treatment. However, the criteria appears to be very stringent and only a small proportion of patients may meet the “on label” criteria.