Abstract WP12: Downstream Clot Fragment Migration During Endovascular Clot Extraction Adversely Affects Clinical Outcome

Background and Purpose: FDA approval of endovascular clot extraction devices that are used in stroke is based on efficacy for opening target arteries safely. Favorable clinical outcomes using devices currently available, however, is limited. Time to treat and stroke severity are obvious contributors, but a factor that receives little attention is intraoperative downstream migration of clot fragments. We assessed the effect of migrated clot fragments on clinical outcome in patients treated at our institution. Methods: With IRB approval, we retrospectively reviewed charts, procedure reports, and images of all patients with M1 occlusions treated with endovascular clot extraction within the past 5 years to compare relevant variables and discharge outcomes in patients whose arteries were ultimately “open” (OP) versus “open with fragments” (OF). Results: Thirty four patients were treated (21 Penumbra, 7 Merci retriever, 6 Solitaire), all under general anesthesia. Numbers of patients in each category of final vessel patency were: OP=15, OF=19. No significant intergroup differences were found (means) for age (60), gender (male 55%), time from onset to treatment (4.71 hours), admission BP (141/82), duration of anesthesia (2.1 hrs), mean blood pressure during anesthesia (132/70), admission NIHSS (13.8), pretreatment with IV-rtPA (70%). OP patients were more likely to have had an atheroembolic than cardiac source of stroke (p<0.03), as well as treatment with Solitaire stent (all 6 Solitaire patients were OP). OF were more likely to have had IV-rtPA (p<0.15), treatment with Penumbra (p<0.03), and adjunctive use of IA-rtPA and abciximab for target clot (p<0.09). OP had lower discharge NIHSS (6.79 v 13.22; p<.03); greater change in NIHSS (-6.21 v -1.89; p<0.03); discharge mRS=0-2 (47% v 21%; p<0.15); discharge mRS=0-3 (53% v 79%; p<0.005); discharged home (33% v 11%; p<0.2). There was one death in each group (NS), one sICH in OF, and length of stay was 8 days in both. Conclusion: Although our numbers are small, they strongly suggest an adverse effect of downstream clot fragments on outcomes. Awareness of this phenomenon should be useful in the approval process for future devices, as well as in the evaluation of post-marketing device use.