Introduction: Mechanical thrombectomy (MT) for management of acute ischemic stroke (AIS) is widely accepted as efficacious but has been predominately utilized in patients with high NIHSS. For this reason, there remains limited published data for MT in patients admitted with NIHSS=/<10. We present the largest single-institution analysis to date of procedural and functional outcomes in our seven-year experience with MT in this population.

Methods: A retrospective analysis of our stroke database identified patients who underwent MT for AIS between 2010 and 2017. All patients were treated at Thomas Jefferson University. NIHSS on admission, intravenous tPA administration, occluded vessel, revascularization results, and functional outcomes on discharge were collected.

Results: In 310 patients, 59 (19.0%) presented with an admission NIHSS=/<10. Of this subgroup, median NIHSS on arrival was 8+/-2.3 and 31 patients (52.5%) received IV tPA prior to MT. The majority had MCA occlusions (67.8%), second most common were ICA (18.6%). Successful recanalization (TICI=2b-3) was achieved in 48 patients (81.4%), Nine patients (15.2%) had poor revascularization outcomes (TICI=1-2a), and two patients (3.4%) had failed recanalization (TICI=0). 55.6 % of patients with NIHSS=/<10 had a favorable outcome at discharge (mRS=0-3) compared to 38.6% of patients with NIHSS>10 (p=.015). Mortality between these two groups was not significantly different (10.2% vs. 12.4% p=.642).

Conclusions: Mechanical thrombectomy for AIS in patients admitted with NIHSS=/<10 has high rates of vessel recanalization and produces positive functional outcomes. A higher percentage of patients with NIHSS=/<10 are discharged with a favorable outcome compared to equivalently treated patients with NIHSS>10. Our results are in line with the few previously published reports examining MT in patients with low NIHSS, strengthening the argument that MT should be more regularly considered in this patient population.

Patient Care: Our study is an important contribution to the small body of evidence demonstrating the effectiveness of mechanical thrombectomy in patients with low NIHSS on admission. It is our hope that through presenting this data, mechanical thrombectomy becomes more widely used and studied in this patient population.

Learning Objectives: 1) Appreciate the high rates of positive surgical and functional outcomes that result from MT in AIS patients with NIHSS=/<10. 2) Identify how the results in our single-institution study compare to the existing literature. 3) Help the treating physician expand the options available for management of these patients.

References: 1. Bhogal P, Bucke P, Ganslandt O, et al. Mechanical thrombectomy in patients with M1 occlusion and NIHSS score =/<5: a single-centre experience. Stroke and Vascular Neurology 2016;1:e000052. 2. Pfaff J, Herweh C, Pham M, et al. Mechanical thrombectomy in patients with acute ischemic stroke and lower NIHSS scores: recanalization rates, periprocedural complications, and clinical outcomes. Am J Neuroradiol 37:2066-71