B Crandall

Pre-procedure P2Y12 reaction units value predicts perioperative thromboembolic and hemorrhagic complications in patients with cerebral aneurysms treated with the Pipeline Embolization Device

Background There is wide variability in the reported incidence of perioperative thromboembolic (0–14%) and hemorrhagic (0–11%) complications after Pipeline Embolization Device (PED) procedures for cerebral aneurysm treatment, which could be partly due to differences in patient response to the P2Y12 receptor antagonist administered while the PED endothelializes. This study aims to identify an optimal pre-procedure P2Y12 reaction units (PRU) value range and determine the independent predictors of perioperative thromboembolic and hemorrhagic complications after PED procedures. Methods We recorded patient and aneurysm characteristics, P2Y12 receptor antagonist administered, pre-procedure PRU value with VerifyNow, procedural variables and perioperative thromboembolic and hemorrhagic complications up to postoperative day 30 after PED procedures at our institution during an 8-month period. Perioperative complications were considered major if they caused a permanent disabling neurological deficit or death. Multivariate regression analysis was performed to identify independent predictors of perioperative complications in our cohort. Results Forty-four patients underwent 48 PED procedures at our institution during the study period. There were eight thromboembolic and hemorrhagic perioperative complications in our cohort (16.7%), four of which were major (8.3%). A pre-procedure PRU value of <60 or >240 (p=0.02) and a technically difficult procedure (p=0.04) were independent predictors of all perioperative complications. A pre-procedure PRU value of <60 or >240 (p=0.004) and a history of hypertension (p=0.03) were independent predictors of major perioperative complications. Conclusions In our cohort, a pre-procedure PRU value of <60 or >240 was the strongest independent predictor of all and major perioperative thromboembolic and hemorrhagic complications after PED procedures.

Last-Recorded P2Y12 Reaction Units Value Is Strongly Associated with Thromboembolic and Hemorrhagic Complications Occurring Up to 6 Months after Treatment in Patients with Cerebral Aneurysms Treated with the Pipeline Embolization Device

BACKGROUND AND PURPOSE: A recent study identified a preprocedural P2Y12 reaction units value of <60 or >240 as a strong independent predictor of perioperative thromboembolic and hemorrhagic complications after treatment of cerebral aneurysms with the Pipeline Embolization Device. This study aimed to determine whether a last-recorded P2Y12 reaction units value of <60 or >240 predicts thromboembolic and hemorrhagic complications up to 6 months after treatment of cerebral aneurysms with the Pipeline Embolization Device in the same patient cohort. MATERIALS AND METHODS: We recorded patient and aneurysm characteristics, P2Y12 receptor antagonist administered, P2Y12 reaction units value with VerifyNow, procedural variables, and thromboembolic and hemorrhagic complications up to 6 months after Pipeline Embolization Device procedures at our institution during an 8-month period. Complications causing a permanent disabling neurologic deficit or death were considered major. Multivariate regression analysis was performed to identify independent predictors of thromboembolic and hemorrhagic complications. RESULTS: Forty-four patients underwent 48 Pipeline Embolization Device procedures at our institution during the study period. There were 11 thromboembolic and hemorrhagic complications up to 6 months after treatment in our cohort (22.9%), 5 of which were major (10.4%). A last-recorded P2Y12 reaction units value of <60 or >240 was the only independent predictor of all (P = .002) and major (P = .03) thromboembolic and hemorrhagic complications in our cohort. Most patients (71%) required, on average, 2 adjustments to the dose or type of P2Y12 receptor antagonist to remain within the 60–240 target P2Y12 reaction units range. CONCLUSIONS: In our cohort, a last-recorded P2Y12 reaction units value of <60 or >240 was the only independent predictor of all and major thromboembolic and hemorrhagic complications up to 6 months after Pipeline Embolization Device procedures.

Variability in initial response to standard clopidogrel therapy, delayed conversion to clopidogrel hyper-response, and associated thromboembolic and hemorrhagic complications in patients undergoing endovascular treatment of unruptured cerebral aneurysms

Background and purpose Variability in response to clopidogrel therapy is increasingly being recognized as an important factor in thromboembolic and hemorrhagic complications encountered after neurointerventional procedures. This study aims to determine the variability in response to clopidogrel therapy and associated complications in patients undergoing endovascular treatment of unruptured cerebral aneurysms. Methods We recorded baseline patient characteristics, co-administered medications, P2Y12 reaction units (PRU) values with VerifyNow, clopidogrel dosing, and thromboembolic and hemorrhagic complications in patients undergoing endovascular treatment of unruptured cerebral aneurysms at our institution during a 19 month period. Results 100 patients were included in the study, 76 women and 24 men, mean age 57.3 years. 15 patients exhibited an initial clopidogrel hypo-response (PRU >240) and 21 patients an initial clopidogrel hyper-response (PRU <60). 36 patients had a follow-up VerifyNow test performed without changes to the standard 75 mg daily clopidogrel dose, which demonstrated that 59% of patients who had initially been within the target 60–240 PRU range exhibited a delayed conversion to clopidogrel hyper-response. In our cohort, a clopidogrel hypo-response was associated with a significantly increased risk of thromboembolic complications in patients undergoing cerebral aneurysm treatment with stent assistance or the pipeline embolization device (60%, p=0.003), while a clopidogrel hyper-response was associated with a significantly increased risk of major hemorrhagic complications in all patients undergoing endovascular treatment of cerebral aneurysms (11%, p=0.016). Conclusions We found wide and dynamic variability in response to clopidogrel therapy in patients undergoing endovascular treatment of unruptured cerebral aneurysms, which was significantly associated with thromboembolic and major hemorrhagic complications in our cohort.

Diagnostic Yield of Catheter Angiography in Patients with Subarachnoid Hemorrhage and Negative Initial Noninvasive Neurovascular Examinations

These authors explored the diagnostic yield of DSA in patients with SAH and previously negative CTA or MRA. A total of 55 patients who presented with diffuse SAH, perimesencephalic SAH, or sulcal SAH received CTA (n= 47) or MRA (n= 8). Despite normal findings on CTA or MRA, DSA showed vascular lesions in 11% of patients with diffuse SAH and in 1 patient with sulcal SAH. The investigators concluded that DSA is a valuable tool in patients with diffuse or sulcal SAH in whom previous noninvasive examinations are negative. BACKGROUND AND PURPOSE: The yield of DSA in patients with SAH and negative initial noninvasive neurovascular examinations (CTA or MRA) is not well-understood. This study aimed to determine the yield of DSA for the detection of causative vascular lesions in this clinical scenario. MATERIALS AND METHODS: We examined the yield of DSA for the detection of causative vascular lesions in a cohort of patients presenting to our institution with SAH and negative initial noninvasive neurovascular examinations during a 5-year period. Two experienced neuroradiologists independently evaluated the NCCT to determine the SAH pattern (diffuse, perimesencephalic, or peripheral sulcal) and the catheter angiograms to assess the presence of a causative vascular lesion. RESULTS: Fifty-five patients were included in the study, with a mean age of 58.2 years (median, 58 years; range, 25–88 years). Twenty-eight patients were men (50.9%), and 27 were women (49.1%). The initial noninvasive examination was a CTA in 47 patients (85.5%) and an MRA in 8 patients (14.5%). Thirty-three patients had diffuse SAH (60%); 11, perimesencephalic SAH (20%); and 11, peripheral sulcal SAH (20%). DSA demonstrated a causative vascular lesion in 6 patients (10.9%), 5 of whom had diffuse SAH (yield of 15.2%) and 1 of whom had peripheral sulcal SAH (yield of 9.1%). No causative vascular lesions were found in patients with perimesencephalic SAH. CONCLUSIONS: DSA is a valuable tool in the evaluation of patients with diffuse and peripheral sulcal SAH who have negative initial noninvasive neurovascular examinations, demonstrating a causative vascular lesion in 15.2% and 9.1% of patients, respectively.

Diagnostic yield of delayed neurovascular imaging in patients with subarachnoid hemorrhage, negative initial CT and catheter angiograms, and a negative 7 day repeat catheter angiogram

Purpose The yield of delayed neurovascular imaging in patients with subarachnoid hemorrhage (SAH), negative initial CT and catheter angiograms (CT angiography (CTA), DSA), and negative 7 day repeat DSA is not well understood. Our aim was to determine the yield of delayed neurovascular imaging for the detection of causative vascular lesions in this clinical scenario. Methods We retrospectively examined the yield of delayed CTA and DSA for the detection of causative vascular lesions in patients presenting to our institution with SAH, negative initial CTA and DSA examinations, and a negative 7 day repeat DSA during a 6.5 year period. Two neuroradiologists evaluated the non-contrast CTs to determine the SAH pattern, and the delayed CTAs and DSAs to assess for the presence of a causative vascular lesion. Results 39 patients were included: 23 men (59%) and 16 women (41%), mean age 55.5 years (range 33–75). 25 patients had diffuse SAH (64.1%), 12 had perimesencephalic SAH (30.8%), and two had peripheral sulcal SAH (5.1%). The delayed neurovascular examination was CTA in 30 patients (76.9%) and DSA in nine patients (23.1%). Mean time to delayed CTA or DSA was 34.9 days (median 34, range 14–69 days). Delayed CTA demonstrated a causative vascular lesion in two patients (5.1%, one small internal carotid artery aneurysm and one small pontine arteriovenous malformation), both with diffuse SAH (yield 8%). Conclusions Delayed neurovascular imaging is valuable in the evaluation of patients with diffuse SAH who have negative initial CTA and DSA examinations and a negative 7 day repeat DSA, demonstrating a causative vascular lesion in 8% of patients.

O-005 Frequency of Post-Procedural Diffusion Weighted Imaging Abnormalities and Association with Delayed Ipsilateral Intracerebral Haemorrhages in Patients Undergoing Endovascular Treatment of Cerebral Aneurysms with the Pipeline Embolization Device

Purpose To determine the frequency and predictors of post-procedural diffusion-weighted-imaging (DWI) abnormalities in patients with cerebral aneurysms treated with the Pipeline Embolization Device (PED). Methods Two interventional neuroradiologists reviewed post-procedural MRI examinations performed in patients with cerebral aneurysms treated with the PED at our institution to determine the number of DWI abnormalities present in the vascular territory of the treated aneurysm. Baseline patient and aneurysm characteristics and procedural variables were recorded. Results Twenty-two patients were included, 15 female (68%) and 7 male (32%), mean age 53.2 years (25–79 years). Mean aneurysm size 11.2 mm (2.5–22 mm), mean neck size 6.5 mm (1.6–17 mm), 5 aneurysms were fusiform (22.7%). Mean pre-procedure P2Y12 reaction units (PRU) value was 164.9 (81–275). PEDs were deployed in the internal carotid artery (ICA) in 16 patients (72.8%), middle cerebral artery in 3 patients (13.6%) and vertebral artery in 3 patients (13.6%). Mean procedure time was 86 min (median 75 min, range 39–189 min). Mean number of PEDs deployed was 1.2. At the time of post-procedural MRI, 4 patients exhibited focal neurological deficits (18%, mean 3.5 days post-procedure) and 18 were asymptomatic (82%, all on post-operative day [POD] 1). At least 1 DWI abnormality was observed in 17 patients (77%), including all 4 symptomatic (100%) and 13 asymptomatic patients (72%). Mean number of DWI abnormalities was 12.5 (median 4, range 0–70), with a trend towards a higher number in symptomatic patients (mean 26.8, range 5–70) than in asymptomatic patients (mean 9.3, range 0–48, p-value 0.1). Eleven patients had a high DWI burden, defined as ≥5 DWI abnormalities (50%). Predictors of a high DWI burden were fusiform aneurysm morphology (100%, p-value 0.035), female sex (67%, p-value 0.06), and procedure time >90 min (70%, p-value 0.09). Conclusion We observed a high rate of asymptomatic ipsilateral DWI abnormalities after PED procedures (72%). The combination of a high DWI burden and P2Y12-receptor over-inhibition post-procedure may play an important role in the aetiology of delayed ipsilateral ICHs encountered after PED procedures. Abstract O-005 Figure 1 Female patient undergoing urgent treatment of fusiform right ICA aneurysm on ticagrelor, procedure time 93 min, with high asymptomatic DWI burden (n = 48) and an asymptomatic ipsilateral intracerebral haemorrhage (ICH) identified in routine MRI on POD 1 (PRU 49 at time of asymptomatic ICH). On POD 4, after administration of 75 mg clopidogrel doses on POD 2 and 3, the patient developed severe headache, hemiparesis and hemianopsia with marked ICH enlargement and further P2Y12-receptor over-inhibition (PRU 8) Disclosures J. Delgado Almandoz: 2; C; Covidien/ev3. Y. Kadkhodayan: 2; C; Covidien/ev3. J. Fease: None. J. Scholz: None. A. Blem: None. K. Tran: None. B. Crandall: 2; C; Covidien/ev3.

E-052 Initial Institutional Experience with the Sceptre XC Balloon for the Endovascular Treatment of Cerebral Aneurysms

Background and purpose The Sceptre XC balloon is a novel extra-compliant dual-lumen balloon microcatheter designed for the endovascular treatment of cerebral aneurysms and arteriovenous malformations. This study aims to describe our initial institutional experience with the Sceptre XC balloon for the treatment of cerebral aneurysms. Methods We performed a retrospective review of endovascular treatments of cerebral aneurysms with the Sceptre XC balloon at our institution from April 11th, 2012 until February 28th, 2014. Baseline patient and aneurysm characteristics, procedural variables, packing density, intra- operative and post-operative complications, and clinical outcomes using the modified Rankin Scale (mRS) were recorded. Results Forty-five patients underwent endovascular treatment of 54 cerebral aneurysms with assistance of the Sceptre XC balloon at our institution during the study period, 33 females (73%) and 12 males (27%), mean age 58.5 years (28–87 years). Fifty-three aneurysms were treated successfully (98.1%). Forty-two aneurysms were unruptured (78%) and 12 ruptured (22%); 5 aneurysms were recurrent (9%). Mean aneurysm size was 7 mm (median 6.3 mm, range 2–17 mm), mean neck size was 3.2 mm (median 2.8 mm, range 1–8.2 mm), mean dome-to-neck ratio was 1.8 (median 1.5, range 0.8–6.5). Aneurysm locations were 17 middle cerebral artery (32%), 13 anterior communicating artery (24%), 13 internal carotid artery (24%), 5 posterior communicating artery (9%), 2 pericallosal artery (4%) and 4 posterior circulation (7%). Balloon neck remodeling was performed in 49 aneurysms (91%), and stent-assistance was ultimately used in 3 aneurysms (5.6%). Three aneurysms were coiled directly through the Sceptre XC balloon (5.6%). Mean packing density was 39.4% (median 40%, range 12–72.2%). Immediate complete/near complete occlusion was achieved in 34 aneurysms (64%), residual neck in 7 aneurysms (13%) and residual sac in 12 aneurysms (23%). The table summarises the intra-operative and post-operative complications in our cohort. There were 3 intra-operative aneurysm ruptures (5.6%), 2 of previously-ruptured aneurysms (16.7%) and 1 of an unruptured aneurysm (2.4%), hemostasis was achieved by immediate balloon inflation in all cases and no patient developed a new neurological deficit. There was 1 distal branch vessel rupture during balloon inflation performed to reduce an intra-aneurysmal catheter loop for a wire exchange prior to stenting, resulting in the patient’s death (2.2%). There was 1 ipsilateral intracerebral haemorrhage on post-operative day 2 in a hypertensive patient with a clopidogrel hyper-response leading to permanent contralateral hemiparesis (2.2%). Overall, 2 complications led to either a new permanent disabling neurological deficit or the patient’s death (mRS ≥ 3, 4.4%). Conclusion The Sceptre XC balloon is a valuable adjunctive device for the endovascular treatment of cerebral aneurysms, allowing high treatment success rates and packing densities, achievement of immediate hemostasis in the event of an intra-operative aneurysm rupture, and reduction in the overall need of stent-assistance for cerebral aneurysm treatment. Abstract E-052 Table 1 Intra-operative and post-operative complications Complication Number of occurrences Percent of aneurysms Complications resulting in new neurological deficit or death Percent of patients Intra-operative aneurysm rupture 3 5.6 0 Intra-operative distal vessel rupture 1 1.9 1 (death) 2.2 Any coil loop herniation into parent artery 7 13 1 (transient neurological deficit) 2.2 Coil loop herniation requiring stenting 1 1.9 0 Distal coil migration requiring coil retrieval 1 1.9 0 Post-operative ipsilateral infarction 1 1.9 1 (transient neurological deficit) 2.2 Post-operative ipsilateral intracerebral haemorrhage 1 1.9 1 (permanent hemiparesis) 2.2 Complications resulting in a new permanent disabling neurological deficit or death (mRS ≥ 3) 2 3.7 2 4.4 Disclosures J. Delgado Almandoz: 2; C; Microvention/Terumo, Covidien/ev3, Penumbra Inc. Y. Kadkhodayan: 2; C; Covidien/ev3. J. Fease: None. J. Scholz: None. A. Blem: None. K. Tran: None. B. Crandall: 2; C; Covidien/ev3.

P-006 Initial Response to Aspirin Therapy Measured with the PFA-100 Assay in Patients Undergoing Endovascular Treatment of Unruptured Cerebral Aneurysms

Background and purpose Recent studies have examined the variability in response to clopidogrel therapy in patients undergoing endovascular treatment of unruptured cerebral aneurysms; however, no study has systematically assessed patient response to aspirin therapy in this patient population. This study aims to determine the initial response to aspirin therapy in patients undergoing endovascular treatment of unruptured cerebral aneurysms. Methods We retrospectively reviewed the results of platelet function testing in a cohort of patients who were started on aspirin therapy for the endovascular treatment of unruptured cerebral aneurysms at our institution from November 17th, 2011 until March 13th, 2014. Baseline patient characteristics, aspirin dosing and thromboembolic complications were recorded. Patient response to aspirin therapy was assessed with the PFA-100 assay before the procedure, with ≥50% inhibition defined as an appropriate platelet response. Results One-hundred and seventeen patients were included in the study, 23 male (20%) and 94 female (80%), mean age 56 years (25–84 years). The patients included in this cohort comprised 52.5% of patients who underwent treatment of an unruptured cerebral aneurysm at our institution during the study period. Forty-eight patients were active smokers (41%), 72 had a history of hypertension (62%) and 6 diabetes mellitus (5%). Sixty-two patients were treated with simple or balloon-assisted coiling (53%), 43 with the Pipeline Embolization Device (37%) and 12 with a stent (10%). Fifty-three patients were started on 325 mg aspirin (45%), 50 on 81mg enteric-coated aspirin (43%), and 14 on 81 mg non-enteric-coated aspirin (12%). Mean number of aspirin doses before the initial PFA-100 test was 11.5 (median 9, range 3–29). Overall, mean initial platelet inhibition was 68.2% (median 70.5%, range 20.5–94.6%), with a significantly-lower mean inhibition in patients taking 81mg enteric-coated aspirin (62.5%) compared to those taking 81 mg non-enteric-coated aspirin (72.1%, p-value 0.049) and 325 mg aspirin (72.5%, p-value 0.001). Overall, 13 patients were considered to be non-responders to aspirin therapy in the initial PFA-100 test (11.1%), most of whom were taking 81mg enteric-coated aspirin (9, 69%). There was a significantly-increased likelihood of an initial non-response to aspirin therapy among patients taking 81 mg enteric-coated aspirin (18%) compared to those taking 81 mg non-enteric-coated aspirin (7.1%) and 325 mg aspirin (5.7%, p-value 0.04). In multivariate logistic regression analysis, an 81 mg enteric-coated aspirin dose was the only independent predictor of an initial non-response to aspirin therapy in our cohort (odds ratio 0.52, 95% confidence interval 0.28–0.98, p-value 0.043). There were 7 thromboembolic complications in our cohort (6%), none of which caused a permanent disabling neurological deficit or death. All of the patients who experienced a thromboembolic complication had demonstrated an appropriate platelet response to aspirin therapy in pre-procedure testing. Conclusion Performing pre-procedure platelet function testing in patients taking 81 mg enteric-coated aspirin to ensure an adequate platelet response to aspirin therapy may be prudent prior to undertaking endovascular treatment of an unruptured cerebral aneurysm. Disclosures J. Delgado Almandoz: 2; C; Covidien/ev3, Microvention/Terumo. Y. Kadkhodayan: 2; C; Covidien/ev3. J. Scholz: None. J. Fease: None. A. Blem: None. K. Tran: None. B. Crandall: 2; C; Covidien/ev3.

E-065 Medium-Term Clinical Outcome of Patients with Aneurysmal Subarachnoid Haemorrhage Treated Endovascularly within the Framework of a Multi-Disciplinary Neurovascular Team at a Tertiary Referral Medical Centre over a 45-Month Period

Purpose To determine the medium-term clinical outcome in a cohort of patients presenting with aneurysmal subarachnoid haemorrhage (SAH) treated endovascularly within the framework of a multi-disciplinary neurovascular team at a tertiary referral medical centre over a 45-month period. Methods We conducted a retrospective review of all patients who presented to our institution with aneurysmal SAH and underwent endovascular treatment of the ruptured aneurysm within the framework of a multi-disciplinary neurovascular team from January 1st, 2009, until September 30th, 2012. Baseline clinical characteristics, surgical and endovascular interventions performed and discharge disposition were recorded. Clinical outcome at the time of last follow-up was assessed with the modified Rankin Scale (mRS). A good clinical outcome was defined as an mRS 0–2. Results One-hundred and twenty-four patients presented with aneurysmal SAH and underwent endovascular treatment of the ruptured aneurysm at our institution during the study period. Eighty-seven patients were female (70.2%) and 37 male (29.8%), with a mean age of 56.2 years (median 57 years, range 22–91 years). Sixty-eight patients required placement of an external ventricular drain (54.8%), 28 placement of a ventriculoperitoneal shunt (22.6%), and 6 a decompressive craniectomy (4.8%). Twenty-six patients required endovascular treatment of symptomatic cerebral vasospasm (21%), 85% of which were treated with balloon-angioplasty of the affected vessel (s) with or without an intra-arterial nicardipine infusion, and 15% were treated with an intra-arterial nicardipine infusion only. Mean Neuro-ICU length of stay was 14.3 days (median 14.5 days, range 1–39 days). Mean hospital length of stay was 19 days (median 18 days, range 1–39 days). Discharge disposition was home in 62 patients (50%), a rehabilitation facility in 39 patients (31.5%), a skilled nursing facility in 12 patients (9.7%), and 11 patients did not survive the hospitalisation (8.9%). Eight patients were lost to follow-up (6.5%). Mean time to last clinical follow-up for the 105 survivors with follow-up was 14.6 months (median 9.6 months, range 3.7–48 months). Overall, a good clinical outcome at the time of last clinical follow-up was observed in 83 patients (71.6%). The table summarises the clinical outcome at the time of last clinical follow-up according to admission Hunt-Hess scale in our patient cohort. Conclusion The majority (72%) of patients presenting with aneurysmal SAH who underwent endovascular treatment of the ruptured aneurysm within the framework of a multi-disciplinary neurovascular team at our institution demonstrated a good clinical outcome at the time of last clinical follow-up, including 41% of patients with an admission Hunt-Hess scale 4–5. Clinical Outcome at the Time of Last Clinical Follow-up in Patients with Aneurysmal SAH Abstract E-065 Table 1 All patients: Admission Hunt-Hess 1-2: Admission Hunt-Hess 3: Admission Hunt-Hess 4-5: p-value: All patients: 116 (100%) 50 (43.1%) 32 (27.6%) 34 (29.3%) mRS 0-2: 83 (71.6%) 47 (94%) 22 (68.8%) 14 (41.2%) mRS 3: 13 (11.2%) 1 (2%) 4 (12.5%) 8 (23.5%) mRS 4-5: 7 (6%) 0 2 (6.3%) 5 (14.7%) mRS 6: 13 (11.2%) 2 (4%) 4 (12.5%) 7 (20.6%) <0.0001 Disclosures J. Delgado Almandoz: 2; C; Covidien/ev3. Y. Kadkhodayan: None. B. Crandall: 2; C; Covidien/ev3. J. Scholz: None. R. Anderson: None. K. Lockhart: None. T. Mowbray-Donahue: None. K. Uittenbogaard: None. G. Dyste: None. J. Fease: None. D. Tubman: 2; C; Covidien/ev3, MicroVention.

E-064 ASPECTS ≥5 on Non-Contrast CT and CT Angiography Source Images Predicts Clinical Outcome in a Cohort of 30 Patients Undergoing Mechanical Thrombectomy with Stent-Retrievers

Purpose To determine if the Alberta Stroke Program Early CT Score (ASPECTS) applied to non-contrast CT (NCCT) and CT angiography source images (CTA-SI) predicts clinical outcome in a cohort of patients with an acute middle cerebral artery (MCA) occlusion undergoing mechanical thrombectomy with stent-retrievers. Methods We conducted a retrospective review of patients who presented to our institution with an acute MCA occlusion and underwent mechanical thrombectomy with a stent-retriever from March 31st, 2012 until February 21st, 2013. Baseline clinical and procedural characteristics were recorded. Two experienced neurointerventionalists applied the ASPECTS to the pre-treatment NCCT and CTA-SI (if performed), with differences resolved by consensus. A “good scan” was defined as one with an ASPECTS ≥5. Clinical outcome at the time of hospital discharge or last clinical follow-up was determined utilising the modified Rankin Scale (mRS), with a good clinical outcome defined as an mRS of 0–2. Results Thirty patients presented to our institution with an acute MCA occlusion and underwent mechanical thrombectomy with a stent-retriever during the study period. Fifteen patients were female (50%) and 15 male (50%), with a mean age of 67.2 years (median 69 years, range 33–86 years). Mean admission NIHSS was 15.8 (median 16, range 5–27). Sixteen patients (53.3%) had received iv-tPA prior to endovascular treatment. Twenty-five patients (83.3%) had an MCA M1 segment occlusion and in 5 patients (16.7%) the occlusion extended to the internal carotid artery terminus. Mean time from NCCT to arterial puncture was 117 minutes (median 109 minutes, range 39–307 minutes). Mean time from CTA to arterial puncture was 104 minutes (median 92 minutes, range 16–272 minutes). Successful recanalisation (TICI 2b/3) was achieved in 26 patients (86.7%). Mean time from arterial puncture to successful recanalisation was 47 minutes (median 37 minutes, range 18–115 minutes). Mean time from symptom onset to successful recanalisation was 333 minutes (median 285 minutes, range 125–893 minutes). All pre-treatment NCCTs were categorised as “good scans”, with perfect inter-observer agreement. Twenty patients had a pre-treatment CTA performed (66.7%), 11 of which were categorised as “good scans” (55%), with substantial inter-observer agreement (kappa 0.8). Overall, a good clinical outcome was observed in 11 patients (36.7%), with a statistically-significant difference between the 12 patients age ≤65 years (66.7%) and the 18 patients age >65 years (16.7%, p-value 0.009). The table summarises the frequency of a good clinical outcome according to age group and pre-treatment CTA-SI ASPECTS. Conclusion In our cohort of patients with acute MCA occlusion undergoing mechanical thrombectomy with stent-retrievers, a “good scan” NCCT (ASPECTS ≥5) predicted a 67% likelihood of a good clinical outcome in patients age ≤65 years, while a “good scan” CTA (ASPECTS ≥5) predicted a 43% likelihood of a good clinical outcome in patients age >65 years. Clinical Outcome after Mechanical Thrombectomy with Stent-Retrievers by Age and CTA-SI ASPECTS. Abstract E-064 Table 1 All patients: ≤65 years: >65 years: p-value: CTA-SI ASPECTS: 0-4 5-10 0-4 5-10 0-4 5-10 N: 9 11 5 4 4 7 mRS 0–2: 1 7 1 4 0 3 mRS 3–6: 8 4 4 0 4 4 % mRS 0–2: 11.1 63.6 20 100 0 42.9 0.023 Disclosures J. Delgado Almandoz: 2; C; Covidien/ev3. Y. Kadkhodayan: None. M. Young: None. B. Crandall: 2; C; Covidien/ev3. R. Tarrel: None. J. Fease: None. J. Scholz: None. R. Anderson: None. T. Hehr: None. K. Gozel: None. R. Shronts: None. D. Tubman: 2; C; Covidien/ev3.