Yield of ASPECTS and Collateral CTA Selection for Mechanical Thrombectomy within 6-24 hours from Symptom Onset in a Hub and Spoke System.

BACKGROUND: Recent extended window trials support the benefit of mechanical thrombectomy in anterior circulation large vessel occlusions with clinical-radiographic dissociation. Using trial imaging criteria, 6% were found eligible for MT in the EW in a hub-and-spoke system. We examined the eligibility and outcomes in consecutive extended window-mechanical thrombectomy patients using more pragmatic selection criteria. METHODS: We retrospectively analyzed single-institution data of anterior circulation large vessel occlusions patients presenting between 6-24 h who underwent mechanical thrombectomy based on a priori determined criteria including non-contrast CT head ASPECTS ≥ 6 and/or CTA collateral scores ASITN/SIR 2-4. Primary outcomes consisted of post-mechanical thrombectomy TICI 2b-3 and 3-month modified Rankin scores; safety outcomes consisted of in-hospital mortality and symptomatic intracerebral hemorrhage. RESULTS: 767 consecutive acute ischemic strokes patients presented within the 6-24 hour window, and of these 48 (6%) anterior circulation large vessel occlusions patients underwent mechanical thrombectomy. In this cohort the mean age was 63±17 years, 56% were male, the median NIHSS was 16 [IQR 10-19], the median ASPECTS was 9 (IQR 8-10), and 79% (n=38) had good CTA collaterals. Occlusions were primarily M1 MCA (46%), with 29% tandem occlusions. Successful recanalization (mTICI 2b or 3) was achieved in 73% (n=35), while 6% (n=3) of patients developed symptomatic intracerebral hemorrhage. In-hospital mortality was 25% (n=12) while 40% (n=19) achieved 3-month modified Rankin Scores 0-2. CONCLUSIONS: Our data suggest the use of pragmatic imaging approach of ASPECTS ≥6 with CTA collateral grade in extended time window which is already established in most hospitals.