Abstract TMP7: Not All mTICI 2b Are Made Equal: Balancing the Risks and Benefits of the Ideal Reperfusion Target in Endovascular Stroke Therapy

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Introduction: The standard reperfusion target for thrombectomy trials has been modified TICI (mTICI) 2b-3 (≥50% ischemic territory). Recently, full reperfusion (mTICI 2c-3) has been recommended as the ideal target. The potential added benefits of additional procedural maneuvers must be balanced against their risks, particularly when dealing with residual distal occlusions often found in mTICI 2b. It remains unknown whether more precise categorization of the mTICI2b strata leads to more reasonable treatment targets. Methods: Retrospective analysis of prospectively collected thrombectomy data spanning Jun 2011-Feb 2018. Inclusion criteria: MCA and intracranial internal carotid artery occlusions. Definitions of reperfusion: mTICI0-1: no or limiteddistal filling; mTICI2a: <50% of territory; mTICI2b-: 50-74% of territory; mTICI2b+: 75-99%; mTICI3: full. Results: Of 557 patients, 2.2% had mTICI0-1, 3.6% had mTICI2a, 5.9% had mTICI2b-, 30.2% mTICI2b+, and 58.2% mTICI3. The usage of intravenous tPA was lower in the mTICI2b- vs. mTICI3 (18% vs. 41%;p<0.01) patients but otherwise there were no differences in baseline characteristics (age, gender, hypertension, diabetes, atrial fibrillation, NIHSS, occlusion site). Parenchymal hematomas were comparable between groups. The rates of good outcome (90-day mRS0-2) were comparable between mTICI3 vs mTICI2b+ (52% vs 46%;p=0.2) but were significantly lower in the mTICI2b- (30%;p=0.02), mTICI2a (5%; p<0.001) and mTICI0-1 (9%;p=0.003) groups (mTICI 3 as reference) ( Figure ). Mortality rates were comparable across the mTICI2b-, mTICI 2b+, and mTICI 3 groups but higher with mTICI2a (40%;p=0.01) and mTICI0-1 (50%;p<0.01) vs mTICI3 (16%). Conclusion: There is broad variation in outcomes across the different degrees of reperfusion within the mTICI 2b grade. A reperfusion target of 75%-99% (mTICI2b+) may lead comparable rates of independence versus full reperfusion.