Abstract 016: Natural evolution of incomplete reperfusion after endovascular therapy: systematic review and meta‐analysis

Introduction Despite recent advances in endovascular therapy, up to half of acute ischemic stroke patients experience incomplete reperfusion (expanded Thrombolysis in Cerebral Infarction, eTICI<3) after intervention. However, many of these patients will achieve complete delayed reperfusion at the 24h follow‐up, which is linked to good clinical outcome and minimal new infarct development. We aimed to systematically review literature and perform a meta‐analysis on the natural evolution of incomplete reperfusion after endovascular therapy. Methods We conducted a systematic review of MEDLINE, Embase and PubMed up until March 1, 2024 using a predefined search strategy. Only full‐text English written articles reporting rates of either favorable (i.e. delayed reperfusion) or unfavorable progression (i.e. persistent perfusion deficit) of incompletely reperfused tissue were included. Primary outcome was the rates of delayed reperfusion 24h post‐intervention and its association with functional independence (modified Rankin Scale, mRS 0‐2) at 90 days post‐intervention. Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using a random‐effects model. Publication bias was assessed using funnel plots and the Luis Furuya‐Kanamori (LFK) index. Results Six studies involving 950 patients (50.7% female; median age 71, IQR 60 ‐ 79) were included. Four studies assessed the evolution of incomplete reperfusion on MRI perfusion imaging, while two studies used DWI and NCCT imaging, where new infarct was used to denote unfavorable progression. Complete delayed reperfusion, or absence of new infarct, occurred in 41% (inter‐quartile range, IQR 33% ‐ 51%) of cases 24h post‐intervention. Achieving delayed reperfusion was associated with higher likelihood of functional independence at 90 days (OR 2.53, 95%CI 1.88 ‐ 3.42). No evidence of publication bias was found (LFK=0.2). Conclusion Nearly half of patients with incomplete reperfusion achieve complete delayed reperfusion, leading to favorable clinical outcomes. This subgroup of eTICI<3 patients may derive limited or potentially harmful effects from pursuing additional reperfusion strategies (e.g. intra‐arterial lytics or secondary distal thrombectomy). Accurately predicting the progression of incomplete reperfusion could optimize patient selection for adjunctive reperfusion attempts at the end of an intervention.