Table 2.
Relevant data regarding the eight published articles retained for the present systematic review, stratified by the number of excluded potential alternative causes for post-thrombectomy hypoperfusion (i.e., ICA stenosis, intracranial reocclusion, areas with hemorrhage). Note that no study excluded only one of these alternative causes.
| First author, year | N patients/onset-to-recanalization time (median[IQR] min) | Type of study | TICI classification used | Post-MT perfusion imaging timing/method | Definition of hypoperfusion | Exclusion of ICA stenosis | Exclusion of intracranial reocclusion | Exclusion of areas with hemorrhage | N (%) of m/eTICI2c patients with hypoperfusion | N (%) of new-m/eTICI3 patients with hypoperfusion | Impact on clinical outcome |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Studies excluding 3/3 potential alternative causes for hypoperfusion | |||||||||||
| ter Schiphorst, 2021/202320,33*$ | 33/196 [154–230]& | Retrospective | mTICI including 2c | 24hr/MRI ASL/GE Healthcare | Visual assessment in the initially occluded artery territory | Yes | Yes | Yes§ | 3/22 (13.6%) | 1/11 (9.1%) | No¤ |
| Luijten, 2023 32 $ | 27/107[61–367]@ | Patients from randomized controlled trial | mTICI including 2c | 24hr/MRI-ASL | ≥40% decrease in post-MT CBF in affected hemisphere compared to mirror region | Yes | Yes | YesΔ | 0/9 (0%) | 0/18 (0%) | Not assessable |
| Studies excluding 2/3 potential alternative causes for hypoperfusion | |||||||||||
| Ng, 2022 24 | 130/≤270& | Patients from randomized controlled trial | eTICI | 24hr/CTP or PWI/RAPID | Visual assessment of CBV and CBF maps within infarct, confirmed by >15% decrease vs mirror region | Yes | Yes | Only for quantitative analysis¥ | 15/73 (20.5%) | 18/57 (31.6%) | Yes across eTICI2c and eTICI3 |
| Mujanovic, 2022 26 | 338/169[88–376]# | Retrospective | eTICI | ≈24hr/CTP or PWI/Olea Sphere | Presence of Tmax ≥4 sec deficit within the initially occluded artery territory | Not specified | Yes | Yes∞ | 25/144 (17%) | 0/194 (0%) | Yes in eTICI2c patients; not assessable in eTICI3 |
| Studies excluding 0/3 potential alternative causes for hypoperfusion (or not mentioning them) | |||||||||||
| Potreck, 2021 22 | 29/248 [125–343] | Retrospective | mTICI including 2c | 24hr/PWI/Olea Sphere | Visual assessment within the infarct on CBF maps | No | No | No | 3/13 (23.1%)£ | 2/16 (12.5%)£ | No |
| Tan, 2021 23 | 31/282 [216–390] | Retrospective | mTICI including 2c | 24-36hr/CTP or PWI/RAPID | <90% reduction of pre-MT Tmax > 6s lesion volume in the affected hemisphere | No | No | Not specified | 3/15 (20%) | 3/16 (18.8%) | Not reported |
| Laredo 2022 25 $ | 12/≤1440 | Placebo group patients from randomized controlled trial | eTICI | 48hr/PWI/ MIStar | Presence of imaging deficit Tmax > 6sec outside or within the infarct | Not specified | Not specified | Not specified | 3/5 (60%) | 3/7 (42.9%) | Not reported |
| Hong, 2023 30 $ | 36/≤1440 | Retrospective | mTICI including 2c | 24-48hr/CTP/ MIStar | DT > 3 sec reperfusion index < 0.9 | No | Not specified | Not specified | 2/6 (33.3%) | 10/30 (33.3%) | Not reported |
*: The data for this study were extracted from two successive publications, the first using a ROI template and stringent quantitative perfusion criteria, the second exploring the whole affected vascular territory based on visual assessment; $: Data provided by the author following personal request; @: stroke onset-to-imaging time; &: stroke onset-to-inclusion time; #: stroke onset-to-door time; §: patients with parenchymal hematoma were excluded, and areas with HI-2 according to ECASS classification 45 were excluded from analysis. Δ: Exclusion of patients with parenchymal hematomas; ¥: Hemorrhagic areas not excluded in qualitative analysis of hypoperfusion and excluded in the quantitative analysis, but hypoperfusion was measured in peripheral hematoma area; ∞: Exclusion of “bleedings and hemorrhagic tissue transformation”; £: Among the 5 m/eTICI2c-3 patients with hypoperfusion, 4 (80%) had hemorrhagic transformation: 2 each with mTICI3 and mTICI2c recanalization; ¤: Incomplete microvascular reperfusion was not statistically associated with functional independence at 3 months after exclusion of patients with missing follow-up or strokes in multiple territories.
ASL: arterial spin labeling; CTP: computed tomography perfusion; ICA: internal carotid artery; MRI: magnetic resonance imaging; MT: mechanical thrombectomy; PWI: perfusion weighted imaging; TICI: thrombolysis in cerebral infarction (mTICI: modified TICI; eTICI: expanded TICI); CBF: cerebral blood flow; CBV: cerebral blood volume; DT: delay time.