Early Response to Endovascular Thrombectomy after Stroke: Early, Late, and Very Late Time Windows

Abstract

<b><i>Background and Purpose:</i></b> Endovascular thrombectomy (EVT) has benefits in selected patients 6–24 h after stroke onset. However, the response to EVT >24 h after stroke onset is still unclear. We compared the early response to EVT in patients with different time windows. <b><i>Methods:</i></b> Patients who underwent EVT in an emergency setting were enrolled and categorized according to when EVT was performed: within 6 (early), 6–24 (late), and >24 h (very late) after stroke onset. Early neurological improvement (ENI) and deterioration (END) were defined as improvement and worsening, respectively, of National Institutes of Health Stroke Scale (NIHSS) score by ≥4 points after EVT. The three groups’ clinical characteristics and response to EVT were compared. We also investigated factors associated with ENI and END. <b><i>Results:</i></b> During study period, 274 patients underwent EVT (109 early, 104 late, and 61 very late). Patients who underwent EVT very late were younger (<i>p</i> = 0.007), had smaller ischemic cores, and had lower initial NIHSS scores (8 ± 5) than those who underwent EVT early (14 ± 6) and late (13 ± 7; <i>p</i> < 0.001). Stroke mechanisms also differed according to the time window (<i>p</i> < 0.001): cardioembolism was more common after early EVT, whereas large-artery atherosclerosis was more prevalent among patients who underwent EVT very late. ENI was significantly more common after early (60.6%) and late EVT (51.0%) than after very late EVT (29.5%; <i>p</i> = 0.001); however, rates of END did not differ (11.0%, 13.5%, and 4.9%, respectively). ENI was independently associated with male, higher NIHSS score, and early and late EVT. END was associated with failure of recanalization. <b><i>Conclusions:</i></b> ENI was more observed and associated with early and late EVT. Highly selected patients receiving very late EVT may not benefit from ENI but may still have a chance to prevent END. The occurrence of END was associated not with time window but with failure of recanalization.

Endovascular Therapy for Stroke Presenting Beyond 24 Hours

“…Of these 14 studies, 7 were excluded (eFigure 1 in Supplement 1). Thus, 7 studies [5][6][7][8][9][10][11] with a total of 569 patients were determined to satisfy our inclusion criteria with the appropriate report of outcomes of interest.…”

“…Sample sizes of the included studies ranged from 21 to 185 patients. Six studies 5,6,[8][9][10][11] were determined to have good quality and 1 study 7 was determined to have fair quality Of the 569 included patients, 312 (55.3% [95% CI, 50.9%-59.6%]) were men and 253 (44.7%) were women. A total of 35 patients received intravenous thrombolytics (4.9% [95% CI, 1.9%-12.2%]; eFigure 2 in Supplement 1).…”

“…Six studies 5,[7][8][9][10][11] involving 463 patients reported on 90-day functional independence (the primary outcome) using mRS scores of 0 to 2, with a frequency of 32.0% (95% CI, 24.7%-40.2%). However, there was significant heterogeneity among the pooled studies (I 2 = 66%, P = .01; Figure 1 and eFigure 4 in Supplement 1).…”

“…Seven studies [5][6][7][8][9][10][11] involving 553 patients reported TICI scores of 2b to 3 and 3, with a frequency of 81.9% (95% CI, 78.5%-84.9%). There was no heterogeneity among the pooled studies (I 2 = 0%, P = .60; Figure 2A and eFigure 5 in Supplement 1).…”

“…To our knowledge, no RCTs have been conducted in this patient population, although smaller studies have been published reporting outcomes following EVT in the very late window. [5][6][7][8][9][10][11] Therefore, we conducted a systematic review and meta-analysis of published studies evaluating outcome distributions of EVT performed more than 24 hours after last known well.…”