Noncontrast Computed Tomography vs Computed Tomography Perfusion or Magnetic Resonance Imaging Selection in Late Presentation of Stroke With Large-Vessel Occlusion

Abstract

OBJECTIVETo compare the clinical outcomes of patients selected for mechanical thrombectomy by noncontrast computed tomography (CT) vs those selected by computed tomography perfusion (CTP) or magnetic resonance imaging (MRI) in the extended time window. DESIGN, SETTING, AND PARTICIPANTSThis multinational cohort study included consecutive patients with proximal anterior circulation occlusion stroke presenting within 6 to 24 hours of time last seen well from January 2014 to December 2020. This study was conducted at 15 sites across 5 countries in Europe and North America. The duration of follow-up was 90 days from stroke onset.EXPOSURES Computed tomography with Alberta Stroke Program Early CT Score, CTP, or MRI. MAIN OUTCOMES AND MEASURESThe primary end point was the distribution of modified Rankin Scale (mRS) scores at 90 days (ordinal shift). Secondary outcomes included the rates of 90-day functional independence (mRS scores of 0-2), symptomatic intracranial hemorrhage, and 90-day mortality. RESULTSOf 2304 patients screened for eligibility, 1604 patients were included, with a median (IQR) age of 70 (59-80) years; 848 (52.9%) were women. A total of 534 patients were selected to undergo mechanical thrombectomy by CT, 752 by CTP, and 318 by MRI. After adjustment of confounders, there was no difference in 90-day ordinal mRS shift between patients selected by CT vs CTP (adjusted odds ratio [aOR], 0.95 [95% CI, 0.77-1.17]; P = .64) or CT vs MRI (aOR, 0.95 [95% CI, 0.8-1.13]; P = .55). The rates of 90-day functional independence (mRS scores 0-2 vs 3-6) were similar between patients selected by CT vs CTP (aOR, 0.90 [95% CI, 0.7-1.16]; P = .42) but lower in patients selected by MRI than CT (aOR, 0.79 [95% CI, 0.64-0.98]; P = .03). Successful reperfusion was more common in the CT and CTP groups compared with the MRI group (474 [88.9%] and 670 [89.5%] vs 250 [78.9%]; P < .001). No significant differences in symptomatic intracranial hemorrhage (CT, 42 [8.1%]; CTP, 43 [5.8%]; MRI, 15 [4.7%]; P = .11) or 90-day mortality (CT, 125 [23.4%]; CTP, 159 [21.1%]; MRI, 62 [19.5%]; P = .38) were observed. CONCLUSIONS AND RELEVANCEIn patients undergoing proximal anterior circulation mechanical thrombectomy in the extended time window, there were no significant differences in the clinical outcomes of patients selected with noncontrast CT compared with those selected with CTP or MRI. These findings have the potential to widen the indication for treating patients in the extended window using a simpler and more widespread noncontrast CT-only paradigm.

Association between time to treatment and clinical outcomes in endovascular thrombectomy beyond 6 hours without advanced imaging selection

“…We included 3278 patients: 2610 (79.6%) treated within 6 hours (early window), and 668 (20.4%) treated between 6 to 24 hours (late window); 141 patients had significant pre-stroke disability (mRS 3–5) and 179 patients had an NIHSS score <6 on admission; 2196 patients (67.0%) had a documented precise time of stroke onset, while the remainder were documented as last known well. Compared with the early window, patients treated in the late window were younger, had a lower baseline stroke severity (NIHSS) (median 169–20 vs 1813–22), had lower rates of IV-tPA use (33.8% vs 62.9%), were more likely to undergo general anesthesia (61.5% vs 51.5%), and were more likely to be treated using a stent retriever or a combined technique of stent retriever and thromboaspiration (table 1 and online supplemental table 1). No significant differences were observed in the remaining baseline characteristics between the two time windows.…”

“…Previous observational studies assessing overall rates of functional independence (mRS ≤2) in the late EVT window have reported different results at 90-day follow-up, ranging from 20% to 64% using various pre-specified clinical and imaging patient selection criteria 8–11 18 20–23. Some of these investigations incorporated perfusion-based imaging with varying adherence to the DAWN and DEFUSE-3 eligibility criteria,18 20–23 while others used solely NCCT and CTA, but also varied in their selection criteria 8–11.…”

“…Ongoing RCTs are assessing whether treatment benefit with EVT is maintained in patients presenting beyond 6 hours of stroke onset when less restrictive clinical and imaging selection criteria are used 6 7. In the interim, functional and safety outcome data following EVT in the absence of CT perfusion or MR imaging in the late window is limited 8–11. Furthermore, while functional outcomes are highly time sensitive to EVT in the early (<6 hours) window, studies have reported a transition to a slower loss of effectiveness from EVT in the late window 12 13.…”

Evolution of Hypodensity on Non-Contrast CT in Correlation with Collaterals in Anterior Circulation Stroke with Successful Endovascular Reperfusion

“…This issue has been addressed in two recent studies by Hendrix et al [10] and Nguyen et al [11] which showed that there were no significant differences in clinical outcomes in proximal anterior stroke treated with MT in the late time window between patients selected solely with simple NCCT and those selected with advanced imaging. The authors concluded that their findings have the potential to widen the indication for treating patients in the extended window using simpler, less costly, and easier to implement NCCT imaging.…”

“…However, a recent study by Hendrix et al [10] as well as the multicentre international CLEAR trial (published by Nguyen et al in JAMA Neurology) [11] have shown that simple non-contrast CT (NCCT) alone may be just as useful as advanced imaging in selecting stroke patients with late-presenting LVO for MT, which could allow for a more pragmatic selection of patients in the extended window.…”