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Abstract 073: Thrombectomy Alone Versus Bridging Intravenous Alteplase in A US Population: Regression Discontinuity Analysis
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Abstract 073: Thrombectomy Alone Versus Bridging Intravenous Alteplase in A US Population: Regression Discontinuity Analysis

Ngoc Mai Le, Youngran Kim, Sergio Salazar-Marioni, Arash Niktabe, Anjan Ballekere, Rania Abdelkhaleq, Ananya Iyyangar, Hussain Azeem, Diogo Haussen, Jonathan Grossberg, …
Stroke: vascular and interventional neurology, Vol.3(S2), e12823_073
11/01/2023
DOI: 10.1161/SVIN.03.suppl_2.073
url
https://www.ahajournals.org/doi/10.1161/SVIN.03.suppl_2.073View
Published (Version of record) Open Access

Abstract

Introduction Recent randomized controlled trials (RCT) failed to demonstrate the non‐inferiority of skipping IV tPA in patients with planned endovascular therapy (EVT). None of these studies included patients from the US due to regulatory challenges. Given that practice patterns vary relative to Asia, Australia, and Europe, we sought to address this topic using a validated alternative to RCTs, regression discontinuity (RD). Methods From the prospectively collected SVIN Registry encompassing all consecutive patients treated with EVT from 12 centers across the US, we identified patients from 12/2010 – 12/2021. RD design achieves quasi‐randomization and can determine causal effects by analyzing subjects on immediately adjacent sides of a cutoff. Here, we take advantage of the sharp drop in the likelihood of IV tPA treatment at the 4.5‐hour mark from the patients’ last known well time. Subjects immediately on either side of the cutoff have markedly different probabilities of receiving the treatment while sharing similar characteristics in other relevant aspects. Patients were excluded if they underwent EVT after inter‐hospital transfer, were inpatient at the time of acute ischemic stroke (AIS), received IV tPA outside the 4.5‐hour window, or were treated with EVT after the 10‐hour window, as these patients would not contribute to the RD analysis. The primary outcome was a good functional outcome defined as 90‐day mRS 0‐2 and was analyzed using validated RD analysis methods with local linear regressions and triangular kernel weights. Secondary endpoints included rates of symptomatic intracranial hemorrhage and substantial reperfusion. Results Among 961 patients who met inclusion criteria, all 12 EVT centers within the SVIN Registry were represented. The median age was 70 [IQR 58‐79], 48% were female, NIHSS was 17, and the most common occlusion location was M1 MCA (45%). There were no substantial differences in presentation characteristics between patients treated with IV tPA and without. We observed a significant fall (30%) in the probability of tPA around the cutoff time of 235 minutes from the last known well to hospital arrival (allowing 35 minutes for in‐hospital evaluation from the 4.5‐hour cutoff), while there were no significant differences in other relevant features including age, NIHSS, ASPECTS, and final reperfusion grade at the cutoff, validating the underlying RD assumptions (Figure A). In RD analysis, we observed no association between IV tPA treatment and functional independence at 90‐days in patients undergoing EVT (risk difference ‐0.29 (95% CI [‐2.75 to 2.15]) (Figure B), nor in the secondary outcomes of excellent outcomes (mRS 0‐1) at 90 days, mortality, symptomatic ICH or first pass reperfusion. Conclusion Here, we perform what we believe to be the strongest study to date examining the benefit of IV tPA in patients undergoing EVT for LVO AIS in a US‐based cohort, and we find no evidence of association with 90‐day functional independence, consistent with findings of RCTs performed outside the US.

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