Neurology · Medical Literature
Impact of prior intravenous thrombolysis on first-line thrombectomy strategy. A secondary analysis of the VECTOR trial.
Abstract
Whether prior intravenous thrombolysis (IVT) modifies the relative efficacy of first-line thrombectomy strategies remains uncertain, and no randomised trial has specifically addressed this question. Leveraging the randomised design of the VECTOR trial, a multicentre trial comparing first-line contact aspiration (CA) vs CA plus stent retriever (SR + CA) in patients with anterior LVOs and a positive susceptibility vessel sign, we assessed whether IVT status modified the association between thrombectomy strategy and reperfusion outcomes. We performed a secondary analysis of the VECTOR trial, in which patients were stratified according to prior IVT use. The primary outcome was near-complete or complete reperfusion (expanded thrombolysis in cerebral infarction [eTICI] 2c-3) after ≤ 3 passes with the assigned first-line technique and before rescue therapy. Secondary outcomes included first-pass reperfusion, complete reperfusion after ≤ 3 passes, final reperfusion at the end of the procedure and functional outcomes at 90 days. Between 26 November 2019 and 14 February 2022, 521 patients were included in VECTOR. Of these, 288 (55%) received IVT before thrombectomy. The effect of first-line strategy on the primary outcome did not differ according to IVT status (P for heterogeneity = .28). Among IVT-treated patients, eTICI 2c-3 after ≤ 3 passes occurred in 88/144 patients (61.1%) assigned to SR + CA vs 74/144 (51.3%) assigned to CA (aOR, 1.50 [95% CI, 0.91-2.45]). Among patients without IVT, corresponding rates were 64/119 (53.9%) vs 61/114 (53.6%) (aOR, 1.00 [95% CI, 0.58-1.72]). Interaction tests were non-significant for all other angiographic, clinical and safety outcomes except final complete reperfusion, which favoured CA in patients without IVT (P for heterogeneity = .019). Prior IVT did not significantly modify the effect of first-line strategy on early reperfusion, and both CA and SR + CA remained valid approaches irrespective of IVT status. The isolated interaction for final complete reperfusion, favouring CA in patients without IVT, was exploratory and may reflect chance. A hypothesis-generating mechanism is plausible in this SVS-positive, red blood cell-rich phenotype: CA applied to an intact clot may favour en-bloc retrieval, an advantage attenuated once alteplase softens the thrombus. These results, obtained almost exclusively under alteplase and in an MRI-selected population with mandatory balloon guide catheter use, may not extend to tenecteplase or CT-selected patients. In this secondary analysis of the VECTOR trial, prior IVT did not significantly modify the association between first-line thrombectomy strategy and successful reperfusion. The observed angiographic differences remain exploratory and warrant further investigation.
Clinical relevance
The optimal first-line mechanical thrombectomy strategy for anterior large vessel occlusion (LVO) may theoretically differ based on whether bridging intravenous thrombolysis (IVT) was administered prior to the procedure, given that alteplase-mediated thrombus softening could alter clot-device interaction mechanics. This secondary analysis of the VECTOR trial addresses a clinically important and previously unanswered question in a population enriched for red blood cell-rich thrombi (susceptibility vessel sign-positive), which represents a common and pharmacologically relevant subset of LVO stroke patients. As direct-to-thrombectomy paradigms and tenecteplase adoption continue to evolve, understanding whether IVT status should guide device selection at the start of thrombectomy is of immediate practical relevance to interventional neurologists.
Key findings
1. Prior IVT status did not significantly modify the effect of first-line thrombectomy strategy on the primary outcome of near-complete or complete reperfusion (eTICI 2c-3) after ≤3 passes (P for heterogeneity = .28). 2. Among IVT-treated patients (n=288, 55% of cohort), eTICI 2c-3 after ≤3 passes was achieved in 61.1% (88/144) with SR+CA vs. 51.3% (74/144) with CA alone (aOR 1.50, 95% CI 0.91–2.45), a numerically favorable but non-significant difference. 3. Among patients without prior IVT (n=233), eTICI 2c-3 after ≤3 passes rates were nearly identical: 53.9% (64/119) with SR+CA vs. 53.6% (61/114) with CA alone (aOR 1.00, 95% CI 0.58–1.72). 4. Interaction tests for all other angiographic, clinical, and safety outcomes were non-significant, with the sole exception of final complete reperfusion, which favored CA over SR+CA exclusively in patients without prior IVT (P for heterogeneity = .019). 5. The trial enrolled 521 patients across a multicenter randomized design between November 2019 and February 2022, with mandatory balloon guide catheter use and an MRI-selected (SVS-positive) population, limiting generalizability. 6. No significant interaction was detected for functional outcomes at 90 days according to IVT status, reinforcing that neither strategy demonstrated superiority based on thrombolysis pre-treatment in this cohort.
Practice implications
Based on this analysis, interventional neurologists should not routinely alter their first-line thrombectomy device selection — between contact aspiration alone or combined SR+CA — solely on the basis of whether bridging IVT was administered, as neither strategy demonstrated a statistically significant benefit conditioned on IVT status. The exploratory finding favoring CA monotherapy for final complete reperfusion in IVT-naïve, SVS-positive patients is hypothesis-generating and could reflect en-bloc clot retrieval advantage when the thrombus remains structurally intact, but it should not yet change practice without confirmatory prospective data. These results apply specifically to alteplase-bridged or direct-thrombectomy patients with anterior LVO and a positive SVS on MRI using balloon guide catheters, and should not be extrapolated to tenecteplase-treated or CT-selected patient populations without further study.