Impact of prior intravenous thrombolysis on first-line thrombectomy strategy. A secondary analysis of the VECTOR trial

INTRODUCTION: 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. PATIENTS AND METHODS: 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. RESULTS: 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). DISCUSSION: 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. CONCLUSIONS: 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.