Intravenous tirofiban following successful reperfusion in intracranial large artery atherosclerotic stroke: A secondary analysis of a randomized clinical trial

Abstract Objective This study aimed to investigate whether treatment with adjunct intravenous tirofiban is associated with improved outcomes following successful reperfusion in patients with intracranial atherosclerotic stroke. Methods Patients with intracranial large artery atherosclerotic (LAA) stroke and an expanded Treatment in Cerebral Ischemia angiographic score of 2b50 to 3 from the Effect of Intravenous Tirofiban versus Placebo Before Endovascular Thrombectomy on Functional Outcomes in Large Vessel Occlusion Stroke (RESCUE BT) trial were included. The primary outcome was the difference in proportion of independent functional outcome (modified Rankin score of 0–2 at 90 days). Safety outcomes included the rates of symptomatic intracranial hemorrhage (sICH) and 90‐day mortality. Results Among the 382 patients with intracranial LAA stroke and successful reperfusion, 175 patients (45.8%) were treated with intravenous tirofiban and 207 (54.2%) with placebo. The proportion of patients with independent functional outcome at 90 days was 54.3% (95 out of 175) with tirofiban and 44.0% (91 out of 207) with placebo (adjusted odds ratio [aOR], 1.58; 95% CI, 1.02–2.44; p = 0.04). Intravenous tirofiban was not significantly associated with an increased risk of sICH (12/175 [6.9%] vs. 11/207 [5.3%]; aOR, 1.41; 95% CI, 0.59–3.34; p = 0.44) or 90‐day mortality (21/175 [12.0%] vs. 34/207 [16.4%]; aOR, 0.71; 95% CI, 0.38–1.31; p = 0.27). Interpretation Among patients with acute intracranial LAA stroke and successful reperfusion following endovascular thrombectomy, adjunct intravenous tirofiban was associated with a higher rate of independent functional outcome, without higher rates of sICH or mortality. Confirmatory randomized trials in these patients are desirable.


Introduction
Endovascular thrombectomy (EVT) is the standard treatment to improve functional outcomes in acute ischemic stroke patients with large vessel occlusion. 1,2However, despite advances in thrombectomy devices and optimization of treatment workflow processes, outcomes remain suboptimal.Notably, even when EVT yields successful reperfusion (expanded Thrombolysis In Cerebral Infarction [eTICI] scale 2b50-3) acutely, only one half of patients achieve functional independence at 90 days. 3,4art of this incomplete recovery reflects infarction that ª 2023 The Authors.Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
accrued prior to intervention.But another important mechanism may be post-procedure infarct progression in regions with insufficient macrocirculatory and microcirculatory reperfusion despite successful recanalization of the target large vessel occlusions at the end of procedure. 5 recent randomized trial showed that adjunct intraarterial alteplase infused after achievement of successful reperfusion with EVT improved neurological outcomes at 90 days in patients with acute ischemic stroke, suggesting that functional outcome can be improved by facilitating macrocirculatory and microcirculatory reperfusion. 6mong patients with successful reperfusion with EVT, residual blood flow impairment is of two types: macrocirculatory-angiographically visible occlusions in more distal arteries; and microcirculatory-no reflow at the arteriolar-capillary level despite absence of any angiographically visible occlusion.For example, in patients with eTICI 3 outcome, no visible occlusions are present but hypoperfusion throughout the field may occur due to microcirculatory obstructions.
Intracranial large artery atherosclerotic (LAA) stroke is one of the most common etiologies of large artery occlusion, especially in Asian patients. 7,8Compared to cardiac embolism, LAA predicts a lower chance of successful reperfusion and worse functional outcomes after EVT. 9 Recently, the Endovascular Treatment With versus Without Tirofiban for Stroke Patients with Large Vessel Occlusion (RESCUE BT) trial showed that administer intravenous tirofiban before EVT does not improve functional outcomes in patients with acute large vessel occlusion stroke. 10However, there was a hint of benefit with tirofiban in patients with LAA stroke, although there were no significant interactions among various subgroups.In the post hoc study, we evaluate trial findings regarding the association of adjunct intravenous tirofiban with functional outcome specifically in intracranial LAA patients in whom EVT yielded successful reperfusion.

Study participants
The RESCUE BT trial was a multicenter, randomized, double blinded clinical trial conducted at 55 hospitals in China from October 2018 to October 2021.Details of trial design and topline results have been described previously. 10,11Briefly, patients with acute ischemic stroke attributed to large vessel occlusion within 24 h of time last known well were enrolled.Inclusion criteria were: (1) age ≥18 years old; (2) National Institutes of Health Stroke Scale (NIHSS) score ≤30; (3) Alberta Stroke Program Early CT Score (ASPECTS) score ≥6； (4) occlusion of the intracranial internal carotid artery, the first or second segment of the middle cerebral artery confirmed by computed tomography angiography, magnetic resonance angiography, or digital subtraction angiography; (5) without intravenous thrombolysis due to contraindication or no consent for thrombolysis given.The study protocol was approved by the ethics committees of the Xinqiao Hospital, Army medical university and all participating centers.Written informed consent was obtained from all the patients or their legally authorized representatives.
For the current post hoc study, additional inclusion criteria were, (6) diagnosis of intracranial large artery atherosclerosis as the mechanism of the index ischemic stroke, and (7) achievement of successful reperfusion at the end of the mechanical thrombectomy procedure.Successful reperfusion was defined as an eTICI grade of 2b50-3, including 2b50 (substantial reperfusion, 50-89%), 2c (excellent reperfusion, 90-99%), and 3 (completely reperfusion, 100%). 12In the RESCUE BT trial, stroke mechanism was defined based on the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification. 13Intracranial LAA-related stroke was considered present when there was obvious (50-99%) residual focal stenosis at the occlusion site after mechanical thrombectomy, accompanied by 1 or more high risk factors for atherosclerosis, such as advanced age, history of smoking, diabetes, hypertension, hyperlipidemia, etc.Some of the information on risk factors may not be available at the time of the procedure, therefore, the physician can apply the clinical and imaging findings when first assessing the patient and then consider the results of other diagnostic tests later.

Study treatments and interventions
The study drug was administered intravenously within 5 min after randomization.Eligible participants in the tirofiban group received intravenous bolus followed by continuous infusion of tirofiban (10 lg/kg bolus and then 0.15 lg/kg/min maintenance for up to 24 h), participants in the placebo group received saline.A rapid EVT was initiated.It was permitted to use rescue drug when reocclusion of the target artery after EVT was observed in the angiographic suite.The rescue drug was saline placebo in the tirofiban group and tirofiban in the placebo group.Patients who achieved successful reperfusion after use of rescue drug were included in this analysis in addition to those not requiring rescue drug.

Outcomes measures
This analysis used the same primary and all applicable secondary efficacy analyses used for the parent trial.The primary efficacy outcome measure was the proportion of patients functionally independent (modified Rankin Scale [mRS] score of 0 to 2) at 90 days.The mRS score is an ordered scale ranging from 0 (no symptoms) to 6 (death).
Secondary efficacy outcomes included a shift analysis of the mRS score at 90 days; the proportion of patients disability-free (mRS score 0 to 1); the change of the NIHSS score from baseline to 24 h and 5-7 days (or at discharge if earlier); the score of the European Quality of Life 5-Dimension 5-level scale (EQ-5D-5L; a higher score indicates a better quality of life) at 90 days.Safety outcomes included incidence of symptomatic intracerebral hemorrhage (sICH) according to Heidelberg Bleeding Classification, 14 mortality within 90 days, and serious adverse events.

Statistical analysis
Continuous variables were reported as medians (interquartile ranges) and categorical variables as numbers (percentages).Baseline characteristics between patients with and without intravenous tirofiban were compared by using the Wilcoxon rank sum test or chi-squared test as appropriate.The main efficacy outcome was estimated using a multivariable logistic regression model adjusted for age, baseline NIHSS score, baseline ASPECTS, occlusion site, time from last known well to randomization.In a sensitivity analysis, the estimated odds ratio of effect of intravenous tirofiban on independent functional outcome was performed between the tirofiban group and the placebo group only among patients who did not receive rescue drug.
Among secondary clinical outcomes, the improvement in mRS score at 90 days was estimated by ordinal logistic regression model adjusted for the same variables above.The odds ratios for early neurological changes (the change of the NIHSS score from baseline to 24 h and 5-7 days) and quality of life at 90 days were analyzed using multivariable linear regression model.The risk ratio for safety outcomes was estimated by Poisson regression model.The unadjusted and adjusted value were presented with 95% confidence intervals to indicate statistical precision.
Subgroup analyses were performed evaluating potential heterogeneity for efficacy effect among patients with substantial reperfusion (eTICI 2b50), excellent reperfusion (eTICI 2c), and complete reperfusion (eTICI 3), using forest plot analysis.Day 90 functional outcomes analyzed included the primary outcome (mRS 0-2), the prespecified secondary mRS outcomes (mRS 0-1).Heterogeneity was assessed by interaction p value and I 2 , which describes the percentage of variability in the estimates that is due to heterogeneity rather than chance.We considered evidence of heterogeneity to be present if the I 2 statistic was greater than 50%.
Additional subgroup analyses were performed for the primary mRS 0-2 outcome stratified by the same variables as in the overall trial analysis: age, sex, baseline NIHSS score, baseline ASPECTS, occlusion site, time from last known well to randomization.All analyses were performed using SPSS version 23 (IBM Corp.) and Review Manager 5.3.For main effect analyses, p ≤ 0.05 (two-sided) was considered statistically significant.For subgroup analyses, p ≤ 0.10 (two-sided) was considered statistically significant. 15

Primary efficacy outcome
Treatment with intravenous tirofiban was associated with independent functional outcome (mRS 0 to 2) at 90 days in 54.3% (95 out of 175) patients in the tirofiban group and 44.0%(91 out of 207) patients (44.0%) in the placebo group (adjusted odds ratio [aOR], 1.58; 95% CI, 1.02-2.44;p = 0.04) (Table 2 and Fig. 2).Similarly, the sensitivity analysis, confined to patients with successful reperfusion without use of rescue therapy, showed that the proportion of patients achieving functional independence in the tirofiban group was significantly higher than that of the placebo group (95 out of 175 [54.3%] vs. 67 out of 156 [42.9%]; aOR, 1.60; 95% CI, 1.02-2.52;p = 0.04) (data not shown).The proportion of independent functional outcome showed no significant difference between the treatment groups in patients with unsuccessful reperfusion.

Subgroup analyses
The effects of tirofiban stratified by reperfusion grade on the primary outcome, the secondary efficacy outcomes, and primary safety outcomes were shown in Figure 3.For the primary functional independence (mRS 0-2) outcome, in unadjusted analysis there was evidence of heterogeneity of treatment effect with different reperfusion levels, I 2 = 63%, P (interaction) = 0.07.Among patients with eTICI 2b50, the proportion achieving independent functional outcome (mRS of 0 to 2) was increased with tirofiban (45% vs. 20%; OR 3.27; 95% CI, 1.29-8.31).There was no significant heterogeneity of effect of the functional outcome across the subgroup: age, sex, baseline ASPECTS, occlusion site, time from last known well to randomization (Fig. 4).A trend was noted to magnified benefit in patients with higher NIHSS scores.

Discussion
This study focused on the population of patients with acute ischemic stroke due to intracranial large artery atherosclerotic disease, which is a main cause of stroke in Asian patients and a determinant of poor outcome.Randomized studies evaluating the outcome of EVT in patients with intracranial LAA were sparse.Among intracranial LAA patients with successful reperfusion (eTICI 2b50-3), periprocedural intravenous tirofiban treatment was associated with improved functional outcome at 90 days, and rates of death and sICH were comparable between the two groups.The magnitude of treatment effect was sizable, with the number needed to treat for one more functional independent outcome at 90 days of 9.7.Due to the post hoc secondary analysis design and limited size of successful population, all of the results were exploratory.
In the overall RESCUE BT trial, mechanisms of qualifying ischemic stroke were LAA in 45.9%, cardioembolic in 42.8%, other in 2.3%, and unknown in 8.1% and tirofiban

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was associated with improved outcomes only in the LAA patients. 10This finding accords with the pharmacophysiological effects of tirofiban.Tirofiban, a glycoprotein IIb/IIIa receptor inhibitor, exerts a powerful antiplatelet effect by antagonizing the final common step in the aggregation of activated platelets. 16Atherosclerotic lesions with their irregular surfaces and disruption of laminar flow streams are particularly likely to activate platelets.This inherent tendency is likely further magnified by mild endothelial injury and plaque disruption caused by EVT device passes during the procedure.Our results are consistent with a beneficial effect of tirofiban in blocking activated platelets, inhibiting acute thrombosis formation, reducing reocclusion at the treatment site, reducing potential artery to artery from the treatment site, and enhancing the dissolution of thrombi distal to the treatment site.In patients with non-LAA stroke, it seemed that tirofiban could not improve the clinical outcomes.On the contrary, higher proportion of sICH and mortality at 90 days were observed in these patients treated with intravenous tirofiban.Previous study illustrated that low-dose tirofiban was not associated with sICH in cardioembolic stroke patients treated with EVT. 17 A subgroup analysis of the RESCUE BT found that tirofiban increased the risk of sICH after EVT in cardioembolized stroke patients. 18Therefore, it is still unclear whether intravenous tirofiban is safe or not in patients with non-LAA stroke, future trials are needed.Intriguingly, among LAA patients there was evidence of heterogeneity of treatment effect across different eTICI reperfusion levels.Tirofiban was associated with improved outcomes among patients with substantial reperfusion (eTICI 2b50), but no statistically significant effect was seen for patients with excellent (eTICI 2c) or complete (eTICI 3) reperfusion.This observation supports a role for tirofiban in resolving or stabilizing residual microcirculatory obstructions angiographically visible in distal fields at the end of the thrombectomy procedure.Conversely, this finding suggests that an effect of tirofiban upon microcirculatory reperfusion is less marked or absent.
Among LAA patients with successful reperfusion, intravenous tirofiban was associated with an increased rate of any radiologic intracranial hemorrhage but not symptomatic intracranial hemorrhage or mortality.This finding suggests that the antiplatelet effect of intravenous tirofiban may increase rates of any hemorrhagic transformation of bland infarcts but may not predispose to major hemorrhage to the same degree.In addition, the extended EVT treatment time window may have contributed to increased rates of intracranial hemorrhage in both treatment groups in the current study.
The strengths of our study included the large-scale, double-blind, and placebo-controlled design.This study also has several limitations.First, it was a post hoc analysis, multiple testing may increase the risk of Type I errors.All the results should be interpreted with caution.Second, only Chinese patients with LAA stroke were enrolled in the trial, which may reduce the generalizability of study findings.Third, the selection for patients in the extended therapeutic window was based on ASPECTS score according to non-contrast CT scan rather than CT perfusion assessment, as automated CT perfusion analysis software was not available in many of participating hospitals due to high cost.Fourth, end-of-procedure reperfusion grade is an early post-randomizing rather than baseline patient characteristics, necessitating caution regarding subgroup findings.However, study treatment on average was started coincident with, not before, arterial puncture and only a

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small fraction of treatment agent was administered before reperfusion grade was assessed.Fifth, analyses are generally more statistically powerful when continuous measures are used rather than dichotomies in the subgroup analysis.Interpretation of the results should be more cautious.

Conclusions
Among patients with large vessel occlusion due to large artery atherosclerotic stroke and successful reperfusion after endovascular thrombectomy, adjunct intravenous tirofiban was associated with a higher rate or independent functional outcome, without higher rates of symptomatic intracranial hemorrhage or mortality.Confirmatory randomized trials in these patient populations are desirable.

Patient Consent for Publication
Not applicable.

2044 ª 2023
The Authors.Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.

ª
2023 The Authors.Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.

Figure 2 .
Figure 2. Distribution of the Modified Rankin Scale score at 90 days.

Figure 3 .
Figure 3. Heterogeneity analysis for intravenous tirofiban effect on outcomes with stratified reperfusion grades.

Table 1 .
Baseline characteristics and workflow measures.
*p values were calculated using Fisher exact tests.ª 2023 The Authors.Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.

Table 2 .
Efficacy and safety outcomes.Values were adjusted for age, baseline NIHSS score, baseline ASPECTS, occlusion site, and time from last known well to randomization.
1 2 Values were calculated using ordinal logistic model.*Values were calculated using linear regression model.2048 ª 2023 The Authors.Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.

Table 3 .
Safety outcomes of the cohort.