Study Synopsis

Protocol Title

Endovascular Acute Stroke Intervention – Tandem OCclusion trial (EASI-TOC): a trial of acute cervical internal carotid artery stenting during endovascular thrombectomy for anterior circulation stroke (NCT04261478)

Clinical Trial Phase

Phase III study

Planned Study Duration

6 years


Clinical Sites

12-14 high-volume comprehensive stroke centres in Canada  

Coordinating Site

Centre Hospitalier de l’Université de Montréal (CHUM)

Center for the Integration and Analysis of Medical Data (CITADEL

Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM)


The primary objective:

To determine if, in patients undergoing intracranial thrombectomy for anterior circulation stroke with concurrent ipsilateral symptomatic high-grade (>70%) atherosclerotic stenosis or occlusion of the cervical ICA (tandem lesion), acute cervical ICA stenting in addition to intracranial thrombectomy is superior to intracranial thrombectomy alone without acute cervical ICA stenting with regards to functional outcome at 90 days.


Experimental Design

A multi-centre, prospective, randomized, open-label, blinded endpoint (PROBE) controlled trial (1:1 allocation).


458 male and female adult (aged ≥ 18 years) patients.

Inclusion criteria:


Exclusion criteria:


Patients will be randomized (1:1) to undergo acute ICA stenting during the thrombectomy procedure (either before or after intracranial thrombectomy, at the discretion of the treating physician) or to intracranial thrombectomy alone without ICA stenting. Deferred ICA intervention is allowed, if indicated.

Duration of Treatment

Patients will be treated acutely and followed up to one year.

Evaluation Criteria

Primary outcome:

The proportion of patients achieving a favorable modified Rankin scale score (mRS 0-2) at 90 days (dichotomized)

 Secondary outcomes:


Safety outcomes:


Tertiary (descriptive) outcomes:


Sample Size

Our primary hypothesis assumes a greater proportion of patients with 90-day mRS 0-2 in the stenting group versus the no stenting group (55% versus 40%). In order to detect this 15% absolute risk difference in the primary outcome with power of 0.8, 173 patients per group will be required. A 15% minimal clinically important difference thus translates into an expected difference of 13.5 % (15%*0.9) with crossover. A sample of 217 patients per group (n total = 434) would detect the alternative hypothesis with 80% power at a 5% significance level. This includes adjustments for one interim analysis when 67% of the data has been collected, using the O’Brien-Fleming α-spending function stopping boundaries for efficacy.  Further adjusting for a loss to follow-up of 5%, the study would require a total sample size of 458 patients (n= 229 per group).  

Primary analysis will be by Intention-to-treat. Pre-specified per-protocol and sex-specific analyses will also be performed.


Randomization will be 1:1 to acute cervical ICA stenting or to no stenting. Randomization will be centralized and web-based. Stratification will be performed for use or not of IV alteplase.


Informed consent will be obtained from patients or their surrogate. Deferral of consent will be allowed if permitted by local ethics committees.