Middle Cerebral Artery AneurysmMCAATNCT05161377
Middle Cerebral Artery Aneurysm Trial
A study testing Surgical management and Endovascular management in people with Middle Cerebral Artery Aneurysm, run by University of Alberta at 1 site in Canada.
Trial summary
Intracranial aneurysms located on the middle cerebral artery (MCA) are considered by many surgeons to represent a distinct subgroup of aneurysms for which clipping may still be the best management option. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Middle Cerebral Artery Aneurysm
- What is being tested?
- Surgical management and Endovascular management
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 400 participants
- Where
- 1 siteCanada
- Study dates
- 15 May 2022to 1 Jan 2038
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients at least 18 years of age
- At least one documented, intradural, intracranial aneurysm anywhere on the course of the MCA vessel, ruptured or unruptured. An untreated ruptured aneurysm (with delay in diagnosis) which is suspected to have occurred more than 30 days prior to study inclusion will be considered an unruptured aneurysm
- In the case of SAH, WFNS grade 4 or less
- The patient and aneurysm are considered appropriate for either surgical or endovascular treatment by the treating team
Who cannot join
- Patients with absolute contraindications administration of contrast material (any type)
- Patients with AVM-associated aneurysms
- Patients or caregivers unable to provide consent
- Poor grade (WFNS 5) ruptured aneurysms
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
University of Alberta
Edmonton
Tim Darsaut, MD
tim.darsaut@ualberta.ca
About this study
Official title: Middle Cerebral Artery Aneurysm Trial: A Randomized Care Trial Comparing Surgical and Endovascular Management of MCA Aneurysm Patients
Intracranial aneurysms located on the middle cerebral artery (MCA) are considered by many surgeons to represent a distinct subgroup of aneurysms for which clipping may still be the best management option. Most MCA aneurysms are accessible, proximal control can readily be secured in case of rupture, and clip application can typically proceed without requiring the dissection of perforating arteries. In comparison, certain anatomic features of MCA aneurysms such as a wide neck, often including a branch artery origin, frequently render endovascular management more difficult. New endovascular devices were and continue to be introduced to address these anatomic difficulties, including stents, flow diverters, and intra-saccular flow disruptors (ISFDs) such as the WEB. Thus, while most aneurysms are increasingly treated with endovascular methods, many MCA aneurysm patients are still managed surgically, but convincing evidence of which management paradigm is best is lacking.
Read the detailed description
The subgroup results of ruptured MCA aneurysms taken from ISAT-2 has recently been published. This also suggested that better efficacy could be obtained with surgical management of ruptured MCA aneurysms, with a similar number of residual aneurysms at 1 year in each group (4 surgery, 5 endovascular), but 2 rebleedings from coiled aneurysms (one fatal) and 4 other aneurysms retreated due to growing recurrences discovered on short-term follow-up. Although the ISAT has shown that good-grade, small, anterior circulation aneurysms patients have better 1 year clinical outcomes after being coiled, which was further supported by the Barrow Ruptured Aneurysm Trial (BRAT) study, there are several reasons to suspect that those results do not apply to aneurysms located at the MCA bifurcation. Only 14% of aneurysms in ISAT were on the MCA, likely because lesions in this location were preferentially treated with surgery. Even after selection, the MCA subgroup results were similar for coiling and clipping (RR: 1.01 (0.71-1.45)).
First, the number of selected MCA aneurysm patients included in ISAT was disproportionately small (301/2143 or 14%, as compared to 38% in ISAT-2) and they were recruited between 1994 and 2004, a time when only simple coiling was available. The overall trial result of superior clinical outcomes at 1 year was not confirmed for MCA aneurysms. The clinical primary endpoint of mRS >2 was reached in 39/139 clipped (28.1%, 95% CI:0.21-0.36), and 46/162 coiled patients (28.4%, 95% CI:0.22-0.36).
The suspicion that only selected MCA aneurysm patients were judged eligible for endovascular treatment at the time of ISAT is supported by the pre-randomized BRAT study: Of 61 patients with ruptured MCA aneurysms included between 2003 and 2007, 30 were assigned clipping and 31 coiling. Twenty-one of the 31 (68%) endovascular patients were crossed-over to the surgical arm.15 The Finnish RCT on clipping versus coiling reported only 19 ruptured MCA aneurysms because 59 MCA aneurysm patients were excluded.
If most MCA aneurysms can now be treated endovascularly, clinical results of contemporary technical achievements remain to be properly compared to surgical clipping. In particular, although overall clinical results were similar at one year in ISAT-2, rebleedings and retreatments after endovascular treatment remain worrisome.
The final argument for a new trial dedicated to MCA aneurysms has to do with the eventual interpretation of trial results. ISAT-2 was designed to be, and can still be considered a continuation of the original ISAT trial, with a superiority hypothesis in favor of endovascular treatment. The results presented here suggest that this hypothesis may not be appropriate for ruptured MCA aneurysms. Showing a result for a MCA subgroup that differs from the overall results at the end of ISAT-2 risks being scientifically problematic just as in the original ISAT.
Taken together, the available data and foregoing rationale are sufficient to warrant the conduct of a separate trial of surgical clipping versus endovascular treatment for MCA aneurysms, both ruptured and unruptured. MCAAT will provide a transparent care trial context for clinicians to manage patients with MCA aneurysms.
- Conditions
- Middle Cerebral Artery Aneurysm
- Being tested
- Surgical management, Endovascular management
- Keywords
- Intracranial aneurysms
- Medical subject headings
- Intracranial Aneurysm
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Surgical managementProcedure or surgery
Surgical clipping will be performed following randomization according to standards of practice, and under general anesthesia. Aneurysms thought by the treating physicians to require deliberate permanent proximal vessel occlusion, construction of a surgical bypass, or other flow-redirecting treatments that do not directly clip the aneurysm will not be excluded; these aneurysms are expected to be more difficult lesions to manage surgically as well as endovascularly.
Endovascular managementProcedure or surgery
Endovascular treatment will also be performed following randomization, according to standards of practice, and under general anesthesia. Details regarding type of coils, use of adjunctive techniques such as balloon-remodeling, stents, flow-diverters, ISFD/WEBs or other innovative devices, as well as post- treatment medical management issues, will be left up to the physician performing the endovascular treatment and initial strategies determined prior to randomization.
| Study group | Role | What they receive |
|---|---|---|
| Surgical management | Active comparator | Not described Receives: Procedure: Surgical management |
| Endovascular management | Active comparator | Not described Receives: Procedure: Endovascular management |
What is being measured
The primary outcome is the main question the study is designed to answer.
Treatment Success
The primary composite outcome measure is Treatment Success, a 5-part composite comprising: 1) occlusion or exclusion of the aneurysm using the allocated treatment modality; 2) no intracranial hemorrhage during follow-up; 3) no re-treatment of the target aneurysm during follow-up, 4) no residual aneurysm at 1 year; 5) independence (mRS <3) at 1 year.
Measured: up to 5 Years or until death, whichever came first
Secondary outcomes (2)
The occurrence of an intracranial hemorrhage following treatment
An intracranial hemorrhage or re-bleed will be judged from cross-sectional imaging (CT or MRI), from a positive lumbar puncture in the setting of an acute headache, or following sudden death preceded by an acute headache.
Measured: Follow-up for 5 Years or until death, whichever came first
Failure of aneurysm occlusion using the intended treatment modality
This will be judged by the treating physician immediately following the attempted treatment.
Measured: Follow-up for 5 Years or until death, whichever came first
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Dec 2021
- Study start15 May 2022
- Primary completion1 Jan 2036 (estimated)
- Study completion1 Jan 2038 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Middle Cerebral Artery AneurysmStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 400 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Alberta
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Tim Darsaut, Principal investigator, University of Alberta Faculty of Medicine and Dentistry
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05161377
- Sponsor's protocol ID
- PRO-00116285
- Acronym
- MCAAT
- Status last verified
- Mar 2026
- First submitted
- 6 Dec 2021
- Last updated
- 13 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Data will be made available upon reasonable request.
Publications
Darsaut TE, Keough MB, Boisseau W, Findlay JM, Bojanowski MW, Chaalala C, Iancu D, Weill A, Roy D, Estrade L, Lejeune JP, Januel AC, Carlson AP, Sauvageau E, Al-Jehani H, Orlov K, Aldea S, Piotin M, Gaberel T, Gevry G, Raymond J. Middle Cerebral Artery Aneurysm Trial (MCAAT): A Randomized Care Trial Comparing Surgical and Endovascular Management of MCA Aneurysm Patients. World Neurosurg. 2022 Apr;160:e49-e54. doi: 10.1016/j.wneu.2021.12.083. Epub 2021 Dec 28.
PubMed 34971833
Study at a glance
From the registry record, last updated by the sponsor on 13 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Middle Cerebral Artery Aneurysm Trial: A Randomized Care Trial Comparing Surgical and Endovascular Management of MCA Aneurysm Patients
- ClinicalTrials.gov ID
- NCT05161377
- Acronym / sponsor ID
- MCAAT / PRO-00116285
- Conditions
- Middle Cerebral Artery Aneurysm
- Keywords
- Intracranial aneurysms
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 400 participants (estimated)
- Lead sponsor
- University of AlbertaUniversity, hospital or other
- Study start
- 15 May 2022 (actual)
- Primary completion
- 1 Jan 2036 (estimated)
- Study completion
- 1 Jan 2038 (estimated)
- First posted
- 17 Dec 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Intracranial aneurysms located on the middle cerebral artery (MCA) are considered by many surgeons to represent a distinct subgroup of aneurysms for which clipping may still be the best management option. Most MCA aneurysms are accessible, proximal control can readily be secured in case of rupture, and clip application can typically proceed without requiring the dissection of perforating arteries. In comparison, certain anatomic features of MCA aneurysms such as a wide neck, often including a branch artery origin, frequently render endovascular management more difficult. New endovascular devices were and continue to be introduced to address these anatomic difficulties, including stents, flow diverters, and intra-saccular flow disruptors (ISFDs) such as the WEB. Thus, while most aneurysms are increasingly treated with endovascular methods, many MCA aneurysm patients are still managed surgically, but convincing evidence of which management paradigm is best is lacking.
Detailed description
The subgroup results of ruptured MCA aneurysms taken from ISAT-2 has recently been published. This also suggested that better efficacy could be obtained with surgical management of ruptured MCA aneurysms, with a similar number of residual aneurysms at 1 year in each group (4 surgery, 5 endovascular), but 2 rebleedings from coiled aneurysms (one fatal) and 4 other aneurysms retreated due to growing recurrences discovered on short-term follow-up. Although the ISAT has shown that good-grade, small, anterior circulation aneurysms patients have better 1 year clinical outcomes after being coiled, which was further supported by the Barrow Ruptured Aneurysm Trial (BRAT) study, there are several reasons to suspect that those results do not apply to aneurysms located at the MCA bifurcation. Only 14% of aneurysms in ISAT were on the MCA, likely because lesions in this location were preferentially treated with surgery. Even after selection, the MCA subgroup results were similar for coiling and clipping (RR: 1.01 (0.71-1.45)).
First, the number of selected MCA aneurysm patients included in ISAT was disproportionately small (301/2143 or 14%, as compared to 38% in ISAT-2) and they were recruited between 1994 and 2004, a time when only simple coiling was available. The overall trial result of superior clinical outcomes at 1 year was not confirmed for MCA aneurysms. The clinical primary endpoint of mRS >2 was reached in 39/139 clipped (28.1%, 95% CI:0.21-0.36), and 46/162 coiled patients (28.4%, 95% CI:0.22-0.36).
The suspicion that only selected MCA aneurysm patients were judged eligible for endovascular treatment at the time of ISAT is supported by the pre-randomized BRAT study: Of 61 patients with ruptured MCA aneurysms included between 2003 and 2007, 30 were assigned clipping and 31 coiling. Twenty-one of the 31 (68%) endovascular patients were crossed-over to the surgical arm.15 The Finnish RCT on clipping versus coiling reported only 19 ruptured MCA aneurysms because 59 MCA aneurysm patients were excluded.
If most MCA aneurysms can now be treated endovascularly, clinical results of contemporary technical achievements remain to be properly compared to surgical clipping. In particular, although overall clinical results were similar at one year in ISAT-2, rebleedings and retreatments after endovascular treatment remain worrisome.
The final argument for a new trial dedicated to MCA aneurysms has to do with the eventual interpretation of trial results. ISAT-2 was designed to be, and can still be considered a continuation of the original ISAT trial, with a superiority hypothesis in favor of endovascular treatment. The results presented here suggest that this hypothesis may not be appropriate for ruptured MCA aneurysms. Showing a result for a MCA subgroup that differs from the overall results at the end of ISAT-2 risks being scientifically problematic just as in the original ISAT.
Taken together, the available data and foregoing rationale are sufficient to warrant the conduct of a separate trial of surgical clipping versus endovascular treatment for MCA aneurysms, both ruptured and unruptured. MCAAT will provide a transparent care trial context for clinicians to manage patients with MCA aneurysms.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Surgical management | Active comparator | Procedure: Surgical management |
| Endovascular management | Active comparator | Procedure: Endovascular management |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Patients at least 18 years of age
- At least one documented, intradural, intracranial aneurysm anywhere on the course of the MCA vessel, ruptured or unruptured. An untreated ruptured aneurysm (with delay in diagnosis) which is suspected to have occurred more than 30 days prior to study inclusion will be considered an unruptured aneurysm
- In the case of SAH, WFNS grade 4 or less
- The patient and aneurysm are considered appropriate for either surgical or endovascular treatment by the treating team
Key exclusion criteria (4 listed)
- Patients with absolute contraindications administration of contrast material (any type)
- Patients with AVM-associated aneurysms
- Patients or caregivers unable to provide consent
- Poor grade (WFNS 5) ruptured aneurysms
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Surgical managementSurgical clipping will be performed following randomization according to standards of practice, and under general anesthesia. Aneurysms thought by the treating physicians to require deliberate permanent proximal vessel occlusion, construction of a surgical bypass, or other flow-redirecting treatments that do not directly clip the aneurysm will not be excluded; these aneurysms are expected to be more difficult lesions to manage surgically as well as endovascularly. | Procedure or surgery | Surgical management |
| Endovascular managementEndovascular treatment will also be performed following randomization, according to standards of practice, and under general anesthesia. Details regarding type of coils, use of adjunctive techniques such as balloon-remodeling, stents, flow-diverters, ISFD/WEBs or other innovative devices, as well as post- treatment medical management issues, will be left up to the physician performing the endovascular treatment and initial strategies determined prior to randomization. | Procedure or surgery | Endovascular management |
Primary outcome
Treatment Success
Time frame: up to 5 Years or until death, whichever came first
The primary composite outcome measure is Treatment Success, a 5-part composite comprising: 1) occlusion or exclusion of the aneurysm using the allocated treatment modality; 2) no intracranial hemorrhage during follow-up; 3) no re-treatment of the target aneurysm during follow-up, 4) no residual aneurysm at 1 year; 5) independence (mRS <3) at 1 year.
2 secondary outcomes
The occurrence of an intracranial hemorrhage following treatment
Time frame: Follow-up for 5 Years or until death, whichever came first
Failure of aneurysm occlusion using the intended treatment modality
Time frame: Follow-up for 5 Years or until death, whichever came first
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Mar 2026.
- Derived from this study: PubMed 34971833Darsaut TE, Keough MB, Boisseau W, Findlay JM, Bojanowski MW, Chaalala C, Iancu D, Weill A, Roy D, Estrade L, Lejeune JP, Januel AC, Carlson AP, Sauvageau E, Al-Jehani H, Orlov K, Aldea S, Piotin M, Gaberel T, Gevry G, Raymond J. Middle Cerebral Artery Aneurysm Trial (MCAAT): A Randomized Care Trial Comparing Surgical and Endovascular Management of MCA Aneurysm Patients. World Neurosurg. 2022 Apr;160:e49-e54. doi: 10.1016/j.wneu.2021.12.083. Epub 2021 Dec 28.
- Individual participant dataSharing planned: Yes. Data will be made available upon reasonable request.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Tim Darsaut principal investigator
University of Alberta Faculty of Medicine and Dentistry
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Surgical management and Endovascular management in people with Middle Cerebral Artery Aneurysm, run by University of Alberta at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 13 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Sudeshna Bhattacharyna (7804990974, sbhattac@ualberta.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Treatment Success (time frame: up to 5 Years or until death, whichever came first). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05161377, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Mar 2026.