FIAT Study

Flow diversion in Intracranial Aneurysm Treatment

A Randomized Trial Comparing Flow Diversion and

Best-Standard Treatment- The FIAT Trial


Flow Diversion  in the treatment of “difficult” aneurysms

Recent attempts to promote durable aneurysm obliteration have recognized the potentially beneficial effect of diverting blood flow with low porosity stents or flow-diverters.  The rationale for using flow diverters in the treatment of intracranial aneurysms is to permanently occlude aneurysms by themselves without the addition of coiling. The use of flow diverters may be considered a paradigm shift: a move from aneurysm occlusion vi coil packing of the sac to repair of the parent vessel by addressing the site of weakness that led to aneurysm dilation. Flow diverters have provided reconstructive eradication of lesions untreatable by coil occlusion such as giant carotid or vertebral aneurysms producing mass effects, and are now expanding to more common lesions.

Current indications for flow diversion may include (but are not limited to):

1.      Symptomatic large and giant cavernous carotid aneurysms (with very little risk of intracranial haemorrhage), previously treated with carotid occlusion, with or without bypass surgery.

2.      Symptomatic or asymptomatic large or giant ophthalmic carotid and vertebral aneurysms (with a high risk of rupture), previously treated with coiling with or without stenting, sometimes coiling with parent vessel occlusion, sometimes with surgical clipping.

3.      Fusiform intradural lesions sometimes untreatable by other means, sometimes previously treated by parent vessel occlusion and surgical clipping.

4.      Recurrent or persistent lesions after failed endovascular treatment or surgery, previously treated with new coil materials, stenting, clipping, sometimes parent vessel occlusion.

5.      Patients that are judged nearly impossible to treat using other endovascular or surgical techniques

The greatest concern regarding flow diversion are the thrombo-embolic risks to the parent vessel or the branches jailed by the stent mesh. Another recently recognized complication is the occurrence of aneurysm ruptures and intracranial haemorrhage days to months following flow diversion of previously unruptured aneurysms.


The FIAT trial

The purpose of FIAT is to provide a prudent, controlled clinical context for the use of flow diversion, a promising but yet to be proved beneficial treatment, in the care of patients with difficult intracranial aneurysms. It addresses a true clinical dilemma, whether the use of flow diversion truly offers a safe and more effective alternative to more conventional methods of treatment, including observation.


FIAT is a pragmatic RCT comparing anatomical and clinical results of endovascular treatment with flow diversion to best standard treatment (BST) as judged by participating clinician. The trial includes a registry for eligible but non-randomized flow diversion patients. The comparator treatment may include the most appropriate amongst surgical clipping, parent vessel occlusion, coiling, high-porosity stenting with or without coiling, and conservative management. 344 patients will be enrolled and followed for one year. The primary hypothesis is that FD can increase the proportion of patients experiencing successful therapy, defined as complete or near complete occlusion of the aneurysm in combination with a mRS ≤  2 at 3 months post-treatment, from 75 to 90%.


Contact Info

The FIAT trial is conducted by Dr. Jean Raymond of the Centre Hospitalier de l’Université de Montréal (CHUM) as the Principal Investigator. The trial is already underway at the CHUM-Notre Dame Hospital (Montréal, Quebec).  If you are interested in joining or have any questions, please contact Dr. Raymond, the PI at or Guylaine Gévry, the Project Manager at


You may download the Protocol and the Case Report Forms  below: 

Guylaine Gevry,
Dec 2, 2015, 11:17 AM
Guylaine Gevry,
Dec 2, 2015, 11:13 AM
Guylaine Gevry,
May 20, 2011, 11:28 AM