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Original research
Flow modification on the internal carotid artery bifurcation region and A1 segment after M1-internal carotid artery flow diverter deployment
  1. Federico Cagnazzo1,
  2. Raed Ahmed1,
  3. Pierre-Henri Lefevre1,
  4. Imad Derraz1,
  5. Cyril Dargazanli1,
  6. Gregory Gascou1,
  7. Carlos Riquelme1,
  8. Julien Frandon2,
  9. Alain Bonafe1,
  10. Vincent Costalat1
  1. 1 Neuroradiology Department, Centre Hospitalier Regional Universitaire de Montpellier, Montpellier, Languedoc-Roussillon, France
  2. 2 Radiologie et Imagerie Médicale, Hôpital Universitaire Carémeau, Nîmes, Nîmes, France
  1. Correspondence to Dr Federico Cagnazzo, Neuroradiology Department, Centre Hospitalier Regional Universitaire de Montpellier, Montpellier 34000, France; f.cagnazzo86{at}


Background Clinical and hemodynamic consequences of flow diverters extending from the M1 to the internal carotid artery (ICA), covering the A1 segment, have rarely been investigated. We aimed to provide angiographic and clinical data about flow modifications on the covered A1.

Methods Consecutive patients receiving M1-ICA flow diverters for unruptured aneurysms were collected from our prospective database (2014–2020).

Results 42 A1 arteries covered with a single device were studied. All patients had an angiographic detected contralateral flow from the anterior communicating artery (AcomA). Immediately after flow diversion, 20 (47.6%) covered A1 showed slow flow. During a mean angiographic follow-up of 14 months, 13 (31%) and 22 (52.3%) A1 arteries were occluded and narrowed, respectively. Flow changes were asymptomatic in all cases. Vascular risk factors, sex, oversized compared with not oversized stents, immediate A1 slow flow, age, diameter of the A1, length of follow-up, and platelet inhibition rate were tested as prognosticators of A1 occlusion. Length of the angiographic follow-up was the only predictor of A1 occlusion (p=0.005, OR=3, CI=1.4 to 6.7). There were two device related ischemic events with a 2.3% rate of morbidity (one basal ganglia infarct after coverage of the M1 perforators and one transient acute instent thrombosis).

Conclusions Covering the A1 segment during M1-ICA flow diversion seems relatively safe, if the contralateral flow is assured by the AcomA. Approximately 31% and 52% of the covered A1 showed asymptomatic occlusions and narrowing, respectively. The likelihood of flow modification was proportional to the length of follow-up. Morbidity associated with flow diversion in the ICA terminus region was 2.3%.

  • aneurysm
  • angiography
  • flow diverter
  • intervention

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  • Contributors Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work: FC, ID, JF, CD, P-HL, GG, CR, AB, and VC. Drafting the work or revising it critically for important intellectual content: FC, RA, ID, JF, and VC. Final approval of the version to be published: FC, RA, ID, CD, P-HL, GG, CR, AB, and VC. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved: FC, JF, RA, ID, CD, P-HL, GG, CR, AB, and VC.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial, or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval Ethics approval was not required because all of the data were derived from our approved retrospective hospital database. Due to the retrospective nature of this study, the requirement for informed patient consent was waived.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request.