CIRSE Annual Congress

September 14-18 | Lisbon, Portugal

Patient centered - Science driven

September 14-18 | Lisbon, Portugal

Patient centered - Science driven

September 14-18 | Lisbon, Portugal

September 14-18 | Lisbon, Portugal

September 14-18 | Lisbon, Portugal

Patient centered - Science driven
ProgrammeSneak peeksDistal thrombectomy with aspiration

Distal thrombectomy with aspiration

Three reasons why you cannot miss my lecture

  1. You will learn that the efficacy of endovascular treatment in large vessel occlusion strokes does not automatically account for more distal medium vessel occlusion: risks are higher while benefits are potentially smaller.
  2. I will show you that aspiration as first attempt technique in endovascular treatment of large vessel occlusions appeared to be non-inferior to the stentretriever technique and less costly.
  3. I will discuss how it is is yet unknown whether the above non-inferiority of aspiration in large vessel occlusion strokes is also applicable in medium vessel occlusion strokes.

Prof. Wim van Zwam
Speaker bio 

Add this session to your calendar!

Level 1A evidence for the efficacy of endovascular treatment (EVT) was established in 2015 after the positive results of several randomized clinical trials. [1,2] This evidence concerned large vessel occlusions (LVOs), i.e. the intracranial internal carotid artery and first segment of the middle cerebral artery. Furthermore, the 2015 guideline stated that ‘patients should receive endovascular therapy with a stentretriever’ [3].

Since then, experience, developments and new insights have changed the perspective on EVT.

Thrombectomy with aspiration

Aspiration as a technique to remove the clot from an intracranial artery was already used before the success of stentretriever thrombectomy was shown with overwhelming evidence in several trials [4].

The first randomized controlled trial investigating the efficacy of clot aspiration in the setting of acute ischemic stroke was halted after the publication of the positive thrombectomy trials using mainly or exclusively strentretriever [5]. Unfortunately, they could not confirm efficacy: a signal towards effect was seen, but numbers were too small for statistical significance. Later studies supported the positive signal seen in this first trial and a randomized trial confirmed non-inferiority of aspiration as primary EVT technique compared with stent retriever EVT [6]. Moreover, they showed that EVT with aspiration as first choice is less costly than starting with a stentretriever, even when a considerable part of the aspiration first group needs conversion to stentretriever EVT after failure of aspiration. All these trials concerned LVOs in the anterior circulation and the at that time available aspiration catheters were accustomed to these vessels taking into account that larger bore catheters go with higher aspiration force [7].

Thrombectomy in medium vessel occlusions

Medium vessel occlusions (MeVOs) usually comprise the M2 and M3 segments of the middle cerebral artery, as well as the A2 and A3 and P2 and P3 from the anterior and posterior cerebral arteries. The diameters are smaller than the LVOs and the area affected is smaller which theoretically results in less severe symptoms. With a reported incidence of 16 per 100.000 patient/year and -although less severe- not neglectable neurological symptoms, these MeVOs require adequate acute treatment [8,9].

Despite milder neurological symptoms at presentation, these patients may have poor clinical outcomes if not treated. Excellent functional outcome (mRS 0-1) is only achieved in 50% of patients and, while the recanalization rate after intravenous thrombolysis (IVT) is higher in MeVOs than in LVOs, still fewer than half of MeVOs treated with IVT achieve early recanalization, which is strongly associated with better clinical outcomes [8]. Following the success of EVT in LVOs, it was a logical step to explore its benefit in MeVOs as well. Smaller stentretrievers and aspiration catheters, dedicated for more distal vessels, appeared to facilitate EVT in MeVOs. However, because of a higher risk of complications, mainly vessel perforations in combination with generally milder symptoms and higher recanalization rates of IVT than in EVT for LVOs, it remained unclear whether EVT would benefit patients with MeVO strokes [10]. Several randomized trials are currently ongoing to provide insight if – or which – MeVO stroke patients may benefit from EVT. Most of these trials mandate use of a stentretriever. However, some leave the treatment technique to the discretion of the treating physician, allowing aspiration as first choice.

Thrombectomy with aspiration in medium vessel occlusions

Despite lacking evidence of EVT in MeVO strokes, some publications have already appeared on the comparison between aspiration and stentretriever technique for EVT in more distal vessels [11-15]. Three of these studies showed a slight benefit for using aspiration as first attempt [11,13,15], while the other two did not see a difference in outcomes. One study, from 2017, which found no difference in clinical outcomes noted better technical results (less emboli and higher reperfusion rates) with aspiration [14].

The ongoing trials on EVT in MeVOs may shed a light on efficacy of both techniques. With the aforementioned lower costs associated with aspiration as a frontline thrombectomy technique, equal clinical results may lead to a preference for aspiration. Until the results of those trials are made public, choice of technique will depend on personal preferences of treating physicians.

1a: Distal posterior cerebral artery (P3) occlusion before EVT
1b: After EVT
2a: Distal middle cerebral artery (M2) occlusion before EVT
2b: After EVT


Wim van Zwam

Maastricht University Medical Center, Maastrich/NL

Prof. Dr. Wim H van Zwam is an experienced neurointerventional radiologist at the Maastricht University Medical Center, with a PhD in radiology and an MSc in neurointerventional surgery. He was the PI of the MACCA study on contrast enhanced MRA for cerebral aneurysms, co-PI of the MRCLEAN and MRCLEAN_Late trial ( He chairs the DSMB of Philips’ WETRUST study and of the InExtremis trials (LASTE and MOSTE) and is member of several national and international guideline committees.
Prof. van Zwam is a board member of the European Board of NeuroIntervention (EBNI), a fellow of the European Stroke Organization and of the ESC’s Council on Stroke. He has published more than 200 peer reviewed papers, mainly on ischemic stroke, is a regular lecturer at the ECMINT and EXMINT courses as well as ESNR’s Course in Interventional Neuroradiology and ESO/ESNR/ESMINT Stroke Winter School. He is a reviewer and associate editor of several journals.



  1. Berkhemer OA, Fransen PS, Beumer D, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. The New England journal of medicine. Jan 1 2015;372(1):11-20. doi:10.1056/NEJMoa1411587
  2. Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet. Apr 23 2016;387(10029):1723-31. doi:10.1016/S0140-6736(16)00163-X
  3. Powers WJ, Derdeyn CP, Biller J, et al. 2015 American Heart Association/American Stroke Association Focused Update of the 2013 Guidelines for the Early Management of Patients With Acute Ischemic Stroke Regarding Endovascular Treatment: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association. Stroke; a journal of cerebral circulation. Oct 2015;46(10):3020-35. doi:10.1161/STR.0000000000000074
  4. Jankowitz B, Aghaebrahim A, Zirra A, et al. Manual aspiration thrombectomy: adjunctive endovascular recanalization technique in acute stroke interventions. Stroke; a journal of cerebral circulation. May 2012;43(5):1408-11. doi:10.1161/STROKEAHA.111.646117
  5. Mocco J, Zaidat OO, von Kummer R, et al. Aspiration Thrombectomy After Intravenous Alteplase Versus Intravenous Alteplase Alone. Stroke; a journal of cerebral circulation. Sep 2016;47(9):2331-8. doi:10.1161/STROKEAHA.116.013372
  6. Lapergue B, Blanc R, Gory B, et al. Effect of Endovascular Contact Aspiration vs Stent Retriever on Revascularization in Patients With Acute Ischemic Stroke and Large Vessel Occlusion: The ASTER Randomized Clinical Trial. Jama. Aug 01 2017;318(5):443-452. doi:10.1001/jama.2017.9644
  7. Nikoubashman O, Wischer D, Hennemann HM, Büsen M, Brockmann C, Wiesmann M. Under Pressure: Comparison of Aspiration Techniques for Endovascular Mechanical Thrombectomy. AJNR American journal of neuroradiology. May 2018;39(5):905-909. doi:10.3174/ajnr.A5605
  8. Ospel JM, Menon BK, Demchuk AM, et al. Clinical Course of Acute Ischemic Stroke Due to Medium Vessel Occlusion With and Without Intravenous Alteplase Treatment. Stroke; a journal of cerebral circulation. Nov 2020;51(11):3232-3240. doi:10.1161/strokeaha.120.030227
  9. Liu M, Nasr D, Brinjikji W. The incidence of medium vessel occlusions: a population-based study. Front Neurol. 2023;14:1225066. doi:10.3389/fneur.2023.1225066
  10. Ospel JM, Nguyen TN, Jadhav AP, et al. Endovascular Treatment of Medium Vessel Occlusion Stroke. Stroke; a journal of cerebral circulation. Mar 2024;55(3):769-778. doi:10.1161/strokeaha.123.036942
  11. Abecassis IJ, Almallouhi E, Chalhoub RM, et al. The effect of occlusion location and technique in mechanical thrombectomy for minor stroke. Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences. Aug 18 2023:15910199231196451. doi:10.1177/15910199231196451
  12. Alawieh AM, Chalhoub RM, Al Kasab S, et al. Multicenter investigation of technical and clinical outcomes after thrombectomy for distal vessel occlusion by frontline technique. Journal of neurointerventional surgery. Sep 2023;15(e1):e93-e101. doi:10.1136/jnis-2022-019023
  13. Burel J, Gerardin E, Papagiannaki C, et al. Direct Aspiration versus Combined Technique for Distal Medium-Vessel Occlusions: Comparison on a Human Placenta Model. AJNR American journal of neuroradiology. Apr 2023;44(4):441-446. doi:10.3174/ajnr.A7831
  14. Kim YW, Son S, Kang DH, Hwang YH, Kim YS. Endovascular thrombectomy for M2 occlusions: comparison between forced arterial suction thrombectomy and stent retriever thrombectomy. Journal of neurointerventional surgery. Jul 2017;9(7):626-630. doi:10.1136/neurintsurg-2016-012466
  15. Meyer L, Stracke P, Wallocha M, et al. Aspiration Versus Stent Retriever Thrombectomy for Distal, Medium Vessel Occlusion Stroke in the Posterior Circulation: A Subanalysis of the TOPMOST Study. Stroke; a journal of cerebral circulation. Aug 2022;53(8):2449-2457. doi:10.1161/STROKEAHA.121.037792