This year, 25 October marks a full decade since the initial presentation of results from the MR CLEAN randomised controlled trial (RCT), which—along with multiple other RCTs—instigated the rapid expansion of mechanical thrombectomy in the treatment of acute ischaemic stroke. Here, two of MR CLEAN’s leading clinical investigators, Charles Majoie (Amsterdam, The Netherlands) and Diederik Dippel (Rotterdam, The Netherlands), reflect on the impact of the study and outline remaining areas for improvement regarding thrombectomy treatments.
Within a decade, the landscape of acute stroke treatment has changed drastically. Looking back now, to when it all began at the 9th World Stroke Congress (WSC; 22–25 October 2014, Istanbul, Türkiye), shows that much has been done and changed, and many patients have benefitted—but we are not finished yet!
Here, we present a historical summary and also a global overview of the availability of this highly effective treatment for ischaemic stroke.
Evolution of EVT
Before 2014, thrombectomy—or endovascular therapy (EVT)—was performed in selected cases, mostly under research protocols or in major stroke centres. The MR CLEAN trial helped to change that by providing high-quality evidence, prompting rapid adoption in clinical practice. By 2015, after MR CLEAN and subsequent trials, EVT became part of routine stroke care guidelines, resulting in significant global growth.
The pivotal MR CLEAN trial was first presented at WSC on 25 October 2014, marking a turning point in the treatment of ischaemic stroke. This groundbreaking study highlighted the benefits of EVT for large vessel occlusion (LVO) strokes, and it paved the way for global changes in stroke management.
MR CLEAN was published in the New England Journal of Medicine in January 20151, followed by publication of six other landmark trials: ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT, THRACE and PISTE, and an individual patient data meta-analysis.2 These trials confirmed the efficacy of EVT in treating acute ischaemic stroke, solidifying its place as the standard of care. The profound impact of these studies is evidenced by widespread citations and recognition in stroke literature.
Over the past decade, the indications for EVT have expanded significantly. Initially limited to LVO within 0–6 hours of stroke onset, it now encompasses treatment windows extended to 24 hours, and patients with small to large infarcts.3 Treatment is no longer confined by age or certain preexisting conditions, making EVT a viable option for a broader range of stroke patients.
The expanded eligibility criteria for EVT—including patients presenting up to 24 hours after stroke onset and those with more extensive infarcts—has dramatically increased the number of potential candidates for the procedure. This has also contributed to the surge in thrombectomy numbers worldwide.
In 2016, roughly 30,000–40,000 thrombectomies were performed across the globe. By 2020, this number grew substantially to more than 100,000 annual procedures, driven by better access, expanded treatment windows, and the broadening criteria for patient eligibility. For 2022–2023, estimates suggest over 150,000 EVT procedures globally per year, with regions like North America and Europe accounting for a large proportion of these numbers.4
However, despite this remarkable growth, the lack of adequate facilities and trained professionals in many regions continues to hinder global access to thrombectomy, reinforcing the need for further expansion efforts.
Global access disparity
The number of interventions performed worldwide has skyrocketed—but disparities in access remain. While developed regions benefit from widespread implementation of EVT, many lower-resource countries still face challenges in providing this life-saving treatment. Such a gap calls for increased efforts in infrastructure development and training to make EVT more universally available.
Developed regions—including North America, Western Europe, Australia and parts of Asia like Japan and South Korea—have seen a more uniform increase in thrombectomy rates due to established infrastructure, access to stroke care centres, and trained interventionists. In contrast, many low- and middle-income regions and countries still have limited access to EVT, despite growing recognition of its importance. This leads to considerable variation in thrombectomy availability across the world.
In recent years, China and India have made efforts to scale up thrombectomy services, given their large populations and increasing burden of stroke. This can be seen with the increased number of thrombectomies in China, rising from 20,000 in 2019 to 72,000 in 2023. But, although growth has been rapid, these countries are still catching up in terms of the ratio of thrombectomy procedures relative to stroke incidence. In 2023, in India, only 4,500 out of 375,000 patients who qualified for stroke intervention received this life-saving treatment.
Further challenges
The success of acute thrombectomy has highlighted the need for adequate post-intervention stroke unit care and basic rehabilitation, in order to make the effect of the treatment sustainable. Stroke unit care benefits more patients, and its overall health impact—on a population level—is at least as significant as the effect of thrombectomy.
The increasing demand for thrombectomies has also placed a significant burden on interventional teams, leading to an increased risk of burnout. The intensive nature of EVT procedures, combined with the critical urgency of stroke care, has underscored the need for better workforce support, including improved work-life balance, team expansion, and mental health resources.
In addition, with expanding indications, there is a growing need for refined patient selection to ensure that EVT is used optimally. The MR PREDICTS tool represents a promising selection algorithm that could help clinicians identify patients most likely to benefit from thrombectomy, potentially improving outcomes and streamlining decision-making.5,6
Looking ahead, the key focus must be on increasing EVT availability, particularly in underrepresented regions and countries. Initiatives should focus on building capacity, training more interventionists, and enhancing stroke care infrastructure, including prehospital triage and stroke unit care in underserved areas to ensure that all patients—regardless of location—can access this life-saving treatment and benefit from it in a sustainable way.
References:
- Berkhemer O A, Fransen P S, Beumer D et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med. 2015; 372(1): 11–20.
- Goyal M, Menon B K, Van Zwam W H et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet. 2016; 387(10029): 1723–31.
- Nguyen T N, Abdalkader M, Fischer U et al. Endovascular management of acute stroke. Lancet. 2024; 404(10459): 1265–78.
- Rai A T, Link P S, Domico J R. Updated estimates of large and medium vessel strokes, mechanical thrombectomy trends, and future projections indicate a relative flattening of the growth curve but highlight opportunities for expanding endovascular stroke care. J Neurointerv Surg. 2023; 15(e3): e349–55.
- https://mrclean-trial.org/mr-predicts.html.
- https://www.contrast-consortium.nl/mr-predicts.
Charles Majoie is a professor of neuroradiology at the Amsterdam University Medical Centers (UMC) in Amsterdam, The Netherlands.
Diederik Dippel is a neurologist and professor of neurovascular diseases at the Erasmus Medical Center (MC), and co-director of the Erasmus MC Stroke Centrum, in Rotterdam, The Netherlands.
