Late-breaking data from two randomised controlled trials (RCTs) presented at this year’s International Stroke Conference (ISC; 4–6 February, New Orleans, USA) have found mechanical thrombectomy be a safe and effective treatment option in certain patients with ischaemic strokes caused by medium-vessel occlusions (MeVOs). By utilising refined patient selection strategies and purpose-built devices, the ORIENTAL MEVO and DISTALS studies may have breathed new life into the endovascular treatment of more distally located occlusions—12 months after multiple trials suggested the approach carried no significant benefits over the existing standard of care.
“The ORIENTAL MEVO trial indicates potential benefits of endovascular therapy for selected patients—higher NIHSS [National Institutes of Health stroke scale] scores—with MeVOs and DVOs [distal-vessel occlusions], supported by DISTALS, which showed that specialised devices improve reperfusion without increasing symptomatic haemorrhage compared to medical management alone,” commented Urs Fischer (University Hospital Bern, Bern, Switzerland), co-principal investigator for the DISTAL RCT, which was presented at last year’s ISC. “However, with three earlier trials showing neutral results, further research is needed to validate these findings.”
“ORIENTAL MEVO and DISTALS suggest MeVO thrombectomy is not a routine default, but it is not dead,” added Levansri Makalanda (Royal London Hospital, London, UK), an investigator for the ESCAPE-MeVO trial, from which late-breaking data were also shared at ISC 2025. “The signal looks strongest when we select higher-NIHSS, clearly disabling patients rather than broad, low-severity cohorts, which the initial trails fell foul of. DISTALS also underlines the need for distal specific devices to improve safety and technical success. Key open questions are the right selection thresholds and whether adjuncts like intra-arterial lysis—as in CHOICE—will return for selected MeVO cases.”
ORIENTAL MEVO results
Presented by leading investigators Raul Nogueira (University of Pittsburgh School of Medicine, Pittsburgh, USA), Xiao‐Zhong Jing, and Wei Hu (both University of Science and Technology of China, Hefei, China), the ORIENTAL MEVO trial homed in on a more specific patient population relative to prior RCTs in this space, restricting enrolment to MeVO stroke with moderate or higher clinical severity. Nogueira noted that broader inclusion criteria saw earlier trials like DISTAL and ESCAPE-MeVO enrol patients with low NIHSS scores, which has been cited as one of the key reasons for their neutral results with thrombectomy.
ORIENTAL MEVO therefore targeted a population with baseline NIHSS scores ≥6 as well as less frequent usage of intravenous thrombolysis (IVT) therapies, comparing 90-day modified Rankin scale (mRS) scores between MeVO stroke patients presenting within 24 hours from symptom onset who were treated via thrombectomy plus standard medical management versus medical management alone. MeVOs were defined as occlusions of the co- or non-dominant M2 segment, or M3 segment, of the middle cerebral artery (MCA); A1, A2 or A3 segments of the anterior cerebral artery (ACA); or P1, P2 or P3 segments of the posterior cerebral artery (PCA).
This investigator-initiated, prospective, open-label RCT ultimately saw 280 patients randomised to thrombectomy and 283 randomised to medical management across 48 Chinese sites, with a median NIHSS score of 10 being observed and the M2 segment of the MCA representing the most common occlusion site in both groups—although the combined rates of ACA and PCA occlusions exceeded 40%. Additionally, IVT rates were below 40% across both groups, while a final expanded thrombolysis in cerebral infarction (eTICI) score of 2b–3 was achieved in 74.4% of patients treated via thrombectomy.
The trial’s intention-to-treat analysis found that—as per its primary efficacy endpoint of the ordinal shift in 90-day mRS distribution, with scores of 5 and 6 being combined—the median mRS score was 2 in the thrombectomy group compared to 3 in the non-thrombectomy group. However, Jing relayed that a violation of ORIENTAL MEVO’s proportional odds assumption precluded usage of a common odds ratio, meaning that, “as prespecified”, 90-day functional independence (mRS 0–2) became the primary endpoint. On this outcome measure, thrombectomy achieved statistically significant superiority versus medical management (58.6% vs 46.6%, respectively; adjusted risk ratio [aRR], 1.24; p=0.004). The trial also observed no statistically significant between-group difference regarding 90-day mRS 0–2 specifically in those patients with NIHSS scores <8, which corroborates an earlier finding from the negative ESCAPE-MeVO and DISTAL trials.
The secondary endpoints from ORIENTAL MEVO tell a similar story, with the 90-day rate of mRS 0–1 reported as 48.9% with thrombectomy compared to 33.2% in the study’s control arm (aRR, 1.47; p<0.001), while rates of vessel patency on imaging at 24–72 hours post-procedure were 82.1% and 46.2%, respectively, between the two groups. And, while radiological intracranial haemorrhage (ICH) rates were higher with thrombectomy (11.4%) versus medical management (6%) at 24–72 hours, this did not appear to have instigated any major safety concerns in the treatment arm, as mortality (11.1% vs 10.2%, respectively) and symptomatic ICH (4.7% vs 2.2%, respectively) occurred at statistically comparable rates across the study arms.
Delivering the final verdict based on these data, Jing described the magnitude of benefit with thrombectomy in the trial as “substantial”—positing that, for every 100 MeVO stroke patients who underwent the procedure, 54 experienced a less disabling outcome and a further 12 achieved functional independence compared to those who received medical management only, resulting in a number needed to treat (NNT) of just eight. He concluded that thrombectomy therefore appears to be appropriate in “carefully selected” ischaemic stroke patients with smaller, more distal occlusions, but added that future studies incorporating refined imaging-based case selection and standardised procedural approaches will be critical to optimising outcomes for this emerging patient population.
DISTALS trial data
While choices over thrombectomy devices and techniques were left to the discretion of the operators in ORIENTAL MEVO, a key distinction within DISTALS was the specific usage of the investigational Tigertriever 13 (Rapid Medical) stent retriever in every endovascular treatment. At ISC 2026, Rishi Gupta (Wellstar Health System, Marietta, USA) delivered first-time data from this industry-sponsored RCT on behalf of his co-principal investigator Jeffrey Saver (University of California Los Angeles [UCLA], Los Angeles, USA) and their colleagues.
Conducted predominantly in the USA but also at sites in Germany, Belgium and Sweden, the prospective DISTALS trial enrolled a total of 149 patients before ultimately randomising 118 to receive either thrombectomy with the Tigertriever 13 device plus medical management or medical management only within 24 hours of time last known well. Tigertriever 13 is said to have been designed specifically for the treatment of MeVOs and DVOs, with its key features including a low delivery profile, visibility on imaging, and adjustability and flexibility within these more anatomically challenging cases. In 2021, the device received an investigational device exemption (IDE) from the US Food and Drug Administration (FDA) to be evaluated for this indication via the DISTALS RCT.
In addition to its enrolment focusing exclusively on MeVO stroke patients who were ineligible for IVT, another key difference between DISTALS and ORIENTAL MEVO was the former’s usage of a more imaging-focused primary endpoint: successful reperfusion defined as a >50% reduction in substantial hypoperfusion volume between baseline and 24 hours post-randomisation without the presence of symptomatic ICH. DISTALS also restricted enrolment to only include patients with NIHSS scores of 4–24, or NIHSS scores of 2–24 in those with aphasia and/or hemianopia. However, the trial did utilise the same definition for a MeVO stroke as seen in ORIENTAL MEVO, ultimately producing a higher rate of PCA occlusions but a similar rate of M2s compared to the previously presented RCTs in this area.
Across 51 patients in the thrombectomy arm and 47 in the control arm, as per its intention-to-treat analysis, DISTALS demonstrated a dramatic increase in the rate of successful reperfusion without symptomatic ICH in patients treated using Tigertriever 13 (86.3%) versus those who received medical management (27.7%; p<0.001). Additionally, 0% of patients treated with Tigertriever 13 experienced a symptomatic ICH inside 24 hours, with the only symptomatic ICH in the thrombectomy arm occurring in a patient who was erroneously operated on using the larger Tigertriever 17 device (Rapid Medical). Gupta also reported that the onset-to-randomisation time in DISTALS—more than seven hours for both study arms—was substantially higher compared to DISTAL, ESCAPE-MeVO and DISCOUNT.
“These results highlight what is possible when both the device and the trial are designed specifically for distal stroke,” said co-principal investigator Saver via a Rapid Medical press release. “DISTALS was purpose-built for distal stroke, pairing a device engineered for small, fragile vessels with a tissue-based endpoint designed to measure meaningful brain reperfusion.”
Gupta concluded by emphasising that, across a “distinctive” D/MeVO population that was younger and treated later, on average, than those in the aforementioned trials—and that also received no IVT or anticoagulant therapies—DISTALS reached its primary-endpoint goal, suggesting that the Tigertriever 13 device represents a safe and effective option in these relatively common yet underserved stroke cases. The presenter also informed the ISC audience that, subsequently to these 24-hour data, three-month outcomes including mRS and quality-of-life scores will be shared in the near future. Additionally, Rapid Medical is set to pursue full US FDA clearance of Tigertriever 13 based on these results.
“Distal thrombectomy demands dedicated device engineering,” Gupta added. “Most thrombectomy complications occur during retrieval, when excess tension can injure delicate vessels. Tigertriever 13 actively reduces force before and during retrieval, adapting to distal anatomy to minimise vessel stress. The DISTALS results reinforce why distal-first technology matters for patients.”
