Two new randomized trials are reopening the question of whether thrombectomy may benefit selected patients with acute ischemic stroke caused by distal or medium vessel occlusions, a population in which earlier studies failed to demonstrate clear clinical benefit.

Mechanical removal of the clot by thrombectomy has transformed the treatment of stroke caused by large vessel occlusion in the last decade, but recent attempts at using this procedure to target clots in the smaller distal arteries have not been successful. Last year, three separate randomized trials failed to show a benefit of thrombectomy in this patient population.

However, data from two new studies suggest this technique may be possible in certain patients or with a new type of device more suitable for access to these smaller arteries.

The findings of both trials were presented at International Stroke Conference (ISC) 2026.

Oriental MeVO Trial

In the ORIENTAL MeVO trial, thrombectomy was associated with better functional outcomes among patients with distal or medium vessel occlusion and moderate-to-severe neurologic deficits.

Raul Nogueira, MD, an investigator in the ORIENTAL MeVO trial and director of the stroke unit at the University of Pittsburgh Medical Center, Pittsburgh, said the study differed from earlier thrombectomy trials in distal and medium vessel occlusion by enrolling patients with more severe neurologic deficits at baseline.

The trial was conducted at 48 centers in China and enrolled 564 patients with medium vessel occlusion stroke, baseline National Institutes of Health Stroke Scale (NIHSS) scores ≥ 6, and presentation within 24 hours of symptom onset.

Patients presenting beyond 6 hours were required to have imaging evidence of salvageable brain tissue. Participants were randomized to thrombectomy plus standard medical management or standard medical management alone.

The median baseline NIHSS score was 10. M2 occlusions accounted for 38% of cases and M3 occlusions for 19%, and 36% of patients received intravenous (IV) thrombolysis. In the thrombectomy group, the median time from last known well to arterial access was 5.3 hours, and successful reperfusion was achieved in 74% of patients.

Results showed that the primary endpoint — functional independence (modified Rankin Scale [mRS], 0-2) at 90 days — was achieved by 58.6% of patients in the thrombectomy group compared with 46.6% of those in the control group.

After adjusting for age, prestroke mRS score, time from symptom onset to randomization, stroke severity, and occlusion site, the risk ratio was 1.24 (95% CI, 1.07-1.44; P = .004).

Substantial Benefit

“The magnitude of benefit was substantial. For every 100 patients treated, 54 had a less disabled outcome than with medical management alone. In addition, 12 more achieved functional independence, giving a number needed to treat of just eight, which is very low,” Nogueira said.

Subgroup analyses showed that all of the benefit of thrombectomy occurred in patients with baseline NIHSS scores ≥ 8. There was no benefit in patients with scores < 8.

“I think this is why we were able to show a benefit,” he told Medscape Medical News. In the three previous randomized trials, enrolled patients generally had lower baseline NIHSS scores — typically in the range of 6-8 — whereas the median NIHSS score in ORIENTAL MeVO was 10, with the majority of patients presenting with scores > 8, Nogueira noted.

He added that demonstrating benefit in distal or medium vessel occlusion is challenging when patients present with mild deficits as outcomes are often favorable regardless of intervention and treatment-related risks may offset any incremental gain.

“Whereas in the ORIENTAL MeVO trial patients had more severe strokes and it was therefore possible to show a benefit that was not outweighed by risks,” Nogueira said.

Nogueira said that benefit from acute reperfusion therapy, particularly when procedural risks are present, appears most likely in patients with at least moderate stroke severity.

Adverse Effects

In terms of adverse effects, symptomatic intracranial hemorrhage (sICH) within 24 hours occurred in 4.7% of thrombectomy patients and 2.2% of control individuals (a nonsignificant difference).

“We do pay a price for thrombectomy,” Nogueira said. There is a higher chance of hemorrhagic conversion or bleeding problems, but these are low numbers, and we showed a dramatic improvement in outcomes in this study, so the price is worth paying,” Nogueira said.

However, because there have been three negative trials of thrombectomy in distal/medium vessel occlusion, and just this one positive trial, conducted exclusively in China, he believes further data will be required.

“The ACC [American College of Cardiology]/AHA [American Heart Association] guidelines have pretty much put a stop on the treatment of these patients with distal/medium vessel strokes, so while this new data is very promising, I think we need more trials for confirmation,” he commented.

Further trials in this patient population are currently ongoing.

Commenting on the ORIENTAL MeVO trial results for Medscape Medical News, Michael Hill, MD, director of the Stroke Unit at the Calgary Stroke Program, Alberta Health Services, Canada, said the study was important in helping to understand the limits of thrombectomy treatment.

“They clearly showed that thrombectomy works in a more severely affected population with distal/medium vessel occlusions but was not effective if the NIHSS was below 8. In addition, patients were treated relatively early (under 6 hours from onset in most cases),” he noted.

DISTALS Trial

The second thrombectomy trial for distal vessel occlusion stroke, DISTALS, was presented in the same ISC session by Rishi Gupta, MD, a vascular neurologist at Wellstar Health System in Marietta, Georgia.

The trial demonstrated high reperfusion rates and acceptable safety outcomes in carefully selected patients treated with a device specifically engineered for smaller vessels.

The study evaluated a low-profile device designed specifically for navigation within distal vessels. Unlike fixed-diameter stent retrievers, the Tigertriever 13 — developed by Rapid Medical for distal medium vessel occlusions — allows manual control of expansion and deflation to better match vessel diameter, a design intended to optimize clot capture while potentially reducing vascular trauma.

The DISTALS trial enrolled 149 patients with distal vessel occlusion stroke who were ineligible for thrombolysis and presented within 24 hours of symptom onset. Patients were assigned to thrombectomy with the Tigertriever 13 device or to medical management alone.

The primary endpoint was a composite measure of efficacy and safety, defined as successful reperfusion at 24 hours without sICH.

This was achieved in 86.3% of patients in the thrombectomy group vs 27.7% of those in the control group (P < .001). Gupta noted that there were no symptomatic ICH events linked to the Tigertriever 13 device.

A Safe and Effective Approach

In the intention to treat analysis there was one sICH but this occurred with an earlier version of the device which was “off protocol.” The rate of sICH was 1.6%, and no cases were observed in the per-protocol analysis, Gupta reported.

He concluded that the Tigertriever 13 represents a safe and effective approach to clot removal in patients with distal or medium vessel occlusion stroke.

Functional outcome data from the trial are not yet available and are expected to be reported later this year.

Commenting on the results of the DISTALS trial for Medscape Medical News, Nogueira said the results were promising, and the safety data were reassuring.

“From a technical standpoint, it looks like this is a step forward. This technology may provide a safer and more effective treatment in comparison with other modalities. But this is a relatively small study, and we still need to wait to see if there was a clinical benefit.”

He also noted that patients in the DISTALS study did not receive IV thrombolysis before thrombectomy which is known to increase ICH risk. “So that exclusion will automatically improve the safety profile in the trial,” he said.

ORIENTAL MeVO was an investigator-initiated trial. Nogueira reported having no disclosures. The DISTALS study was funded by Rapid Medical. Gupta reported acting as a consultant to Rapid Medical.