Clot-buster meds and mechanical retrieval found to equally reduce disability from some strokes

Removing a clot blocking a medium- or small-sized artery in the brain mechanically is a safe treatment for a common type of stroke; however, it did not lessen disability more than best medical treatment (including clot-busting medication if indicated) alone, according to research presented today at the American Stroke Association’s International Stroke Conference 2025.

An estimated 20–40% of people with ischemic (clot-caused) stroke have a clot blocking one of several medium- or small-sized arteries above the base of the brain (called a medium distal vessel occlusion, or MDVO), explained lead study author Marios Psychogios, M.D. head of diagnostic and interventional neuroradiology at the University Hospital Basel in Switzerland.

“Given the high and rising prevalence of ischemic strokes in aging populations, stroke in medium distal vessels represents a significant and growing health concern,” he said. “While these strokes were traditionally thought to have a favorable prognosis, findings from recent studies suggest that only half of people regain functional independence, underscoring the urgent need for more effective treatments.”

Endovascular therapy is a minimally invasive procedure that uses catheters over which a stent-retriever and/or aspiration catheter is advanced to the occlusion in the brain to retrieve the clot and restore blood flow, preventing further brain damage.

The American Heart Association/American Stroke Association 2019 Guidelines for the Early Management of Patients with Acute Ischemic Stroke recommends mechanical clot removal within 24 hours of symptom onset for selected patients with clots blocking large arteries. For clots blocking medium vessels, the Association notes that “although the benefits are uncertain, the use of mechanical thrombectomy with stent retrievers may be reasonable” for carefully selected ischemic stroke patients within six hours of symptom onset.

The DISTAL trial, launched in 2021, is investigating whether endovascular therapy in addition to best medical therapy—which often includes intravenous clot-busting medications—would reduce disability more than clot-busting treatment alone.

The trial included 543 adult patients who entered one of 55 hospitals with disabling stroke symptoms. Imaging tests confirmed a medium distal vessel blockage in all participants. Participants were randomly selected to receive either standard stroke care with intravenous clot-busting medication if deemed eligible or standard stroke care/intravenous clot busters plus endovascular treatment to remove the clot.

The effectiveness of the treatment was measured by the participant’s disability and need for assistance in daily activities 90 days after the stroke.

At the 90-day follow-up, the analysis found:

• No significant difference in disability in those receiving endovascular therapy plus standard medical care and those receiving standard medical care alone.
• Similar rates of death were noted for each group: 15.5% for those receiving endovascular therapy plus standard medical care vs. 14% among those receiving standard medical care alone.
• Rates of severe (symptomatic) brain bleeds were 5.9% for those receiving endovascular therapy plus standard medical care vs. 2.6% for standard medical care alone.

“Endovascular therapy with the current techniques may not always provide extra benefits, so it could be worth reconsidering it as the standard treatment for medium distal vessel blockages. However, it is a safe option that can still be considered for select people on a case-by-case basis,” said Urs Fischer, M.D. M.Sc., co-principal investigator of the DISTAL trial and director of neurology at the University Hospital Bern in Switzerland.

The lack of added benefit was confirmed when researchers analyzed specific subsets of people, such as those who did not receive intravenous clot-busting medications and those who had more severe strokes. Some people may not receive clot-busting medications because these medications can be harmful to them.

“We were surprised at the overall outcome of the participants, which was worse than we anticipated based on retrospective data,” Psychogios said.

The researchers are currently conducting a detailed analysis of whether endovascular therapy was more or less effective in different subgroups of participants, perhaps enabling them to identify characteristics that might be associated with a more positive outcome following the treatment.

Because almost all participants in the study were white, the results may not be generalizable to other populations. While the study’s design offered the benefit of looking at the real-world application of mechanical clot removal, it may have limited the researchers’ ability to detect positive effects from it that would have been apparent in a more selective patient group, both researchers agree.

In addition, physicians who already believed that endovascular therapy was a superior treatment might have treated patients with endovascular therapy outside of the trial rather than taking the chance that their patients might be randomized to standard medical treatment alone.

“While the results of the DISTAL trial might seem discouraging, we see it as a wakeup call to continue investigating treatment options for medium or distal vessel occlusion patients as outcomes appear to be more severe than expected and evidence-based effective treatment options are still lacking,” Psychogios said.

Study details, background and design:

• The DISTAL (EnDovascular therapy plus best medical treatment (BMT) versus BMT alone for MedIum VeSsel Occlusion sTroke—a prAgmatic, international, multicenter, randomized triaL) study enrolled patients between December 2021 and July 2024, with the final assessment completed in October 2024.
• The study was conducted at 55 sites in Switzerland, Germany, Belgium, Spain, Portugal, Italy, Netherlands, Sweden, Israel, Finland and the United Kingdom.
• The study included 543 patients (44% women, average age 75 years, 98% white) who experienced a clot-caused stroke located in one of the medium- or small-sized arteries in the brain. Before the stroke, 97.9% of the participants lived at home. About 63% had no disability before the stroke, 17% had symptoms but could independently carry out their usual activities, 11.5% could not do all activities but could look after their affairs without assistance, and 8% required assistance for walking and other needs.
• Imaging tests were conducted on all patients to confirm they could be treated within 24 hours of symptom onset. During imaging, blockages were visualized mainly in the M2 (44%) or M3 (27%) segments of the middle cerebral artery or in the P2 (14%) or P1 (6%) segment of the posterior cerebral artery.
• Stroke severity at hospital admission was moderate, with a median score of 6 on the 42-point National Institutes of Health Stroke Scale.
• Participants were randomized to receive either best medical treatment at a dedicated stroke center, including clot-busting medication if indicated (272 participants out of which 66% received clot-busting drugs) or best medical treatment plus endovascular treatment (271 participants).
• Decisions about the exact devices and procedures used for endovascular treatment were left to the treating physician. Participants were excluded if they had a brain bleed, other severe medical conditions, or previous treatment or anatomical features that made endovascular treatment unlikely to be successful.
• The primary outcome was the degree of disability and need for help in daily activities 90 days after the stroke, as measured with the modified Rankin Scale with ratings from 0 (no disability) to 6 (death). Disability was assessed by someone unaware of the treatment received.