Endovascular Therapy Eyed For Milder Strokes, Later Time Window

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Two randomized trials in China reported better functional outcomes when endovascular therapy (EVT) was added to medical care for selected patients with mild large-vessel strokes or salvageable brain tissue 24 to 72 hours after onset. The results also included procedure-related complications in the mild-stroke trial and higher rates of symptomatic brain bleeding and death in the later-window trial; further research is underway.

Two randomized trials conducted at Chinese stroke centers found that endovascular therapy (EVT) combined with medical care was associated with better functional outcomes for selected patients with mild large-vessel strokes and for patients treated 24 to 72 hours after symptom onset. The findings, published in the New England Journal of Medicine, also raised safety concerns, including serious procedural complications, symptomatic brain bleeding and deaths.

In MILD-MT, researchers randomized 304 people with mild anterior-circulation ischemic strokes and substantial at-risk tissue on imaging to EVT plus medical management or medical management alone. The primary analysis included 300 people. At 90 days, 69.4% of the EVT group had an excellent functional outcome, defined as a modified Rankin Scale score of 0 or 1, compared with 50.0% of the control group. The reported odds ratio was 2.32, with a 95% confidence interval of 1.41 to 3.81.

Symptomatic intracranial hemorrhage within 48 hours occurred in three patients in each MILD-MT group. One death occurred in the EVT group. Serious procedure-related complications were reported in 13.2% of EVT recipients; the most common included arterial dissection, subarachnoid hemorrhage and embolization in a new territory. The editorial accompanying the trials also highlighted less neurological deterioration within seven days among EVT patients: 13.9%, compared with 31.4% in the control group.

In LATE-MT, patients had an anterior-circulation large-vessel occlusion and imaging evidence of salvageable brain tissue 24 to 72 hours after symptoms began. EVT plus standard medical care was associated with better functional outcomes than standard care alone, with a reported common odds ratio of 1.74 (95% CI 1.19-2.55). However, symptomatic intracranial hemorrhage occurred in 4.8% of EVT patients and none of the control patients. Death by 90 days was reported in 6.0% of the EVT group and 1.8% of controls.

Extending Stroke Treatment Eligibility

The studies address two groups that have not been as firmly established as candidates for EVT: people whose initial stroke symptoms are mild despite a large-vessel blockage, and people who arrive well beyond the conventional treatment window. A blocked artery can still threaten brain tissue in these cases, but treatment may carry risks. The reported outcome differences suggest some carefully selected patients could benefit; they do not establish that EVT should be used routinely for everyone with mild symptoms or for all patients presenting late.

The safety results matter to treatment decisions. MILD-MT reported serious procedure-related complications, while LATE-MT had higher observed rates of symptomatic bleeding and death in the EVT group. The studies therefore offer evidence of possible functional benefit alongside harms that need to be weighed, rather than a simple expansion of eligibility. An editorialist described the findings as important advances, while emphasizing caution about antithrombotic treatment in late-window cases.

How the Trials Tested New Groups

EVT uses a catheter-based procedure to remove a clot from a blocked brain artery. For nearly a decade, the established treatment window for anterior-circulation large-vessel occlusion extended to 24 hours from the time a patient was last known to be well. Earlier in 2026, U.S. stroke guidance expanded eligibility in other settings, including some patients with larger ischemic cores and basilar artery occlusions, based on newer evidence.

MILD-MT enrolled patients at 26 comprehensive stroke centers in China during 2024 and 2025. Participants had mild symptoms and imaging showing substantial tissue at risk; their median NIH Stroke Scale score was 4. LATE-MT was conducted at 35 centers and tested treatment in patients with salvageable tissue identified by imaging 24 to 72 hours after onset. Both were multicenter, open-label randomized trials. The editorialist, Gaultier Marnat of Bordeaux University Hospital, cautioned that results in non-Asian populations remain uncertain, in part because causes of large-vessel stroke can differ.

Who Benefits Without Added Harm?

The trials do not resolve whether their findings apply to patients outside the selected study groups, or to populations whose stroke causes may differ. Marnat specifically said outcomes in non-Asian populations require further study. The trials also leave uncertainty about how to balance the functional gains against the observed harms, particularly the bleeding and mortality differences in LATE-MT.

Some features of the studies complicate interpretation. MILD-MT had differences between groups in the proportions with previous stroke or transient ischemic attack and in the use of intravenous thrombolysis. In LATE-MT, thrombolysis and early antithrombotic treatment may be relevant to the bleeding signal, but the available report does not establish that they caused it. The findings do not show that EVT caused every observed difference, and they do not provide a basis for treating all patients in either category.

Further Trials Will Add Evidence

Two ongoing studies are expected to provide additional evidence: MOSTE in France and SELECT LATE in the United States. Their results may help establish whether the benefits and risks seen in the Chinese trials hold in other populations and treatment settings. Until those data are available, decisions about EVT for mild strokes or beyond 24 hours remain dependent on patient selection, imaging findings and clinical judgment.

The reports also leave practical questions for future research, including which imaging features best identify patients likely to benefit and how to manage medications that may affect bleeding risk around late-window procedures. No results or completion dates for the ongoing trials are specified in the source report.

Key Questions

What did the two trials find?

MILD-MT and LATE-MT both reported better functional outcomes with EVT plus medical care than with medical care alone in their selected patient groups. Each also raised safety concerns, with different signals in the two trials.

What does “mild stroke” mean in MILD-MT?

The study enrolled people with mild anterior-circulation ischemic stroke symptoms and a large-vessel blockage, along with substantial at-risk tissue on perfusion imaging. The median NIH Stroke Scale score at baseline was 4.

How late after stroke onset did LATE-MT test EVT?

LATE-MT included patients with salvageable brain tissue identified by imaging 24 to 72 hours after symptom onset. The findings apply to the trial’s selected patients and do not establish that all late-presenting patients should receive EVT.

What safety concerns were reported?

MILD-MT reported serious procedure-related complications in 13.2% of EVT patients, though symptomatic brain bleeding was recorded in three people in each group. In LATE-MT, symptomatic intracranial hemorrhage and 90-day deaths were more frequent in the EVT group than in controls.

What evidence is still expected?

The MOSTE and SELECT LATE trials are ongoing in France and the United States. Their results may clarify how well the findings apply beyond the Chinese trial populations and how benefits compare with risks.

Source: rss