Surviving brain stroke: Clot removal may help patients up to 72 hours later, says study

A new study published in The New England Journal of Medicine has found that removing a blood clot from the brain may help some stroke patients recover better, even when treatment begins 24 to 72 hours after symptoms start.

The study found that patients who underwent a procedure to remove the clot had better recovery outcomes after 90 days than those who received medicines and other standard care alone. However, the procedure also increased the risk of bleeding in the brain and death. The findings were published online on October 23, 2026.

“The key is advanced brain imaging, which helps identify patients who still have salvageable brain tissue and may benefit from restoring blood flow. However, the findings should not be interpreted as a reason to delay seeking treatment. The study also reported an increased risk of symptomatic brain haemorrhage and death in the intervention group, underscoring the need for careful patient selection and specialist assessment. The message remains clear: every minute counts and patients should reach a stroke-ready hospital as quickly as possible,” says Dr Vipul Gupta, Director, Neurointerventional Surgery, Sir H. N. Reliance Foundation Hospital, Mumbai. Excerpts:

What Is a Stroke Caused by a Blood Clot?

An ischemic stroke occurs when a blood clot blocks the flow of blood to part of the brain. Without a steady supply of oxygen and nutrients, brain cells begin to become damaged. The effects can include difficulty speaking, weakness or paralysis on one side of the body, problems with movement and, in severe cases, death.

Quick treatment is important because restoring blood flow may help limit the damage. However, some patients reach medical care late, raising questions about whether treatment can still help.

What Is the Clot-Removal Procedure?

The treatment, known medically as mechanical thrombectomy, involves removing a blood clot from a blocked artery in the brain. Doctors guide a thin tube through a blood vessel, usually entering through the wrist or groin, and move it towards the blockage. Special instruments are then used to remove the clot and restore blood flow.

The procedure is an established treatment for certain patients with stroke. However, its benefits when performed more than 24 hours after symptoms begin have been less certain.

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Why Did Researchers Study Treatment After 24 Hours?

The main question was whether patients could still benefit from clot removal several days after a stroke began. Not all brain tissue is damaged at the same rate. In some patients, although a blood vessel has been blocked for many hours, parts of the affected brain may still be saved if blood flow is restored.

Brain scans can help doctors identify these patients. The researchers therefore focused on people whose scans showed that some brain tissue remained potentially recoverable.

How Was the Study Conducted?

The trial was conducted at specialised stroke centres in China and included 336 patients with a blockage in a major artery supplying the front part of the brain.

The patients were divided into two equal groups:

Treatment group: 168 patients received clot-removal treatment along with standard medical care.
Comparison group: 168 patients received standard medical care without the procedure.
The median time between stroke onset, or the last time the patient was known to be well, and assignment to a treatment group was 38.5 hours. Researchers compared the patients’ recovery and safety outcomes after 90 days.

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What Did the Study Find?

Patients who underwent clot removal generally had better functional outcomes after 90 days than those who received standard medical care alone. Researchers assessed recovery by looking at the degree of disability and how well patients could manage everyday activities.

The findings suggest that selected patients may benefit from clot removal even when treatment starts more than a day after their stroke. However, the study does not mean that every patient treated late will recover better or that the procedure guarantees recovery.

What Were the Risks?

The study also found higher rates of serious complications in patients who underwent the procedure.

Bleeding that caused symptoms occurred in 4.8% of patients in the treatment group, compared with none in the standard-care group. The death rate was 6% among patients who received clot removal, compared with 1.8% among those who received standard medical care alone.

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These findings highlight an important trade-off: the procedure was associated with better overall recovery outcomes, but it also carried a greater risk of serious harm.

Does This Mean Stroke Treatment Can Be Delayed?

No. The findings should not be interpreted as a reason to delay stroke treatment. A stroke remains a medical emergency, and patients should seek immediate medical attention if they develop warning signs such as sudden weakness, facial drooping, difficulty speaking or sudden vision problems.

The study examined a specific group of patients who arrived later and whose brain scans showed potentially recoverable tissue. It does not establish that clot removal is suitable for all patients after 24 hours.

Who May Benefit From Late Treatment?

The findings suggest that some patients with a blockage in a major brain artery may benefit from clot removal even 24 to 72 hours after symptoms begin. The key factor is whether brain imaging shows tissue that could still be saved and whether the potential benefits outweigh the risks.

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Doctors must assess each patient individually, considering scan results, the location of the blockage, the extent of brain injury and the patient’s overall condition.

What Happens Next?

The findings add to research into how doctors can treat stroke patients who arrive at hospital outside conventional treatment windows. Further research may help clarify which patients are most likely to benefit from late clot removal and how the risks of bleeding and death can be reduced.