Landmark study may impact standard stroke treatment guidelines

November 11, 2017, Emory University
A blood clot forming in the carotid artery. Credit: copyright American Heart Association

Standard guidelines for stroke treatment currently recommend clot removal only within six hours of stroke onset. But a milestone study with results published today in the New England Journal of Medicine shows that clot removal up to 24 hours after stroke led to significantly reduced disability for properly selected patients.

The international multi-center clinical study, known as the DAWN trial, randomly assigned 206 who arrived at the hospital within six to 24 hours to either endovascular therapy, known as thrombectomy, or to standard medical therapy.

Thrombectomy involves a catheter placed in the femoral artery and snaked up the aorta and into the cerebral arteries where the clot that is blocking the artery, and causing the neurological symptoms, is retrieved.

Almost half of the (48.6 percent) who had clot removal showed a considerable decrease in disability, meaning they were independent in activities of daily living 90 days after treatment. Only 13.1 percent of the medication group had a similar decrease. There was no difference in mortality or other safety end-points between the two groups. 

"These findings could impact countless stroke patients all over the world who often arrive at the hospital after the current six-hour treatment window has closed," says co-principal investigator Raul Nogueira, MD, professor of neurology, neurosurgery and radiology at Emory University School of Medicine and director of neuroendovascular service at the Marcus Stroke & Neuroscience Center at Grady Memorial Hospital.

"When the irreversibly damaged brain area affected by the stroke is small, we see that clot removal can make a significant positive difference, even if performed outside the six-hour window," says co-principal investigator Tudor Jovin, MD, director of the University of Pittsburgh Medical Center Stroke Institute. "However, this does not diminish urgency with which patients must be rushed to the ER in the event of a stroke. The mantra 'time is brain' still holds true."

To select patients for the trial, the researchers used a new approach which used brain imaging and clinical criteria as opposed to just time alone.

"Looking at the physiological state of the brain and evaluating the extent of tissue damage and other clinical factors seems to be a better way to decide if thrombectomy will benefit patients as opposed to adhering to a rigid time window," says Nogueira.

The researchers planned to enroll a maximum of 500 patients over the course of the study period. However, a pre-planned interim review of the treatment effectiveness after 200 patients were enrolled in the trial led the independent Data Safety Monitoring Board overseeing the study to recommend early termination of the trial, based on pre-defined criteria demonstrating that clot removal provided significant clinical benefit in the studied patients.

"Our research and clinical teams are immensely proud of these breakthrough findings, which are so profound they will likely result in a paradigm shift that will not be seen again for many years in the field of therapeutics," says Michael Frankel, MD, professor of neurology, Emory University School of Medicine, chief of neurology and director of the Marcus Stroke and Neuroscience Center for the Grady Health System.

According to Frankel, the Emory neuroscience team was a major contributor to the DAWN trial, working at Grady Memorial Hospital, the second leading site of the trial's enrollment.

The DAWN trial included trial locations in the United States, Spain, France, Australia and Canada. The trial was sponsored by Stryker Corporation, a medical technology company that manufactures the clot removal devices used in the study.

The DAWN trial results were presented at the European Stroke Organization Conference in May.

Explore further: Clot removal therapy effective outside six-hour window for some stroke patients

Related Stories

Clot removal therapy effective outside six-hour window for some stroke patients

May 16, 2017
Results of a randomized controlled trial show that endovascular treatment (ET) to remove a stroke-causing blood clot in the brain is effective in some patients even when performed within 6 to 24 hours after a stroke. Current ...

DAWN of a new day for stroke patients as study promises new options and a wider treatment window

July 26, 2017
Results of the first study showing some acute stroke patients could benefit from neuroendovascular surgery 6 to 24 hours after a stroke will be presented at the Society of NeuroInterventional Surgery's (SNIS) 14th Annual ...

Clinical benefit of clot retrieval now proven up to 24 hours after major ischemic stroke

June 6, 2017
Results of an international, randomized controlled research study show that mechanical thrombectomy, which is an endovascular treatment to remove a stroke-causing blood clot in the brain, is effective in some patients even ...

DAWN results show reduction in disability from stroke up to 24 hours of onset

May 17, 2017
Results from the DAWN stroke trial presented at the European Stroke Organization Conference (ESOC) provide compelling evidence that selected patients suffering a major ischemic stroke recovered significantly better with mechanical ...

Quicker clot removal may lead to better outcomes

February 17, 2016
The faster a blood clot causing a stroke is removed, the less disability a patient may have, according to research presented at the American Stroke Association's International Stroke Conference 2016.

New study 'game-changer' for stroke treatment worldwide

February 11, 2015
A landmark study published in the New England Journal of Medicine today heralds a new era in stroke treatment across the globe.

Recommended for you

Physical activity necessary to maintain heart-healthy lifestyle

September 24, 2018
Exercise and physical activity are of vast global importance to prevent and control the increasing problem of heart disease and stroke, according to a review paper published today in the Journal of the American College of ...

Height may be risk factor for varicose veins, study finds

September 24, 2018
The taller you are, the more likely you are to develop varicose veins, according to a study led by Stanford University School of Medicine researchers that examined the genes of more than 400,000 people in search of clues ...

Prosthetic valve mismatches common in transcatheter valve replacement, ups risk of death

September 24, 2018
In the largest multi-institutional study to date, led by researchers from Penn Medicine, the team found that among patients who underwent a transcatheter aortic valve replacement (TAVR), a high number experienced severe and ...

Study reveals a promising alternative to corticosteroids in acute renal failure treatment

September 21, 2018
A protein produced by the human body appears to be a promising new drug candidate to treat conditions that lead to acute renal failure. This is shown by a study conducted at São Paulo State University (UNESP) in São José ...

Can a common heart condition cause sudden death?

September 20, 2018
About one person out of 500 has a heart condition known as hypertrophic cardiomyopathy (HCM). This condition causes thickening of the heart muscle and results in defects in the heart's electrical system. Under conditions ...

New drugs could reduce risk of heart disease when added to statins

September 20, 2018
New drugs that lower levels of triglycerides (a type of fat) in blood could further reduce the risk of heart attack when added to statins. These new drugs, which are in various stages of development, could also reduce blood ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.