Stroke: Adding blood thinners to clot-busting drugs not necessary

Share on Pinterest

• About 15 million people around the world have a stroke each year, with about 62% of cases being ischemic strokes.
• The main treatment for ischemic stroke is a clot-busting medication delivered within 3 hours of having a stroke.
• After a stroke, a doctor may prescribe blood-thinning medications to help prevent clots from forming again.
• Researchers from the Washington University School of Medicine in St. Louis, MO, have found that giving blood thinners in conjunction with clot-busting medications when a person has an ischemic stroke did not improve the person’s 90-day outcome.

Researchers report that about 15 million people around the world have a stroke in the course of a year. About 62% of those people will have an ischemic stroke where blood flow to the brain is stopped due to arterial blockages.

A stroke is an emergency — if you or someone is experiencing stroke symptoms, call 911.

The main treatment for an ischemic stroke is a clot-busting medication that breaks up the arterial clots to allow regular blood flow to the brain. This medication must be delivered within 3 hours of the stroke occurring.

After a stroke, a doctor may prescribe blood-thinning medications to help prevent clots from forming again.

Now, scientists from the Washington University School of Medicine in St. Louis, MO, reported on new research at the American Stroke Association’s International Stroke Conference 2024.

Their findings indicate that giving blood thinners in addition to clot-busting medications when a person has an ischemic stroke did not improve the person’s 90-day outcome.

Researchers also found that the combination of blood thinners and clot-busting medication did not increase a person’s risk of bleeding in the brain.

Why researchers looked at the blood thinners and clot-busting drug combo

During either a stroke or a heart attack — when an arterial blockage stops blood from flowing to the heart — doctors may administer clot-busting medications called thrombolytics.

People who have either a stroke or heart attack may also be prescribed a blood thinner to help keep clots from forming and lower their risk of having another one.

According to Dr. Opeolu M. Adeoye, BJC HealthCare Distinguished Professor of Emergency Medicine and chair of the Department of Emergency Medicine at the Washington University School of Medicine in St. Louis, MO, and lead author of the current study, the research team decided to assess what type of effect adding blood thinners to clot-busting medications would have on people with ischemic stroke.

That was because, while treatment with clot-busting medications works for ischemic stroke, about half of treated patients experience disability 3 months after stroke even with this treatment.

“In the setting of heart attacks, adding these blood thinners to clot-busting medications improved rates of opening blood vessels and improved outcomes,” Dr. Adeoye explained to Medical News Today. “We wanted to see if using this approach would also improve outcomes in stroke.”

No improvement of 90-day outcomes

For this study, Dr. Adeoye and his team analyzed results from the Multi-Arm Optimization of Stroke Thrombolysis (MOST) trial, encompassing study participants from 57 medical centers in the United States.

Study participants in the MOST trial had ischemic stroke severe enough that rehabilitation would likely be necessary.

All participants received a standard clot-busting medication within three hours of the stroke beginning. Participants then received either one of two blood thinners — argatroban or eptifibatide — within 75 minutes of administration of the clot-busting medication plus a 2-hour infusion of the blood thinner, or a placebo.

Upon analysis, researchers found the addition of blood thinners to the clot-busting medication did not improve a participant’s level of physical function at 90 days after an ischemic stroke.

For this reason, the MOST trial was stopped in July 2023 after the results of the first 500 study participants out of a planned 1,200 participants and determined it highly unlikely that a benefit would be found if the research was completed.

Positive takeaways for clinicians and stroke patients

Dr. Adeoye said they were surprised by the negative results.

“Reopening clotted blood vessels is the goal with stroke treatment,” he explained. “We had shown in earlier studies that the medications may improve outcomes, so we were surprised when we found no benefit from the treatments.”

”We believe the key difference between MOST and our prior studies is that the prior studies were done in an era before thrombectomy (physically removing clots through a procedure). As such, any potential benefits of the medications were somewhat blunted by the fact that 44% of MOST patients underwent thrombectomy,” he added.

Despite the negative outcome, Dr. Adeoye said there are positive takeaways for scientists when it comes to future research in ischemic stroke treatment.

The study also showed that the two blood thinners used did not significantly increase the risk of bleeding into the brain.

“We have definitely shown that these two medications do not work for improving outcomes and that adding blood thinners to clot-busting medication [does] not increase rates of bleeding into the brain. As we go forward, these findings will inform future research in the area.”

– Dr. Opeolu M. Adeoye

“Bleeding into the brain is the most important safety concern in treating stroke patients with clot-busting medication and/or blood thinners,” Dr. Adeoye added. “We found that adding additional blood thinners did not improve rates of bleeding into the brain. This means that this approach is safe and worthy of further investigation.”

Setting the stage for future studies

After reviewing this study, Dr. José Morales, vascular neurologist and neurointerventional surgeon at Pacific Neuroscience Institute in Santa Monica, CA, told MNT he found the findings very interesting.

“We typically do not give any sort of blood thinners for the first 24 hours after receiving a thrombolytic agent because of the presumed risk of intracranial hemorrhage [bleeding in the brain],” Dr. Morales explained. “But it’s been an open question that hadn’t been tested in randomized clinical controlled trials whether or not there was some safety there.”

“I think [the findings] put it all in perspective for us that although the thrombolytic medications have a short half-life, trying to enhance antiplatelet regimens against the potential risk of residual thrombosis or atherothrombosis is not particularly effective,” he added. “Things to look for in the future will be to look to see if other agents might be used adjunctively and safely.”

MNT also spoke with Dr. Cheng-Han Chen, a board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA, about this study.

Dr. Chen said the parallels between stroke — also called “brain attack” — and heart attack are driving research to see if treatments typically used for heart attacks would also be beneficial treatment for stroke.

“They didn’t find a benefit to these medications, which was unfortunate, but at least they didn’t find any evidence of harm, either,” he continued. “So it remains to be seen whether there are also very specific types of stroke treatments that would involve these medications. I think it would be helpful to study other avenues of drug delivery [… ] [and] it would be great to see other research with other types of blood thinners.”