Warfarin Use for the Stroke Patients

According to UT Southwestern Medical Center researchers, most stroke patients who took the anticoagulant warfarin were no more likely than those who did not take the medicine to have a brain bleed during a treatment to remove a blood clot. The findings, published in JAMA, may help clinicians better assess the risk of endovascular thrombectomy (EVT), thereby increasing the pool of patients eligible for this standard stroke treatment.

“Warfarin is a type of blood thinner commonly used to prevent stroke because of heart conditions such as atrial fibrillation. Although not very common, patients taking warfarin may still experience a stroke. In clinical practice, it’s very possible that some physicians may withhold an endovascular thrombectomy because patients have been treated with warfarin before their strokes.

“Our study could increase the number of patients for whom this lifesaving and function-saving surgery would be appropriate,” said study leader Ying Xian, M.D., Ph.D., Associate Professor of Neurology and in the Peter O’Donnell Jr. School of Public Health at UT Southwestern. Dr. Xian is also Section Head of Research, Stroke and Cerebrovascular Diseases in the Department of Neurology at UTSW.

According to the Centers for Disease Control and Prevention, almost 800,000 people in the United States have a stroke each year. The majority of these strokes are ischemic, which means that a clot prevents blood flow to a part of the brain.

The most frequent treatment for acute ischemic stroke is endovascular therapy (EVT), which involves threading tools through blood vessels to remove the clot. However, as Dr. Xian highlighted, EVTs can occasionally produce symptomatic intracranial hemorrhage (sICH), a potentially catastrophic brain bleed. Although warfarin is a known risk factor for bleeding, it has not been shown if the risk of sICH following EVT is increased in stroke patients who have been on the blood thinner.

Dr. Xian collaborated with Eric Peterson, M.D., M.P.H., Professor of Internal Medicine and Vice Provost for Clinical Research at UTSW, as well as colleagues from other medical institutions across the country, to assist address this question. Between 2015 and 2020, they collected data on 32,715 stroke patients who underwent EVT within six hours of the onset of stroke symptoms. The data came from the American Heart Association’s Get with the Guidelines-Stroke registry, which is the world’s biggest registry of stroke patients.

The researchers compared the results of 3,087 patients who used warfarin prior to stroke to the outcomes of 29,628 patients who did not take any blood thinner. They looked at whether patients had sICH within 36 hours of their EVT surgery, a major systemic hemorrhage, or other problems that necessitated additional medical intervention or an extended hospital stay. Complications from additional therapies that reestablished blood flow in the brain, in-hospital deaths, and discharges to hospice care were also tracked.

After controlling for differences in patients taking or not taking warfarin, the researchers discovered no change in the overall risk of sICH or other adverse events in these two groups of patients. Patients having an international normalized ratio (INR) greater than 1.7—a measure of blood clotting tendency in warfarin patients—had a 4% increased risk of sICH.

Dr. Peterson is unsure whether this effect leads to poorer patient outcomes. Except for a higher risk of bleeding, persons with INRs larger than 1.7 were no more likely to die or have worse functional outcomes at discharge than those who did not take warfarin.

“Physicians must evaluate stroke patients on a case-by-case basis to determine whether EVT is appropriate, but our study suggests that taking warfarin alone should not necessarily be a limiting factor,” he added.

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