Acute stroke is the third leading cause of mortality and the major cause of long-term disability in the developed world. Ischemic strokes account for about 85 percent of all acute strokes and are caused by clots that block blood vessels in the brain, stopping the flow of blood to crucial brain areas.
The main approach to treating acute ischemic stroke is thrombolysis, which degrades the clot causing the stroke and provides significant clinical improvements. The only thrombolytic intervention for acute ischemic stroke that is currently approved by the U.S. Food and Drug Administration (FDA) is alteplase. However, alteplase must be administered within three hours after symptom onset to avoid the risk of inducing a hemorrhage in the brain. (More recent evidence supports delivering alteplase up to 4.5 hours.)
Because of this time limitation, it is estimated that alteplase is currently administered to less than five percent of acute stroke patients. While this time limitation is a large factor, a high proportion of patients arriving within the appropriate time window still do not receive alteplase due to contraindications (e.g. age, severity, hypertension etc.) or due to the unfavorable risk-benefit ratio.
Recently a new thrombolytic agent, desmoteplase, has been developed that is based upon a protein found in the saliva of the Desmodus rotundus, better known as the common vampire bat. Studies conducted so far suggest desmoteplase breaks down clots efficiently and elicits few side effects, indicating the potential for better clinical outcomes. Importantly, it is possible to administer desmoteplase up to nine hours after symptom onset. Swedish Medical Center is participating in DIAS-4, a new study to assess the safety and effectiveness of desmoteplase.
“This new agent holds great promise,” said William Likosky, M.D., principle investigator for the clinical trial and medical director of the Swedish Acute Telestroke Program. “Currently, we are fortunate to have a network of emergency departments in which alteplase can be administered within an early window. If stroke patients have an initial treatment window up to nine hours, however, we can consider transferring them to medical centers that can provide thrombolysis beyond that available for alteplase.”
This clinical research study to test desmoteplase is being carried out under strict oversight by the FDA. By participating in this study, Swedish continues its tradition of offering the most advanced therapies available to patients who have few other options. In addition, the Swedish Acute Telestroke Program is able to offer this trial to patients outside the Seattle area who are brought emergently to Swedish for treatment.