A newer type of "clot-busting" medication might be safer than the one long used for treating strokes, a preliminary study hints.
Researchers found that among nearly 7,900 stroke sufferers, those treated with the drug -- called tenecteplase -- were less likely to suffer life-threatening brain bleeding as a side effect, compared to those given the standard medication alteplase.
Overall, 3.7% of alteplase patients suffered the complication, known as symptomatic intracranial hemorrhage. That compared with just over 2% of patients given the newer clot-dissolver.
Tenecteplase, sold under the brand-name TNKase, is currently approved in the United States for treating heart attacks. By dissolving the blood clot causing the attack, it can restore normal blood flow to the heart.
Similarly, most strokes are caused by a clot in a blood vessel supplying the brain (what doctors call ischemic stroke). Since the 1990s, alteplase, sold as Activase, has been the standard clot-dissolving drug for treating those strokes.
Tenecteplase is not yet approved by the U.S. Food and Drug Administration for treating stroke. Ongoing clinical trials are looking at how it stacks up against alteplase in terms of effectiveness.
But some medical centers in the United States and elsewhere are already using tenecteplase for stroke. (In the United States, doctors are allowed to prescribe and give FDA-approved medications for conditions other than what's listed on the label.)
Some hospitals have made the switch, because there is already evidence to support using tenecteplase for stroke, said Dr. Steven Warach, lead researcher on the new study.
Past research suggests the drug is at least as good as alteplase in preventing long-term disability after a stroke, said Warach, a professor of neurology at the University of Texas at Austin's Dell Medical School.
There is also evidence that tenecteplase is better at dissolving large clots, he said.
And practically speaking, tenecteplase is much easier to give, said Dr. Joseph Broderick, a volunteer expert with the American Stroke Association.
Alteplase is given by IV, over the course of an hour, he said, while tenecteplase is injected in one large dose that the body breaks down slowly.
That's especially helpful if a stroke patient needs to be transferred to another hospital for further care, said Broderick, who is also director of the University of Cincinnati's Gardner Neuroscience Institute.
He also noted that, right now, tenecteplase is the less costly treatment.
Broderick cautioned, though, that the new findings do not prove that tenecteplase is the safer drug.
The results do not come from a clinical trial that directly tested the clot-busters, he said. They are instead based on patients treated in the real world.
That means there's a risk of "bias," Broderick explained. There may have been differences among the patients, or among the hospitals that used tenecteplase instead of alteplase, that could explain the findings on bleeding risk.
For the study, Warach and his colleagues analyzed data from a registry set up by several hospital systems in the United States, Australia and New Zealand. Some centers have begun using tenecteplase for stroke patients in recent years, while others administer only alteplase.
In all, 6,429 stroke patients received alteplase and 1,462 were given tenecteplase between 2018 and 2021.
Overall, tenecteplase patients were about half as likely to suffer an intracranial hemorrhage, and the difference was larger among stroke sufferers who needed a thrombectomy. That's a procedure in which doctors surgically remove the blood clot causing the stroke -- often because it's particularly large.
Among thrombectomy patients, just under 3% of those given tenecteplase suffered a brain bleed, compared with nearly 7% of those given alteplase.
The findings will be presented Feb. 9 at the American Stroke Association's annual meeting, in New Orleans and online. Studies presented at meetings are generally considered preliminary until they are published in a peer-reviewed journal.
Warach agreed that the findings do not prove tenecteplase is safer. He said the results were actually "a bit of a surprise," since past studies have not shown the drug to carry a lower bleeding risk.
But, Warach said, the study does provide "reassurance" on the safety of tenecteplase for stroke patients.
For the general public, he said, the most important message is this: Learn the warning signs of stroke, and call 911 when they arise. Getting to the hospital quickly is critical, since earlier stroke treatment means a better chance of a good recovery.
Some warning signs of stroke include sudden balance loss, blurred vision, facial drooping and weakness in the arms.
The study received no funding, Warach said. He has received financial compensation from Genentech, which makes both Activase and TNKase.
The American Stroke Association has more on stroke symptoms and treatment.
SOURCES: Steven Warach, MD, PhD, professor, neurology, Dell Medical School, University of Texas at Austin; Joseph Broderick, MD, professor and director, University of Cincinnati Gardner Neuroscience Institute, Ohio, and volunteer expert, American Stroke Association, Dallas; International Stroke Conference, New Orleans and online, Feb. 9, 2022