WSC 2026 | Designing CVST trials: lessons from TO-ACT and advances in catheter technology
Johanna Ospel, MD, PhD, University of Calgary, Calgary, Alberta, Canada, reflects on the lessons learnt from the TO-ACT trial (NCT01204333) of endovascular treatment in patients with severe cerebral venous sinus thrombosis (CVST), which was stopped early for futility. Dr Ospel highlights that the trial was well designed for its time, but catheter technology has since advanced, with larger and cyclic aspiration catheters and more modern thrombectomy devices. She suggests that future trials could use adaptive designs and enrol a narrower, more homogeneous population. This interview took place at the 18th World Stroke Congress (WSC) in Seoul, Korea.
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Transcript
Yeah, I think TO-ACT was really well designed, actually, for the knowledge that was there at the time and the technology that was there at the time. And it was a very pragmatic trial. Now, of course, it was stopped early for futility. Those two things, I think, that I just mentioned have changed specifically. So we have larger aspiration catheters. We have more modern technology in general in terms of mechanical thrombectomy devices, and we have these cyclic aspiration catheters...
Yeah, I think TO-ACT was really well designed, actually, for the knowledge that was there at the time and the technology that was there at the time. And it was a very pragmatic trial. Now, of course, it was stopped early for futility. Those two things, I think, that I just mentioned have changed specifically. So we have larger aspiration catheters. We have more modern technology in general in terms of mechanical thrombectomy devices, and we have these cyclic aspiration catheters. And I think in terms of changing the trial design, so recently we’ve seen many more adaptive trials in the stroke space. Of course, there hasn’t been a big trial since TO-ACT in the CVST space, but I think an adaptive trial design that’s able to kind of narrow or pivot towards the patient population that benefits even while the trial is ongoing with adaptive enrichment rules and such, I think that’s a very promising approach. And I think we also learned from TO-ACT that the criteria for enrollment were relatively heterogeneous. So perhaps, yeah, thinking of more like narrowing the patient population down to a more homogeneous patient population from the get-go that may help. Now, of course, which exact patient population that is, is hard to determine. But I do know a very interesting catheter work from, actually experimental benchtop work from the Aachen group, for instance, where they showed that if both transverse sinuses are occluded, then that’s really when intracranial pressure increases. And that’s when patients are at high risk of hemorrhage, which is a bad prognostic sign. So I think there’s lots to learn from benchtop models and animal models as well. So I think that, for example, would be a very good subgroup to focus on.
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