ESOC 2026 | Infarct in new territory after EVT: sub-analysis of the IRIS-IPDMA

We did a sub-analysis of the IRIS-IPDMA and we examined infarct in new territory. To begin with, I would like to quickly introduce you to the concept of infarct in new territory. And this was conceptualized and formalized by Mayank Goyal and colleagues like 10 years ago after the HERMES meta-analysis. They described infarct in new territory as a new ischemic lesion that was detected on follow-up imaging that lies in a vascular territory which is not distal to the index occlusion site. So for example if you have a left-sided carotid T occlusion on follow-up imaging a right-sided MCA infarct would be considered infarct in new territory. And in our group, that raised the question whether giving a thrombolytic before endovascular treatment may reduce the rate of infarct in new territory. And that’s what we aimed to assess using the IRIS population. So we did a sub-analysis of the IRIS IPDMA and we used all patients that were included in the six randomized control trials that were participating in IRIS; we had to exclude some patients where imaging data was not centrally available for adjudication and that left us with a population of 2024 patients. And we found that in 2024 patients infarct in new territory occurred in 265, which equals 13% of our population. And when you look at the two treatment arms, we saw that infarct in new territory occurred more often in the group with direct endovascular treatment with 15% compared to 11% in the bridging thrombolysis group. And in our mixed effects logistic regression models, this translated to an odds ratio of 0.71 and the confidence interval from 0.55 to 0.92. And the p-value was also 0.01. In our secondary analysis, we could also show that infarct in new territory was associated with worst functional outcomes at 90 days and also an increased rate of symptomatic intracranial hemorrhage. So to summarize our sub-analysis of the IRIS-IPDMA examining INT, infarct in new territory, we can see that infarct in new territory occurred in 13% of our population, which aligns with previous literature. Intravenous thrombolysis could reduce the rate of infarct in new territory, which suggests that at least part of the benefit associated with giving intravenous thrombolytics before endovascular treatment comes from reducing the rate of INT. INT itself was then associated with a worse functional outcome. However, when you look at the overall effect of intravenous thrombolysis plus endovascular treatment versus endovascular treatment alone in our sub-analysis population, we could again see that adding a thrombolytic was not superior to leaving it away. This suggests that the benefit of a lower INT rate may be offset by competing mechanisms.

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