ESOC 2026 | IVT plus EVT versus EVT alone: individual-participant data meta-analysis by the IRIS collaboration

To fully grasp the picture, I would like to go back in time for about 20 years. Back then, the cornerstone for treatment of acute ischemic stroke in patients with a large vessel occlusion in the anterior circulation had received intravenous thrombolysis as the main treatment. Around 2014-2015, the first trial proved that the endovascular treatment is really effective for treating these patients. But you need to note that in these trials, the thrombolysis has always been a part of the therapy. So EVT, or endovascular treatment, was regarded as an addition to IVT, but not really as a replacement. So unlike the cardiologists who really tried to show that PCI is the primary treatment for myocardial infarction, they got rid of the intravenous thrombolysis, the stroke neurologists really grabbed onto the thrombolytics. So in the HERMES meta-analysis, which pooled data from all these trials proving that endovascular treatment was very effective, there was actually a subgroup of patients who did not receive intravenous thrombolysis before thrombectomy. And the very interesting result was of this subgroup analysis that in these patients, the effect estimate was very similar to the whole group. So, of course, that sparked the question whether there really is an added benefit of giving intravenous thrombolytics before thrombectomy in the patients that admit directly to a comprehensive stroke center which is capable of doing an endovascular treatment. And this is why, over the following years, several trials have addressed this question and they have compared direct endovascular treatment to the combination of bridging thrombolysis plus endovascular treatment. In total, it was six trials, and the first two trials were Chinese trials, DirectMT and DVT, and they could actually show that direct endovascular treatment was indeed non-inferior to the thrombolysis approach. However, the subsequent four trials failed to corroborate these previous results and of course this left some question marks in the community. After that, the IRIS collaboration was formed and they pooled data from all six randomized controlled trials and they performed an individual participant data meta-analysis on this very question. In the IRIS main analysis, the pre-specified non-inferiority margin of point A2 could again not be met, which means that non-inferiority of direct thrombectomy could again not be shown. However, very interesting was also that in a nested superiority test, they could also not show that adding the thrombolytic was really superior to leaving it away. So rather than a definitive answer, the IRIS meta-analysis could really show the complexity of the whole topic. And there were several subsequent sub-analyses of IRIS, and I would like to highlight just one. And it was a sub-analysis that investigated timing. So it was shown that the benefit associated with giving the thrombolytic before thrombectomy was time-dependent. So, IVT was effective in the first two hours and 20 minutes. So, to summarize the IRIS-IPDMA, we can conclude that they failed to show non-inferiority of direct endovascular treatment compared to the bridging thrombolysis approach, but it’s also noteworthy that the superiority of adding the thrombolytic was not given compared to leaving it away.

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