Aurora Semerano, MD

European Stroke Organisation-World Stroke Organization 2020 Virtual Conference
November 7-9, 2020

The Controversy sessions in the ESO-WSO 2020 Conference are intriguing live Q&A sessions focused on grey zones in real-world stroke care, with stroke experts defending their points of view and facing each other in interesting rounds of discussion. On the first day of this ESO-WSO 2020 Conference, the session addressed the following hot topics about endovascular thrombectomy.

Do We Need Perfusion Imaging to Guide MT In Extended Time Window?

YES: Götz Thomalla (Germany) presented the pros of using advanced perfusion imaging for patient eligibility to mechanical thrombectomy (MT) in the extended time window (>6h from onset). He invited us to remember that, first of all, we should rely on current evidence. According to the evidence, whereas perfusion techniques are not required in the early time window, the DAWN and DEFUSE III clinical trials firmly base on advanced imaging for patient selection in the late time window. As a consequence, also AHA/ASA guidelines, ESO consensus, and ESMINT guidelines recommend advanced imaging for patient eligibility. He also pointed out that we cannot reliably trust the ASPECTS score for estimating viable tissue. In addition, against the opinion that perfusion techniques are time-consuming and difficult to interpret, Prof. Thomalla reassured that just a few minutes are needed to perform reliable perfusion imaging and that simple parameters are required for map interpretation: Tmax> 6 seconds identifies penumbra and CBF<30% works for infarct core. This little extra time is well invested to effectively guide reperfusion treatments.

NO: Mayank Goyal (Canada) entered the ring claiming that we do not really need “fancy colour maps” to treat patients with MT in the late time window. He invited us to note that no subgroup of patients demonstrated sure absence of benefit from MT in the analyses of the HERMES collaboration, as well as to focus on the poor natural history of control patients from the DAWN, DEFUSE III, and ESCAPE trials. The 6-hour cut-off derives from an arbitrary selection, while it does not reflect the individual progression of ischemia. Moreover, reliable gold standards are currently missing to identify to what extent brain tissue is infarcted or still viable, and there are sometimes discrepancies between final stroke volume and clinical outcome. Whereas the ASPECTS score may be, in some cases, a struggle to read, the suggestion is to combine it with collateral evaluation on multiphase CTA. According to Prof. Goyal, compared to perfusion imaging, the CT+mCTA combination strategy results in more eligible patients and currently constitutes a trade-off between information and speed, availability and robustness. The final message of Prof. Goyal is clear. Simplifying decision-making is the key to help as many patients as possible: Avoid over-selection and analysis paralysis.

Patients with Severe Stroke Should be Directly Transferred to an Interventional Center (Bypassing Smaller Non-Interventional Centers)

YES: According to Blanca Fuentes (Spain), the “direct transfer to mothership” paradigm carries several advantages compared to the “drip and ship” model. By means of an animation tool of simulation (based on data of STRATIS investigators), Prof. Fuentes showed that intravenous thrombolysis would be only modestly delayed by 13 minutes, while MT would be performed 87 minutes sooner if patients were directly routed to a comprehensive stroke center. A second argument is that this is a cost-saving strategy at a population level since repetition of imaging is avoided. Moreover, it is calculated that patients under the mothership referral model are 2.5 times more likely to receive MT. She also depicted the local experience with the pre-hospital Madrid-Direct Referral to Endovascular Center (M-DIRECT) scale, which evaluates clinical examination, systolic blood pressure, and age. In a few words, patients with severe stroke should be directly transferred, and effective pre-hospital scales can also help in avoiding overload of comprehensive stroke centers.

NO: Marios Psychogios (Switzerland) presented the cons of the “direct transfer to the mothership” paradigm. Patients needing intravenous thrombolysis are much more compared to patients eligible to MT, and treatment delay should be avoided. Pre-hospital scales are still poorly reliable according to Prof. Psychogios, and one useful effort should be focused in speeding up the workflow for tPA administration in the primary stroke centers. Some alternative solutions (other than “direct to mothership” and “drip and ship” paradigms) exist too. The use of Mobile Stroke Units (MSU) in the management of acute stroke patients brings both imaging and thrombolysis to patients in the field, speeding up the timing for tPA administration, and likely helping also in thrombectomy referral. Moreover, an innovative proposal to consider is the one of moving the neuro-interventionist to the primary stroke center, in the so-called “drip and drive” model. A final summary from Prof. Psychogios’ speech could be: “don’t miss the forest for the tree.”

Acute Intracranial Stenting Should be Performed as Rescue Treatment in Failed Recanalization

YES: Rene Chapot (Germany) presented the arguments in favour of acute intracranial stenting as rescue treatment in failed recanalization. He moved from analyzing the relationship between reperfusion degree and recovery: The lowest TICI scores are almost invariably associated with unfavourable outcomes, suggesting that no good results are expected if the vessel is not re-opened. In this setting, rescue intracranial stenting might be the only treatment option to achieve a permanent recanalization and a better outcome. This is an even more relevant issue in the Asiatic population, which has a higher prevalence of intracranial atherosclerosis. Whereas differentiating between a residual thrombus and an atherosclerotic stenosis can be challenging, a series of recent retrospective studies have shown that rescue stenting may be associated with a better functional outcome at 3 months. After different combinations of stent retriever and thrombo-aspiration attempts have been considered, rescue stenting is an option. When MT fails, it’s worth a stent.

NO: Phil White (UK) had a different opinion: Acute intracranial stenting should not routinely be performed as rescue treatment in every case of failed recanalization. So, when to perform it? It depends. Deeply analyzing patient characteristics from the five recent retrospective studies on this theme, it emerges that patients who are likely to benefit from a rescue stenting procedure are young, with moderate though not severe NIHSS, and good premorbid conditions. It should be carefully considered that rescue stenting is associated with high rates of sICH, and risk increases when double antiplatelet treatment is established after tPA administration, in case of large infarcts and/or with the suspicion of SAH and vessel perforation. Whereas a rescue stenting procedure is reasonable if performed early, in a young patient with good ASPECTS and a favorable collateral profile, the same procedure may turn unwise if an acceptable TICI score has already been achieved or whether the risk profile of the patient is unfavorable. The final message? It can be done, but carefully select your patient.