By Zdravka Poljakovic
Chairs Prof Didier Leys and Prof Peter Schellinger
This interesting and underrepresented topic was introduced with actual data about blood pressure regulation in acute stroke and especially during endovascular procedures. As we miss evidence-based data, we eagerly await results from two studies – DETERMINE and INDIVIDUATE targeting the mean arterial pressure values in stroke and during endovascular procedures.
In any case, what we know by now is that during the procedures not only the modality of anesthesia, but blood pressure maintenance is maybe even more important. We must take into account the pathophysiological differences between higher/lower BP and the state of blood vessels, being recanalized or not. A Society for Neuroscience in Anesthesiology and Critical Care stresses therefore the importance of dedicated teams, as for now techniques are variable and still no consensus on the choice of preferred medications has been made. Especially important is BP management – before, during and after the procedure and in this field, we lack data at all, or we have just low quality of data. We do know about some outcomes if we have increased BP – like the fact that every 10 mmHg increase in the mean BP in the first 24 hours after EVT rises 14% probability of early neurological deterioration, 20% probability of sICH, diminishes 13% probability of favorable functional outcome, and 3 Mo functional improvement and raises 15% probability of all-cause mortality. What we also know analyzing the data of recent 7 studies is that values of BP in the studies varies a lot during the procedure although being more consistent after the procedure. Furthermore, we are aware of importance of increased BP, but also that hypotension can be even more dangerous. In conclusion – we do not know what optimal BP is especially during the endovascular procedures, and we are still awaiting the results of ongoing RCTs.
Use and type of antiplatelet agents and other adjunctive therapies
In acute treatment of ischemic stroke, we have most data about Aspirin and all meta-analysis did not show any other drug being more effective although the studies we cite most date from 1997 (CAST and IST) said prof Roozenbeek in his introduction. Next question is about early administration of ASA in patients treated with alteplase where some studies showed better final outcome but more early hemorrhagic complications. Finally, when we talk about endovascular treatment, we cannot find any RCT on early administration of ASA after TK. We do have observational studies which showed increased risk of sICH but also a better outcome. The use of heparin in early stroke showed the same results. Furthermore, one post-hoc analysis showed that patients who received periprocedural heparin during thrombectomy had better outcomes. Still, the dosage of heparin during the procedure depends on different centers. Therefore, prof Roozenbeek and his group designed the MR CLEAN MED clinical study investigating thrombectomy and use of ASA and/or heparin during the procedure. After a premature determination of the study, the conclusion was that despite some benefit in outcome, hemorrhagic complications overweight the benefits, so that concomitant use of heparin and ASA during thrombectomy is not to recommend.
What is the impact of cerebral microbleed presence in therapeutic decisions?
Prof Cordonnier started the lecture with some data about the incidence of deep and cortical microbleeds which at least 20 – 30% patients have. Although those finding might increase the risk of sICH it does not statistically influence the outcome of any recanalization procedure. According to guidelines, up to 10 known microbleeds are acceptable for thrombolytic treatment. Let us talk about the risk for hemorrhagic complications, she continued – if there are no microbleeds, the risk to develop hemorrhagic complication is 4.4%, with one microbleed the risk raises to 6.5% and with more than ten it is up to the 46.9%. However, we must distinguish between hemorrhage and symptomatic intracerebral hematoma. Microbleeds lead to more hemorrhagic complications but there is no statistical evidence that in those patients the symptomatic ICH is more prevalent after intravenous thrombolysis. Still, guidelines recommend a careful consideration of thrombolytic therapy if the patient has more then ten microbleeds. However, to final decision we must take more factors in charge, prof Cordonnier recommended. She also confirmed this statement with few interesting clinical cases, showing the real-life situation which often do not follow the guidelines. Finally, we have also to take into the consideration that we do know the benefits of reperfusion therapy, but we still do not know the exact risk of microbleeds, as we lack RCTs. Also, there is no recommendation of a need to perform an MRI in order to check the number of microbleeds before thrombolysis. In final thoughts prof Cordonnier suggested that it may be reasonable to skip thrombolysis in patients who have a combination of more than ten microbleeds, obvious small vessel disease and superficial siderosis.
Pre-treament with intravenous thrombolysis before endovascular thrombectomy. Is the benefit worth the risk?
Talking about this question, we have – as we always as clinicians should – answer one question: what is the expected benefit and what is the expected risk of this particular therapy in this particular patient, prof Coutinho stated in the beginning of his talk. He emphasized that guidelines are clear and useful, but our patients can unfortunately be “out” of guidelines. Talking about guidelines, he continued, we have now at least 6 RTCs which confirmed that intravenous thrombolysis must be given to any patient who fulfils the criteria, even if thrombectomy is planned, and that this “bridging” therapy shows even some benefits in comparison to thrombectomy alone. To make it more precise, the studies showed absolute difference in favor of intravenous thrombolysis + endovascular treatment (in outcome, mortality and even in successful reperfusion rate) in spite of the higher risk for sICH. The big advantage will come from the IRIS collaboration, where members of all six trials are working together in order to analyze and discuss more data from mentioned studies, taking into the consideration also some other parameters which are important in clinical practice, like blood pressure, localization of the occlusion, presence of tandem occlusion etc., etc.…Finally, some more data will also come from the new studies with other reperfusion strategies (like new fibrinolytics as Tenecteplase, like intraarterial thrombolysis, treatment in mobile stroke units, or use of neuroprotection). At the end, and for now, we have to work according the results and guidelines which recommend i.v.rTPa for any suitable patient.
Do procedural approaches including selection of catheters, number of passes reduce ICH risk?
The lecture of prof Power dealt with the impact of endovascular approach especially of endovascular techniques, tools, and methods on hemorrhagic complications risk. First topic was about number of passes where several observational studies and sub analysis were presented, with a conclusion that more passes give more risk, and that the “cut-off” number is obviously three passes. Considering first pass effect, the studies showed that any hemorrhage is significantly lower after only first pass, however, sICH incidence showed no difference, being probably due to other factors. The rate of SAH is 5.43 but just 1.84 are symptomatic, and more than three passes increase the risk of SAH as well. Considering the effect of anesthesia on ICH, prof Power emphasized, there is no difference in risk of ICH if general anesthesia or conscious sedation was used, which was confirmed in 5 RCTs. Guiding catheter type did also not influence the risk – which is in overall about 5% – 6% – but it is worth to mention that blind catheter interventional group had less ICH, but also more patients with first pass effect. Considering thrombectomy technique direct aspiration had less hemorrhagic complications. Different types of catheters however did not make a difference. Finally, a very important information came from studies who analyzed risk of hemorrhagic complications after ACI stenting and which came to conclusion that antithrombotic which are routinely given as a prevention of thrombotic incidence did not increase the risk of hemorrhagic complications. So at the end, prof Power could conclude that some factors during endovascular procedure, and especially number of passes, can influence the risk of hemorrhagic complications for the patient.
Discussion was at the end of the session with a number of questions put also on-line. Maybe the most provocative questions were about association between microbleeds and cortical siderosis, or the way of applying i.v. rtPa before and during the endovascular treatment where most of the lecturers agreed to give the full dosage of alteplase even in case of complete recanalization on the angiography. Interesting discussion also developed considering the blood pressure regulation. The conclusion from the chairmen was that the session was very clinically orientated as well as of great benefit for everyday practice and problems which we face in treating acute stroke.