Open letter looking for ESO bloggers

Since 2016 the European Stroke Organisation has used the ESO Blog as a platform to share news with the European stroke community. It informs the international community about recent publications in the European Stroke Journal and blogs about scientific developments and clinical topics. Besides, the Blog provides coverage about the European Stroke Organisation Conference, informs about ESO workshops, D2D visits, and many more activities . We strongly value the contribution from our ESO members and young stroke physicians and researchers in particular. We believe that their input and social media outreach enforces their position within the international stroke community and contributes to a next generation in European stroke care that is strongly connected.

This fall we are inviting young stroke scientist and physicians who are interested in writing about stroke related topics to contribute to the ESO Blog. The selected candidates will have the opportunity to write blog posts on topics that might be interesting to our readers during the following year and we will recognize their contribution.

We kindly ask you to forward this information to young stroke physicians and doctors who might be interested in contributing to the ESO Blog. Those who are interested can send an example blog post (max 500 words) and their CV to esoinfo@eso-stroke.org before 1 October 2022. For examples of posts and previous topics, please check out the ESO Blog.

Feel free to contact us if you have any questions.

Sincerely,

Diana Aguiar de Sousa
Ellis van Etten

A tough clot: platelet-rich thrombi and efficacy of endovascular therapy

In acute ischemic stroke with large vessel occlusion, the efficacy of endovascular treatment (EVT) depends strongly on the ability to obtain successful recanalization. Complete recanalization after a single EVT pass – known as the first pass effect (FPE) – is associated with the best clinical outcome. Using quantitative assays, the study from Delvoye and his colleagues evaluates the potential link between clot cellular composition and outcome after EVT.

This study collected thrombi from stroke patients and had the recanalization status scored by experienced neuro-interventionalists. Thrombi that weight over 10 mg were lysed with a special homogenization method. Then quantification of red blood cells and white blood cells in the thrombus homogenates was performed by measuring the heme concentration, and DNA content respectively. Platelet content was estimated by measuring GPVI levels in the thrombus homogenates.

The study team retrieved a total of 729 thrombi of which 250 were large enough to be homogenized. Of those 250 thrombi, the median number of passes during EVT was 2 (range 1 – 12) and FPE was achieved in 36%.

Thrombus GPVI levels were significantly different between patients with and without FPE; the mean GPVI content being significantly lower in the first pass effect group. After adjusting for potential confounding factors, including use of IV tPA therapy and occlusion site, a lower CPVI concentration remained significantly associated with first pass effect (OR 0.55 (95% CI 0.39 0 0.79; p <0.001). Higher GPVI levels were also associated with an increased number of passes, a longer reperfusion time, and a lower reperfusion rate. No difference was found in heme and DNA content.

Therefore, they authors conclude that platelet concentration seems to be affecting first pass effect occurrence, as opposed to red blood cell content and white blood cell content. This study strengthens the existing evidence of the association between platelet-rich thrombi and a lower recanalization rate. From a pathophysiologic perspective, this might occur because of increased thrombus stiffness and friction caused by platelets colocalizing with fibrin, neutrophils, neutrophil extracellular traps, and von Willebrand factor. In addition, these factors might also form a stronger resistance to cloth lysis with tPA.

Despite having a certain selection of thrombi in this study, e.g., those obtained after successful EVT and selecting thrombi large enough for being homogenized, the study does detect a significant effect.

In conclusion, this study provides additional evidence of a higher platelets content in thrombi being associated with a lower first pass effect rate and a higher number of passes with EVT. These results might also suggest that adjuvant treatments that target platelets could help improve reperfusion therapy in acute ischemic stroke.

Is blood pressure variability associated with functional outcome after EVT?

It is a well-known fact that the penumbra, viable tissue surrounding the infarct core, is extremely vulnerable to CBF fluctuations, which depend on both local and systemic factors, such as cerebral vasoreactivity, collaterals and blood pressure (BP).

Prasad and colleagues explored how BP variations over time in the first days after endovascular treatment (EVT) of large vessel occlusion (LVO) impact the neurological outcome of stroke patients.

To do so, the authors conducted a multicentric observational study that included 2566 patients with LVO treated with mechanical thrombectomy, engaging 11 comprehensive stroke centers, 5 of which had prospective stroke data registries. Most of them collected data between 2012 and 2019, and one center included data from 2005.

Repeated time-stamped systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) within the time frame of 72 hours post-EVT were gathered from the participating centers, with the goal of addressing BP variability after thrombectomy. The primary outcome was stroke-related disability measured using the modified Rankin Scale (mRS) at 90 days.

Blood pressure variability for SBP, DBP, and MAP was sorted into clusters/trajectories using group-based trajectory modeling and tertile classification. In a second step, the authors used multivariate logistic regression modeling in order to adjust for possible confounders such as patient age, sex, baseline NIHSS, preprocedural ASPECTS, admission MAP, time from last known well to reperfusion, postprocedural TICI score, and the overall number of per patient BP measurements.

In the main analysis, which included a total of 102,030 time-stamped BP measurements and a mean number of 50 recorded BP measurements per patient, almost two thirds of patients were classified as having moderate BP variability. BP variability tended to be higher in first hours after thrombectomy. Most importantly, the results suggest that stroke patients with high BP variability after EVT are at greater risk of an unfavorable functional outcome. The explanation might be in the loss of the brain’s ability to sustain blood flow autoregulation mechanisms after stroke, exposing the penumbra area to deleterious fluctuations in systemic blood pressure.

Moreover, this study reinforces the existing evidence of an association between high systolic BP and unfavorable functional outcome in stroke patients. Interestingly, there was no significant association between BP variability and hemorrhagic transformation or symptomatic intracranial hemorrhage (sICH), which is in accordance with previous investigations, such as the BEST study.

Although this study does not provide a definitive answer on whether increased BP variability after thrombectomy is a marker of disease severity or a contributor to the development of poor outcomes, it has important strengths, including the large cohort size and multicenter design, with assessment of multiple BP parameters and adjustment for various confounders. The use of some retrospective data and lack of information on the anesthetic management and the class, dosage and timing of antihypertensive drugs administered during the procedure and in the aftercare are, nonetheless, relevant limitations.

In conclusion, the results of this study contribute to the understanding of BP variability and functional outcome of patients treated with EVT for acute ischemic stroke due to LVO. Further investigation is needed to identify the ideal candidates for possible interventions directed at reducing BP variability, as well as the timing of intervention.

Hopefully, studies such as BEST-II (NCT04116112), OPTIMAL_BP (NCT04205305), ENCHANTED 2 (NCT04140110) and CRISIS I will bring us closer to a solid conclusion.