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Objective:The objectives of this study were to measure the global impact of the pandemic on the volumes for intravenous thrombolysis (IVT), IVT transfers, and stroke hospitalizations over 4 months at the height of the pandemic (March 1 to June 30, 2020) compared with two control 4-month periods.Methods:We conducted a cross-sectional, observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers. Diagnoses were identified by their ICD-10 codes and/or classifications in stroke databases.Results:There were 91,373 stroke admissions in the 4 months immediately before compared to 80,894 admissions during the pandemic months, representing an 11.5% (95%CI, -11.7 to - 11.3, p<0.0001) decline. There were 13,334 IVT therapies in the 4 months preceding compared to 11,570 procedures during the pandemic, representing a 13.2% (95%CI, -13.8 to -12.7, p<0.0001) drop. Interfacility IVT transfers decreased from 1,337 to 1,178, or an 11.9% decrease (95%CI, -13.7 to -10.3, p=0.001). Recovery of stroke hospitalization volume (9.5%, 95%CI 9.2-9.8, p<0.0001) was noted over the two later (May, June) versus the two earlier (March, April) pandemic months. There was a 1.48% stroke rate across 119,967 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.3% (1,722/52,026) of all stroke admissions.Conclusions:The COVID-19 pandemic was associated with a global decline in the volume of stroke hospitalizations, IVT, and interfacility IVT transfers. Primary stroke centers and centers with higher COVID19 inpatient volumes experienced steeper declines. Recovery of stroke hospitalization was noted in the later pandemic months.

Rapid reperfusion of the entire territory distal to vascular occlusions is the aim of stroke interventions. Recent studies defined successful reperfusion as establishing some perfusion with distal branch filling of <50% of territory visualized (Thrombolysis In Cerebral Infarction “TICI” 2a) or more. We investigate the importance of the quality of final reperfusion and whether a revision of the successful reperfusion definition is warranted. We retrospectively evaluated a prospective database of anterior circulation strokes treated using stentrievers to assess the quality of final reperfusion using two scores: the traditional TICI score and a modified TICI score. The modified TICI score includes an additional category (TICI 2c): near complete perfusion except for slow flow or distal emboli in a few distal cortical vessels. We compared different cut-off definitions of reperfusion (TICI 2a–3 vs. TICI-2b–3 vs. TICI 2c–3) using the area under the curve to identify their correlation with a favorable 90-day outcome (mRS≤2). In our cohort of 110 patients, 90% achieved TICI 2a-3 reperfusion with 80% achieving TICI 2b-3 and 55.5% achieving TICI 2c-3. The proportion of patients with a favorable 90-day outcome was higher in the TICI 2c (62.5%) compared to TICI 2b (44.4%) or TICI 2a (45.5%) but similar to the TICI 3 group (75.9%). A TICI 2c-3 reperfusion had a better predictive value than TICI 2b-3 for 90-day mRS 0–1. Defining successful reperfusion as TICI 2c/3 has merits. In this cohort, there was evidence toward faster recovery and better outcomes in patients with the TICI 2c vs. the traditional TICI 2b grade.

Cardiovascular diseases are major causes of morbidity and mortality in developed countries. Cerebrovascular diseases, especially stroke, represent major burden of disability and economy impact. Major advances in primary and secondary prevention and therapy are needed in order to tackle this public health problem. Our better understanding of pathophysiology is essential in order to develop novel diagnostic and therapeutic tools and strategies. microRNAs are a family of important post-transcriptional regulators of gene expression and their involvement in the pathophysiology of cerebrovascular diseases has already been reported. Moreover, microRNAs may represent above-mentioned potential diagnostic and therapeutic tools in clinical practice. Within this chapter, we briefly describe basic epidemiology, aetiology and clinical manifestation of following cerebrovascular diseases: extracranial carotid atherosclerosis, acute stroke, intracranial aneurysms and cerebral arterio-venous malformations. Further, in each chapter, the current knowledge about the involvement of specific microRNAs and their potential use in clinical practice will be summarized. More specifically, within the subchapter "miRNAs in carotid atherosclerosis", general information about miRNA involvement in atherosclerosis will be described (miR-126, miR-17-92, miR-155 and others) with special emphasis put on miRNAs affecting carotid plaque progression and stability (e.g. miR-145, miR-146 or miR-217). In the subchapter "miRNAs in acute stroke", we will provide insight into recent knowledge from animal and human studies concerning miRNA profiling in acute stroke and their expression dynamics in brain tissue and extracellular fluids (roles of, e.g. let-7 family, miR-21, miR-29 family, miR-124, miR-145, miR-181 family, miR-210 and miR-223). Subchapters dealing with "miRNAs and AV malformations" and "miRNAs and intracranial aneurysms" will focus on miR-21, miR-26, miR-29 family and miR-143/145.