Background: Although tortuosity of the internal carotid artery (ICA) can pose a significant challenge when performing mechanical thrombectomy, few studies have examined the impact of ICA tortuosity on mechanical thrombectomy outcomes. Methods: In a registry-based hospital cohort, consecutive patients with anterior circulation stroke in whom mechanical thrombectomy was attempted were divided into 2 groups: those with tortuosity in the extracranial or cavernous ICA (tortuous group) and those without (nontortuous group). The extracranial ICA tortuosity was defined as the presence of coiling or kinking. The cavernous ICA tortuosity was defined by the posterior deflection of the posterior genu or the shape resembling Simmons-type catheter. Outcomes included first pass effect (FPE; extended Thrombolysis in Cerebral Infarction score 2c/3 after first pass), favorable outcome (3-month modified Rankin Scale score of 0–2), and intracranial hemorrhage. Results: Of 370 patients, 124 were in the tortuous group (extracranial ICA tortuosity, 35; cavernous ICA tortuosity, 70; tortuosity at both sites, 19). The tortuous group showed a higher proportion of women and atrial fibrillation than the nontortuous group. FPE was less frequently achieved in the tortuous group than the nontortuous group (21% versus 39%; adjusted odds ratio, 0.45 [95% CI, 0.26–0.77]). ICA tortuosity was independently associated with the longer time from puncture to extended Thrombolysis in Cerebral Infarction ≥2b reperfusion (β=23.19 [95% CI, 13.44–32.94]). Favorable outcome was similar between groups (46% versus 48%; P =0.87). Frequencies of any intracranial hemorrhage (54% versus 42%; adjusted odds ratio, 1.61 [95% CI, 1.02–2.53]) and parenchymal hematoma (11% versus 6%; adjusted odds ratio, 2.41 [95% CI, 1.04–5.58]) were higher in the tortuous group. In the tortuous group, the FPE rate was similar in patients who underwent combined stent retriever and contact aspiration thrombectomy and in those who underwent either procedure alone (22% versus 19%; P =0.80). However, in the nontortuous group, the FPE rate was significantly higher in patients who underwent combined stent retriever and contact aspiration (52% versus 35%; P =0.02). Conclusions: ICA tortuosity was independently associated with reduced likelihood of FPE and increased risk of postmechanical thrombectomy intracranial hemorrhage. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02251665.

Background: The “1-3-6-12-day rule” for starting direct oral anticoagulants (DOACs) in patients with nonvalvular atrial fibrillation after acute ischemic stroke or transient ischemic attack recommends timings that may be later than used in clinical practice. We investigated more practical optimal timing of DOAC initiation according to stroke severity. Methods: The combined data of prospective registries in Japan, Stroke Acute Management with Urgent Risk-factor Assessment and Improvement-nonvalvular atrial fibrillation (September 2011 to March 2014) and RELAXED (February 2014 to April 2016) were used. Patients were divided into transient ischemic attack and 3 stroke subgroups by the National Institutes of Health Stroke Scale score: mild (0–7), moderate (8–15), and severe (≥16). The early treatment group was defined as patients starting DOACs earlier than the median initiation day in each subgroup. Outcomes included a composite of recurrent stroke or systemic embolism, ischemic stroke, and severe bleeding within 90 days. Six European prospective registries were used for validation. Results: In the 1797 derivation cohort patients, DOACs were started at median 2 days after transient ischemic attack and 3, 4, and 5 days after mild, moderate, and severe strokes, respectively. Stroke or systemic embolism was less common in Early Group (n=785)—initiating DOACS within 1, 2, 3, and 4 days, respectively—than Late Group (n=1012) (1.9% versus 3.9%; adjusted hazard ratio, 0.50 [95% CI, 0.27–0.89]), as was ischemic stroke (1.7% versus 3.2%, 0.54 [0.27–0.999]). Major bleeding was similarly common in the 2 groups (0.8% versus 1.0%). On validation, both ischemic stroke (2.4% versus 2.2%) and intracranial hemorrhage (0.2% versus 0.6%) were similarly common in Early (n=547) and Late (n=1483) Groups defined using derivation data. Conclusions: In Japanese and European populations, early DOAC initiation within 1, 2, 3, or 4 days according to stroke severity seemed to be feasible to decrease the risk of recurrent stroke or systemic embolism and no increase in major bleeding. These findings support ongoing randomized trials to better establish the optimal timing of DOAC initiation.

Background and Purpose: Cerebral microbleeds (CMB) are associated with stroke and cognitive impairment. We previously reported a high prevalence of CMB in people with Streptococcus mutans expressing Cnm, a collagen-binding protein in the oral cavity. S. mutans is a major pathogen responsible for dental caries. Repeated challenge with S. mutans harboring the cnm gene encoding Cnm induced cerebral bleeding in stroke-prone spontaneously hypertensive rats. The purpose of this longitudinal study is to examine the relationship of cnm -positive S. mutans to the development of CMB. Methods: We retrospectively investigated patients with stroke receiving oral microbiological examination and head 3T magnetic resonance imaging evaluations twice in the period 2014 to 2019, allowing >180-day interval. Patients with cnm -positive S. mutans were compared with those without. Quasi-Poisson regression models were used to explore associations between cnm -positive S. mutans and the increase in number of CMB between the 2 magnetic resonance imaging scans. Results: A total of 111 patients were identified; 21 (19%) with cnm -positive S. mutans and 90 (81%) without. Clinical history, including blood pressure and the use of antithrombotic agents, were comparable between the 2 groups. New CMB were more commonly observed in patients with cnm -positive S. mutans (52% versus 23%; P =0.008). The incidence of CMB was significantly higher in the group with cnm -positive S. mutans , especially in deep areas, (incidence rate ratios [95% CI], 5.1 [1.9–13.6] for CMB in any brain region; 15.0 [5.4–42.0] for deep CMB), which persisted after adjusting for age, sex, hypertension, and renal impairment (4.7 [1.8–11.9] for CMB in any brain region; 13.9 [4.3–44.5] for deep CMB). Conclusions: This study demonstrates that cnm -positive S. mutans is associated with an increased incidence of CMB. Treatment for cnm -positive S. mutans infection may be a novel microbiota-based therapeutic approach for stroke and cognitive impairment.

Early detection of hemorrhagic transformation after reperfusion therapy is crucial in acute stroke treatment. Here, we evaluated the relationship between hemorrhagic transformation and post-reperfusion hyperperfusion using pulsed arterial spin labeling (ASL) perfusion MRI and ¹²³I-iodoamphetamine single-photon emission-computed tomography. Patients who developed hemorrhagic transformation showed significantly higher cerebral blood flow in the affected lesion after thrombolysis and/or endovascular intervention. Focal hyperperfusion (ipsilateral to contralateral ratio >1.5) was associated with hemorrhagic transformation after reperfusion (odds ratio, 9.3; 95% confidence interval, 1.4–64.0). Our findings suggest that post-reperfusion hyperperfusion on ASL could represent a reliable marker of hemorrhagic transformation.

Background We aimed to identify the large ischemic core (LIC) volume ranges in acute ischemic stroke patients that can benefit from mechanical thrombectomy (MT). Methods Consecutive patients within 24 hours of onset of anterior circulation ischemic stroke with large vessel occlusion and ischemic core volumes of 70–300 mL were included from our single-center prospective database from March 2014 to December 2019. Subjects were divided into three groups by baseline ischemic core volume (A: 70–100 mL; B: 101–130 mL; C: >130 mL). We compared modified Rankin Scale (mRS) score 0–2 at 3 months and parenchymal hematoma between patients receiving MT and standard medical treatment (SMT), and determined clinically treatable core volume ranges for MT. Results Of 157 patients (86 women; median age, 81 years; median ischemic core volume, 123 mL), 49 patients underwent MT. In Group A (n=52), MT patients (n=31) showed a higher proportion of mRS 0–2 at 3 months (52% vs 5%, P<0.05) versus SMT, respectively. Group B (n=36) MT patients (n=14) also had a higher proportion of mRS 0–2 at 3 months (29% vs 9%, P=0.13) versus SMT, respectively. In Group C (n=69), only four patients received MT. The 95% confidence intervals for the probability of mRS 0–2 at 3 months in patients with MT (n=49) versus SMT (n=108) intersected at 120–130 mL. Conclusions Ischemic core volumes between 70 and 100 mL may benefit from MT. The treatable upper core limit is approximately 120 mL in selected patients with LIC of 70–300 mL.

Background: Malignant profiles were identified by imaging profiles and unfavorable outcomes that have poor response to reperfusion therapy. Many trials have used this profile in their inclusion criteria including large‐vessel occlusion acute ischemic stroke trials. We aimed to redefine the cutoff values for malignant profile in acute ischemic stroke patients with large‐vessel occlusion regardless of reperfusion therapy. Methods and Results: Consecutive acute ischemic stroke patients with anterior large‐vessel occlusion were prospectively extracted from the National Cerebral and Cardiovascular Center Stroke Registry between March 2014 and December 2017. Diffusion‐Weighted Imaging‐Alberta Stroke Program Early Computed Tomography Score (DWI‐ASPECTS) and diffusion‐weighted imaging lesion ischemic core volume (Vol _DWI ) were measured in acute ischemic stroke patients with large‐vessel occlusion with or without treatment. Unfavorable outcome was defined as a modified Rankin Scale score 5 to 6 at 3 months, and optimal DWI ‐ ASPECTS and Vol _DWI for unfavorable outcome were assessed. In total, 198 patients (111 men, 77±13 years old) were enrolled. Median DWI ‐ ASPECTS was 7 (5‐9), and median Vol _DWI was 55 (6‐134) mL . Among the patients, 72 (36%) patients underwent reperfusion therapy, and 83 (42%) had unfavorable outcomes. The threshold values for a malignant profile on receiver operating characteristic curve analysis for DWI ‐ ASPECTS and Vol _DWI were 4 (area under the curve 0.78, P <0.01; sensitivity 0.71, specificity 0.75) and 71 mL (area under the curve 0.80, P <0.01; sensitivity 0.76, specificity 0.77), respectively. Conclusions: The cutoff values for our redefined malignant profile were DWI ‐ ASPECTS 4 and Vol _DWI 71 mL with no selection bias for reperfusion therapy in the real‐world clinical practice. Clinical Trial Registration: URL : http://www.clinicaltrials.gov Unique identifier: NCT 02251665