Perioperative Antiplatelet Therapy for the Stent-Assisted Coil Embolization: Results of the Questionnaire Survey.

Objective: This study aimed to determine the status of perioperative antiplatelet therapy in stent-assisted coil embolization (SAC) in Japan. Methods: The questionnaire consisted of 13 questions and used Google forms, and was sent to institutions where endovascular specialists were employed. The results were analyzed. Results: The responses from 307 centers indicated that the timing of initiation of antiplatelet therapy was 14 days-1 month before treatment in half of centers, and 7-14 days before treatment in the other half. Platelet function tests were performed at 165 centers (56.2%), of which 136 centers (46.3%) performed these tests for all patients, with the VerifyNow system being the most widely used tool. The duration of postoperative dual antiplatelet therapy was 6, 3, and 12 months in 169 (57.7%), 70 (23.5%), and 42 (14.3%) centers, respectively. The antiplatelet agents used for monotherapy were P2Y12 receptor antagonists or aspirin, with a postoperative period of up to 12 months in 139 centers (47.3%), 24 months in 68 centers (23.1%), and longer than 24 months in 50 centers (17%). Conclusion: Current antiplatelet therapy for SAC in Japan varies widely among institutions. Moreover, each center has its own empirical rules for SAC. Therefore, the findings of this survey suggest the need to establish guidelines for optimal periprocedural antiplatelet therapy for SAC.

Optimal duration of dual antiplatelet therapy for stent-assisted coiling or flow diverter placement.

BACKGROUND: Dual antiplatelet therapy (DAPT) is necessary to prevent thromboembolic complications after stent-assisted coiling (SAC) or flow-diversion (FD) for cerebral aneurysms, but the optimal antiplatelet regimen remains unclear. OBJECTIVE: To determine the optimal DAPT duration in patients with SAC/FD. METHODS: This multicenter cohort study enrolled patients who received SAC/FD for cerebral aneurysms at seven Japanese institutions between January 2010 and December 2020. The primary outcome was the time from procedure to the occurrence of a composite of target vessel-related thromboembolic events, procedure-unrelated major bleeding events, or death. The cumulative event-free survival rates were analyzed using a Kaplan-Meier curve, and the differences in each outcome between the groups dichotomized by the duration of DAPT were analyzed using the log-rank test. RESULTS: Of 632 patients (median observational period, 646 days), primary outcome occurred in 63 patients (10.0%), most frequently within 30 days after the procedure. The cumulative event-free survival rates at 30 days, 1 year, and 2 years after the procedure were 93.3% (91.4 to 95.3%), 91.5% (89.3 to 93.7%), and 89.5% (87.0 to 92.0%), respectively. The cumulative event-free survival rates after switching to monotherapy were similar for the >91 and <90 days DAPT groups in the population limited to patients who were switched from DAPT to monotherapy without major clinical events. CONCLUSIONS: Thromboembolic events rarely occurred beyond 30 days after SAC/FD. The duration of DAPT may be shortened if patients have a periprocedural period without events. Further prospective studies are warranted to determine the optimal duration of antiplatelet therapy. TRIAL REGISTRATION NUMBER: UMIN000044122 :https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000050384.

Protective effects of alpha-mangostin encapsulated in cyclodextrin-nanoparticle on cerebral ischemia.

The production of reactive oxygen species (ROS) during and after the onset of an ischemic stroke induces neuronal cell death and severely damages brain function. Therefore, reducing ROS by administrating antioxidant compounds is a promising approach to improving ischemic symptoms. Alpha-mangostin (α-M) is an antioxidant compound extracted from the pericarp of the mangosteen fruit. Reportedly, α-M decreases neuronal toxicity in primary rat cerebral cortical neurons. In this study, we investigated the neuroprotective activity of α-M in both in vitro and in vivo assays. Pretreatment with α-M inhibited excessive cellular ROS production after oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro using an SH-SY5Y (human neuroblastoma) cell line. In addition, α-M maintained mitochondrial membrane potential and suppressed mitochondrial-specific ROS production induced by OGD/R. Meanwhile, the low bioavailability of α-M due to its poor water solubility has been an insuperable obstruction impeding extensive investigations of the biological functions of α-M and its medical applications. To overcome this problem, we synthesized a cyclodextrin-based nanoparticle (CDNP) that is known to increase the loading efficiency and binding constant of α-M, compared with cyclodextrins themselves. This nano-formulated α-M (α-M/CDNP) was optimized for an in vivo ischemic stroke model. Our results indicated that α-M/CDNP (25 mg/kg/injection) reduced infarct volume and improved neurological behavior (p = 0.036 and p = 0.046, respectively). These in vivo results suggest that α-M appears to cross the blood-brain barrier (BBB) with the help of a nano-formulation with CDNP. Combining an in vitro BBB model and a physicochemical binding assay between α-M and albumin, it is speculated that α-M released from CDNP would interact with albumin during its prolonged circulation in the blood, and the resultant α-M/albumin complex may cross the BBB through the absorptive-mediated transcytosis pathway. These findings suggest the potential clinical application of α-M in ischemic stroke treatment.

Platelet reactivity after clopidogrel loading in patients with acute ischemic stroke.

Objective: It remains unclear when sufficient antiplatelet effect is achieved after administration of a loading dose of clopidogrel in patients with acute ischemic stroke (AIS). This study aimed to evaluate the clopidogrel response in patients with AIS identified by the platelet function test (PFT). Methods: P2Y12 reaction unit (PRU) values measured using VerifyNow at baseline and at 6, 24, and 72 h after administration of a loading dose (300 mg) of clopidogrel were compared between patients with AIS and those of other cerebrovascular diseases (CVD). The prevalence of clopidogrel abnormal response and its associated factors were examined. Results: The PRU value was significantly reduced with time in the other CVD group (p < 0.0001), and also in the AIS group (p = 0.0073). The PRU values were significantly higher in the AIS group than in the other CVD group (p < 0.0001 between the groups, baseline: 314 ± 53 vs. 284 ± 62, p = 0.35; 6 h: 290 ± 66 vs. 214 ± 71, p = 0.016; 24 h: 270 ± 75 vs. 190 ± 70, p < 0.0001; and 72 h: 231 ± 76 vs. 163 ± 93, p = 0.105). The prevalence of clopidogrel hypo-responder (PRU > 240 at 24 h after administration) was higher in the AIS group (79 vs. 33%, p < 0.0001) and associated with the baseline PRU value but not with the cytochrome P450 2C19 genotype or clinical ischemic events. Conclusions: Residual platelet reactivity at 24 h after clopidogrel loading was substantially higher in patients with AIS than in patients with other CVD. In addition, most patients with AIS were judged to be hypo-responders on PFT. This should be carefully interpreted in patients with AIS because of poor specificity for predicting clinical ischemic events.

The safety and efficacy of periprocedural intravenous anticoagulants for acute ischemic stroke patients who underwent endovascular treatment: Sub-analysis of the RESCUE-Japan Registry 2.

The efficacy and safety of periprocedural anticoagulant therapy are still controversial. We investigated the effects of periprocedural anticoagulation on patients who underwent endovascular therapy (EVT) for acute ischemic stroke (AIS). The patients were dichotomized into two groups according to the use of intravenous anticoagulant during or within 24 h after EVT (AC or non-AC group). Primary outcome was defined as a modified Rankin Scale (mRS) score of 0-2 at 90 days. Safety outcomes were defined as any or symptomatic intracerebral hemorrhages (ICH). Among 1278 enrolled patients, 740 patients (57.9%) were in the AC group and the remaining 538 patients (42.1%) were in the non-AC group. The median dose of heparin was 5000 units intraoperatively, and 10,000 units /day postoperatively. In the AC group, hypercholesterolemia, higher pre-stroke modified Rankin Scale score, non-cardiac embolism etiology, higher rate of anticoagulant premedication, non-administration of t-PA (tissue plasminogen activator), later admission, and longer procedure time were observed. The rate of primary outcomes was not significantly different between the AC and non-AC groups (40.1% vs. 43.9%; adjusted odds ratio, 1.29; 95% CI, 0.96-1.73; p = 0.09). The incidence of any (26.2% vs. 25.7%; p = 0.80; adjusted odds ratio, 0.97; 95% CI, 0.72-1.22) and symptomatic (4.3% vs. 5.0%; p = 0.52; adjusted OR, 0.83; 95% CI, 0.46-1.51) intracranial hemorrhage within 72 h were not significantly different between the groups. Periprocedural anticoagulant therapy after acute revascularization did not relate to prognosis and intracranial hemorrhage after EVT.

The Effect of Stent Design on Plaque Protrusion after Carotid Artery Stenting.

Objective: The association between stent design and post-stent intravascular findings after carotid artery stenting (CAS) was evaluated. Methods: Among the 79 patients who underwent CAS between March 2016 and June 2020 at our institution, we retrospectively analyzed 65 patients with full post-stent intravascular evaluation by both optical frequency domain imaging and angioscopy. All CAS procedures were performed under the flow reversal method, and the stent selection was determined by each operator's discretion, depending on the vessel anatomy or plaque characteristics. The patient's characteristics, plaque characteristics, ischemic complication, and post-stent intravascular findings (plaque protrusion, vessel wall apposition of stent) were compared between the closed-cell and open-cell stent groups. Results: The closed-cell group (n = 34) had more high-risk plaques, such as symptomatic lesions or intraplaque hemorrhages, on MRI compared with the open-cell group (n = 31). There was no difference in the rate of ischemic complications between the groups. Although there was no difference in the frequency of plaque protrusion between the two, the maximum height of the protruded plaque was higher in the open-cell group (320 vs. 612 µm, p = 0.003) and incomplete apposition was higher in the closed-cell group (85.3 vs. 6.5%, p <0.0001). Conclusion: The open-cell stent provided better apposition but had larger plaque protrusion. The need for a new hybrid stent that combines the merits of both open- and closed-cell stents was suggested.

Nafamostat protects against early brain injury after subarachnoid hemorrhage in mice.

This study aimed to evaluate the effects of nafamostat, a serin protease inhibitor, in the management of subarachnoid hemorrhage (SAH). SAH was induced by endovascular perforation in male mice. Nafamostat was administered intraperitoneally four times immediately after SAH induction. Cerebral blood flow, neurological behavior tests, SAH grade and protein expression were evaluated at 24 h after SAH induction. In the in vitro model, human brain microvascular endothelial cells (HBMVECs), HBVECs were exposed to thrombin and hypoxia for 24 h; nafamostat was administered and the protein expression was evaluated. Eighty-eight mice were included in the in vivo study. Fifteen mice (17%) were excluded because of death or procedure failure. Nafamostat exerted no significant effect on the SAH grade or cerebral blood flow; however, it improved the neurological behavior and suppressed the thrombin and MMP-9 expression. In addition, nafamostat suppressed the ICAM-1 expression and p38 phosphorylation in the in vitro study. Nafamostat has a protective effect against HBMVEC after exposure to thrombin and hypoxia, suggesting its role in improving the neurological outcomes after SAH. These findings indicate that nafamostat has the potential to be a novel therapeutic drug in the management of SAH.

Involvement of Cerebral Blood Flow on Neurological and Behavioral Functions after Subarachnoid Hemorrhage in Mice.

OBJECTIVE: Cerebral Blood Flow (CBF) change after Subarachnoid Hemorrhage (SAH) is strongly associated with brain injuries such as early brain injury and delayed cerebral ischemia. We evaluated the correlation between CBF using Laser Speckle Flow Imaging (LSFI) after SAH and neurological findings in the sub-acute phase. METHOD: An SAH was induced by endovascular perforation in male mice. CBF was quantitatively measured by using LSFI at six time points, immediately to 14 days after SAH induction. Behavior tests and survival rate were evaluated. The mice were divided into recovery and hypo-perfusion groups according to their CBF at 1 day after the procedure. RESULT: Forty mice were included in this study. Five mice (20%) were included in the hypo-perfusion group, and the remaining 20 (80%) mice were classified as the recovery group. The decrease of CBF in the recovery group was observed until 1 day after the procedure. However, the decrease of CBF in the hypo-perfusion group was prolonged until 7 days after the procedure. Neurological findings and survival rates in the hypo-perfusion group were significantly worse than those in the recovery group. The low alternation cases (≤ 50%) in the Y-maze test in the recovery group (n = 5) had significantly lower CBF at 1 day after the procedure. CONCLUSION: Low blood flow at 1 day after SAH was associated with worse survival rate, neurological findings, and memory disturbance. Early improvement in CBF may be associated with an improved prognosis after SAH.

Potential therapeutic effects of Nrf2 activators on intracranial hemorrhage.

Intracranial hemorrhage (ICH) is a devastating disease which induces high mortality and poor outcomes including severe neurological dysfunctions. ICH pathology is divided into two types: primary brain injury (PBI) and secondary brain injury (SBI). Although there are numerous preclinical studies documenting neuroprotective agents in experimental ICH models, no effective drugs have been developed for clinical use due to complicated ICH pathology. Oxidative and inflammatory stresses play central roles in the onset and progression of brain injury after ICH, especially SBI. Nrf2 is a crucial transcription factor in the anti-oxidative stress defense system. Under normal conditions, Nrf2 is tightly regulated by the Keap1. Under ICH pathological conditions, such as overproduction of reactive oxygen species (ROS), Nrf2 is translocated into the nucleus where it up-regulates the expression of several anti-oxidative phase II enzymes such as heme oxygenase-1 (HO-1). Recently, many reports have suggested the therapeutic potential of Nrf2 activators (including natural or synthesized compounds) for treating neurodegenerative diseases. Moreover, several Nrf2 activators attenuate ischemic stroke-induced brain injury in several animal models. This review summarizes the efficacy of several Nrf2 activators in ICH animal models. In the future, Nrf2 activators might be approved for the treatment of ICH patients.

Importance of CBF measurement to exclude concomitant cerebral infarction in the murine endovascular perforation SAH model.

OBJECTIVE: Concomitant cerebral infarction (CI) is could be a potential concern in experimental subarachnoid hemorrhage (SAH) induced by endovascular perforation. We propose a noninvasive method for excluding CI in a murine SAH model by using Laser speckle flow imaging (LSFI). METHODS: An SAH was induced with endovascular perforation (EVP) in male ddY mice. The cerebral blood flow (CBF) was quantitatively measured in the bilateral cerebral cortex was performed by using LSFI at five timepoints (preprocedure, immediately after, and 3 hours, 6 hours, and 24 hours after the procedure). The mice were then euthanized, and the SAH grade and volume of the CI were evaluated. The mice were divided into the SAH group and the SAH + CI group. Differences between the groups were assessed. RESULTS: Forty-eight mice were used in this study. Six were the sham control group. Five SAH mice died within 24 hours after the procedure. A large CI on the ipsilateral side occurred in 15 (40.5%) mice (i.e., SAH + CI group). The remaining 22 (59.5%) mice were classified as the SAH group. The SAH grading score was not significantly different between the groups. The neurological score and CBF of the ipsilateral hemisphere were significantly higher in the SAH group than in the SAH + CI group (neurological score: 12.3 vs. 8, p < 0.01; CBF: 343.1 vs. 205.5; p < 0.01). The cut-off modified neurological score for excluding CI was 8 (area under the curve [AUC]: 0.77) and CBF at 24 hours after the procedure was 279.2 (AUC:0.856). CONCLUSIONS: Using LSFI is less invasive and effectively excludes concomitant CI in experimental SAH. This methodological protocol may ad in improving the quality of the EVP-SAH model.

Long-Term Outcome of Endovascular Therapy for Large or Giant Thrombosed Intracranial Aneurysms.

OBJECTIVE: Large or giant thrombosed intracranial aneurysms (LGTIAs) are highly associated with poor prognosis and remain a challenging disease to treat by either surgery or endovascular treatment (EVT). EVT is considered more difficult for complicated aneurysm like LGTIAs. To understand long-term clinical and angiographic outcomes of EVT for LGTIAs, we retrospectively analyzed our single-center data on multimodality EVT for patients with LGTIAs. METHODS: From the data of 35 EVT procedures performed in 31 consecutive patients with LGTIAs at our institution between December 2004 and December 2018, the rate of periprocedural complications, clinical outcomes at 12 months after EVT, and the rate of aneurysm recurrence were analyzed, and their related factors were evaluated. RESULTS: Initial EVTs were performed by deconstructive (n = 10) or reconstructive (n = 21) techniques. Although 5 patients (16%) died during the periprocedural period, 23 (74%) had good outcome at 12 months after the procedures. Among 26 patients with long-term follow-up, aneurysm recurrence was observed in 6 patients (23.1%; median time from treatment, 33.2 months). Aneurysm recurrence was significantly higher in patients with basilar artery aneurysm (P = 0.0421) and stroke (P = 0.0307); however, there was no significant difference between the procedures and devices used. CONCLUSIONS: Multimodality EVT for LGTIAs was performed with similar clinical outcomes and better radiologic outcomes compared with previous reports. New innovative techniques and devices are expected to be helpful for long-term aneurysm occlusion.

Correlation Between the VerifyNow P2Y12 Assay and the Newly Developed APAL System in Neuroendovascular Patients.

OBJECTIVE: Light transmission aggregometry (LTA) is the gold standard method for assessing platelet function. Recently, a new parameter called adenosine diphosphate (ADP)-induced platelet aggregation level (APAL) was developed to aid interpretation of LTA results. APAL is a score calculated based on platelet aggregation patterns upon exposure to 1 µM and 10 µM ADP and is determined using an automated coagulation analyzer. We compared APAL and VerifyNow P2Y12 assay for neuroendovascular patients. METHODS: 42 patients who have received antiplatelet therapy were studied. Platelet function tests were performed on CS-2400 for APAL and VerifyNow P2Y12 assay was used for P2Y12 reaction unit (PRU) and % inhibition. RESULTS: Moderate correlations were observed between APAL and PRU (r=0.64, p<0.001) and between APAL and % inhibition (r=-0.74, p<0.001). The optimal threshold for APAL was 8.2 for PRU (threshold=240) and 8.1 for % inhibition (threshold=26%). The percentage of agreement between the above thresholds was 90.9% between PRU and APAL and 77.3% between % inhibition and APAL. CONCLUSIONS: The APAL system exhibits moderate correlation with PRU and % inhibition. APAL testing is a good choice for a clinical laboratory already in possession of Sysmex CS series analyzers. In this setting, APAL testing can significantly decrease the cost of platelet function testing for patients on antiplatelet therapy.

The Mitochondria-targeted Peptide, Bendavia, Attenuated Ischemia/Reperfusion-induced Stroke Damage.

After ischemic stroke, oxygen and nutrition depletion induce mitochondrial dysfunction, which aggravates brain injury. Bendavia, a mitochondria-targeted tetra-peptide, has anti-oxidative and anti-inflammatory activities. We previously reported that bendavia protected human brain microvascular endothelial cells against oxygen/glucose deprivation (OGD)-induced damage via preserving mitochondrial function. The effects of bendavia on mitochondrial function include the inhibition of reactive oxygen species (ROS) production, inhibition of apoptosis, and restoration of adenosine tri-phosphate synthesis. However, the influence of bendavia on the blood-brain barrier (BBB) and neurons after brain ischemia/reperfusion damage is unclear. The aim of this study was to investigate whether bendavia has protective effects against ischemia/reperfusion damage using both in vivo and in vitro models. The in vivo experiments were conducted in mice, which were subjected to transient middle cerebral occlusion (t-MCAO) to induce brain ischemia/reperfusion damage. After t-MCAO, the cerebral blood flow (CBF), neurological deficits, infarct volume, BBB permeability, and microglia/macrophage activation were assessed. Compared to the vehicle group, bendavia administration (administered twice; immediately after reperfusion and 4 h later) attenuated the sensori-motor dysfunction and infarct formation independent of CBF variation. In addition, bendavia decreased BBB hyper-permeability and microglia/macrophage activation. The in vitro experiments were conducted utilizing two models: (1) OGD/re-oxygenation (OGD/R) or (2) hydrogen peroxide (H2O2)-induced neuron damage. In both models, bendavia inhibited neuronal cell death induced by OGD/R or H2O2. These findings indicated that bendavia attenuated brain ischemia/reperfusion damage and has direct neuroprotective effects against cell injury. Therefore, bendavia may be a novel therapeutic agent to improve ischemic stroke patient outcome.

Case of Iatrogenic Vertebro-Vertebral Arteriovenous Fistula Treated by Combination of Double-Catheter and Balloon Anchoring Techniques.

BACKGROUND: A case of high-flow cervical vertebro-vertebral arteriovenous fistula (VVAVF), which was occluded with detachable coils by the transarterial/transvenous double-catheter technique and balloon anchoring technique, is reported. CASE DESCRIPTION: A 32-year-old male who had a history of dilated cardiomyopathy, heart failure, and arrhythmia under anticoagulation presented with a neck bruit after a right internal jugular vein puncture. A high-flow VVAVF between the right vertebral artery (VA) and vertebral vein (VV) was revealed by ultrasonography and angiography. To extirpate the shunt while preserving the right VA without using a stent to avoid antiplatelet therapy, the double-catheter technique was used to occlude the vein and shunt tightly, 1 catheter from the venous side and the other from the VA to the VV through the shunt. Finally, stabilization of the coil cage in the dilating VV was secured by placing a balloon distally as an anchor and successfully occluding the shunt with small amounts of coils only on the venous side. The shunt and cervical bruit disappeared immediately after the treatment, and no recurrence was observed. CONCLUSIONS: The double-catheter technique and balloon anchoring technique used in this case seem effective for transvenous embolization of VVAVF when preservation of the VA is desired.

Selective Shunt Occlusion of Direct Carotid-Cavernous Fistula with Vascular Ehlers-Danlos Syndrome by Multidevice Technique: A Case Report and Technical Note.

BACKGROUND: Vascular Ehlers-Danlos syndrome (vEDS) is a vascular disease associated with a genetic collagen abnormality. It is characterized by vessel fragility, vessel rupture, and massive hemorrhage. Carotid-cavernous fistula (CCF) is the most frequent neurovascular complication of vEDS. However, CCF treatment using conventional diagnostic angiography and neuroendovascular therapy can result in a high rate of major complications. CASE DESCRIPTION: We report a case of a right CCF in a 48-year-old man with vEDS. The carotid artery and jugular vein were exposed by direct neck dissection. To avoid systemic vascular complications, multiple catheters were inserted into the shunt segment via the carotid artery and jugular vein. This transarterial and transvenous multidevice technique enabled compact placement of coils in the shunt segment. The CCF was eliminated via selective shunt occlusion. Postoperative magnetic resonance imaging revealed occlusion of the right CCF. CONCLUSIONS: Selective shunt occlusion via a transarterial and transvenous multidevice technique is a useful and safe approach for treating vEDS-associated CCF.

Delayed Stenosis in the Intracranial Vessels following Endovascular Treatment for Acute Stroke.

PURPOSE: To evaluate delayed stenosis of the vessels after endovascular thrombectomy using magnetic resonance (MR) angiography. MATERIALS AND METHODS: Of 82 consecutive patients who underwent successful endovascular treatment for acute intracranial large vessel occlusion between October 2010 and October 2014 at a single institution, 57 patients for whom 3-month radiologic follow-up examinations using MR angiography were available were included in the analysis. MR angiography images were assessed to detect delayed stenosis, which was defined as a decrease in the diameter of treated vessels > 50% compared with MR angiography images obtained 24 hours after endovascular treatment. RESULTS: MR angiography images obtained 3 months after endovascular treatment revealed delayed stenosis of treated vessels in five (8.8%) of 57 patients. All cases of delayed stenosis were asymptomatic and occurred in the middle cerebral artery (MCA). Further serial radiologic follow-up showed gradual improvement of all delayed stenosis over 12 months. CONCLUSIONS: Endovascular treatment poses a risk of delayed stenosis of treated vessels, especially in the MCA. MR angiography is a useful modality in long-term follow-up to evaluate delayed stenosis after endovascular treatment.