The Mechanism of and Preventive Therapy for Stroke in Patients with Atrial Fibrillation

Development and Validation of a Dynamic Nomogram for Predicting 3-Month Mortality in Acute Ischemic Stroke Patients with Atrial Fibrillation

Background

Acute ischemic stroke (AIS) in patients with atrial fibrillation (AF) carries a substantial risk of mortality, emphasizing the need for effective risk assessment and timely interventions. This study aimed to develop and validate a practical dynamic nomogram for predicting 3-month mortality in AIS patients with AF.

Methods

AIS patients with AF were enrolled and randomly divided into training and validation cohorts. The nomogram was developed based on independent risk factors identified by multivariate logistic regression analysis. The prediction performance of the nomogram was evaluated using the area under the receiver operating characteristic curve (AUC-ROC), calibration plots, decision curve analysis (DCA), and Kaplan-Meier survival analysis.

Results

A total of 412 patients with AIS and AF entered final analysis, 288 patients in the training cohort and 124 patients in the validation cohort. The nomogram was developed using age, baseline National Institutes of Health Stroke Scale score, early introduction of novel oral anticoagulants, and pneumonia as independent risk factors. The nomogram exhibited good discrimination both in the training cohort (AUC, 0.851; 95% CI, 0.802-0.899) and the validation cohort (AUC, 0.811; 95% CI, 0.706-0.916). The calibration plots, DCA and Kaplan-Meier survival analysis demonstrated that the nomogram was well calibrated and clinically useful, effectively distinguishing the 3-month survival status of patients with AIS and AF, respectively. The dynamic nomogram can be obtained at the website: https://yanxiaodi.shinyapps.io/3-monthmortality/.

Conclusion

The dynamic nomogram represents the first predictive model for 3-month mortality and may contribute to managing the mortality risk of patients with AIS and AF.

Efficacy and Safety of Anticoagulant Therapy Versus Antiplatelet Therapy in Acute Ischemic Stroke Patients with Atrial Fibrillation

The efficacy and safety of anticoagulant therapy in patients with acute ischemic stroke (AIS) and atrial fibrillation (AF) remain uncertain. This study enrolled 431 AIS and AF patients from Nanjing Drum Tower Hospital between January 2019 and December 2021 and followed for 365 days to determine the associations between anticoagulants and clinical outcomes by assessing modified Rankin Scale (mRS) score, recurrent ischemic stroke/systemic embolism (IS/SE), all-cause mortality, intracranial hemorrhage (ICH) and major bleeding. Final analysis included 400 eligible patients and divided them into antiplatelet group (n  =  191) and anticoagulant group (n  =  209). Anticoagulant therapy was associated with excellent (mRS 0-1; adjusted odds ratio (aOR), 2.63; 95% confidence interval (CI), 1.61-4.30) and favorable functional outcomes (mRS 0-2; aOR, 2.82; 95% CI, 1.69-4.70) and lower risk of all-cause mortality (adjusted hazard ratio (aHR), 0.35; 95% CI, 0.21-0.57), ICH (aHR, 0.45; 95% CI, 0.23-0.87) and major bleeding (aHR, 0.51; 95% CI, 0.28-0.94), without increasing the risk of recurrent IS/SE (aHR, 0.75; 95% CI, 0.45-1.24). In conclusion, anticoagulant therapy may be a more effective and safer option than antiplatelet therapy for AIS patients with AF.

Association Between Atrial Fibrillation and the Risk of Cardiovascular Mortality Among Elderly Adults With Ischemic Stroke in Northeast China: A Community-Based Prospective Study

Background

Elderly people are susceptible to atrial fibrillation (AF) and ischemic stroke (IS); however, less information is known about the association between AF and the risk of cardiovascular disease (CVD) mortality in elderly population with IS. We aimed to investigate the features of AF among aged people with IS and to illustrate whether AF accounted for CVD mortality.

Methods

At baseline, 790 patients with IS were enrolled from the general northeast Chinese elderly population (>60 years) between September 2017 to March 2019. The prevalence, awareness, and treatment of AF in each age group were analyzed, as well as major-related cardiovascular risk factors. The population was followed until July 31, 2021, and information on CVD death was obtained.

Results

A total of 25 people had AF, and the prevalence of AF in the elderly population with IS was 3.2%. The AF prevalence grew along with age from 1% (60–64 years) to 4.3% (70–74 years) and 4.2% (≥75 years), which was higher in the urban residents than in the rural residents (5.7 vs. 2.2%, P = 0.014). The awareness and treatment rates of patients with AF were 80 and 8%. After a median follow-up period of 3.3 years, 58 subjects died due to CVD and 5 subjects were accompanied with AF (rate 70.6/1,000 person-years). Elderly IS patients with AF had a 3.65-fold increased risk of CVD death in the fully adjusted model when compared with non-AF participants.

Conclusion

The AF prevalence increased with age among the elderly population with IS. Moreover, elderly patients with IS in northeast China with AF had a higher CVD mortality. Therefore, early screening and prompt management of AF in elderly population with IS in northeast China are required.

Alphabetical Mnemonic to Assist in the Treatment of an Acute Ischemic Stroke

Determining the treatment plan and how to successfully manage a patient suffering from an acute ischemic stroke can be challenging for a registered nurse (RN) in the emergency department. Using a mnemonic in the treatment process assists in reducing medical errors and increases the likelihood of making positive clinical outcomes. Mnemonics sum up complex strategies into relevant information that can be comprehensible for users. The authors have created a mnemonic strategy to provide RNs in the emergency department with a structured approach to the pharmacotherapeutic strategies used in treating patients with an acute ischemic stroke. All guidelines used throughout the article are in concurrence.

Obstructive sleep apnea and stroke severity: Impact of clinical risk factors

BACKGROUND

Specific clinical and demographic risk factors may be associated with improving or worsening neurologic outcomes within a population of acute ischemic stroke (AIS) patients with a history of obstructive sleep apnea (OSA). The objective of this study was to determine the changes in neurologic outcome during a 14-day recovery as it relates to initial stroke severity in AIS patients with OSA.

METHODS

This retrospective study analyzed baseline clinical risk factors and demographic data collected in a regional stroke center from January 2010 to June 2016. Our primary endpoint measure was the National Institutes of Health Stroke Scale (NIHSS) score and our secondary endpoint measures included the clinical factors associated with improving (NIHSS score ≤7) or worsening (NIHSS score >7) neurological outcome. The relative contribution of each variable to stroke severity and related outcome was determined using a logistic regression. The regression models were checked for the overall correct classification percentage using a Hosmer-Lemeshow test, and the sensitivity of our models was determined by the area under the receiver operating characteristic curve.

RESULTS

A total of 5469 AIS patients were identified. Of this, 96.89% did not present with OSA while 3.11% of AIS patients presented with OSA. Adjusted multivariate analysis demonstrated that in the AIS population with OSA, atrial fibrillation (AF) (odds ratio [OR] = 3.36, 95% confidence interval [CI], 1.289-8.762, P = 0.013) and changes in ambulatory status (OR = 2.813, 95% CI, 1.123-7.041, P = 0.027) showed an association with NIHSS score >7 while being Caucasian (OR = 0.214, 95% CI, 0.06-0.767, P = 0.018) was associated with NIHSS score ≤7.

CONCLUSION

In AIS patients with OSA, AF and changes in ambulatory status were associated with worsening neurological outcome while Caucasian patients were associated with improving neurological outcome. Our findings may have significant implications for patient stratification when determining treatment protocols with respect to neurologic outcomes in AIS patients with OSA.

Danhong Injection Attenuates Cerebral Ischemia-Reperfusion Injury in Rats Through the Suppression of the Neuroinflammation

Neuroinflammation is one of the major causes of damage of the central nervous system (CNS) and plays a vital role in the pathogenesis of cerebral ischemia, which can result in long-term disability and neuronal death. Danhong injection (DHI), a traditional Chinese medicine injection, has been applied to the clinical treatment of cerebral stoke for many years. In this study, we investigated the protective effects of DHI on cerebral ischemia-reperfusion injury (CIRI) in rats and explored its potential anti-neuroinflammatory properties. CIRI in adult male SD rats was induced by middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. Results showed that DHI (0.5, 1, and 2 ml/kg) dose-dependently improved the neurological deficits and alleviated cerebral infarct volume and histopathological damage of the cerebral cortex caused by CIRI. Moreover, DHI (0.5, 1, and 2 ml/kg) inhibited the mRNA expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), intercellular cell adhesion molecule-1 (ICAM-1), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in ischemic brains, downregulated TNF-α, IL-1β, and monocyte chemotactic protein-1 (MCP-1) levels in serum, and reduced the neutrophil infiltration (myeloperoxidase, MPO) in ischemic brains, in a dose-dependent manner. Immunohistochemical staining results also revealed that DHI dose-dependently diminished the protein expressions of ICAM-1 and COX-2, and suppressed the activation of microglia (ionized calcium-binding adapter molecule 1, Iba-1) and astrocyte (glial fibrillary acidic protein, GFAP) in the cerebral cortex. Western blot analysis showed that DHI significantly downregulated the phosphorylation levels of the proteins in nuclear factor κB (NF-κB) and mitogen-activated protein kinas (MAPK) signaling pathways in ischemic brains. These results indicate that DHI exerts anti-neuroinflammatory effects against CIRI, which contribute to the amelioration of CNS damage.

Atrial Fibrillation With and Without Cardiovascular Risk Factors and Stroke Mortality

Aim: The association between atrial fibrillation (AF) and risk of stroke mortality among men and women without traditional cerebrocardiovascular risk factors (TCVRFs) is unclear. This study aimed to determine whether AF was a risk factor for stroke and total cardiovascular disease mortality among individuals without TCVRFs.

Methods: A total of 90,629 Japanese subjects from the Ibaraki Prefectural Health Study aged 40–79 years, with and without TCVRFs, were studied from 1993 to 2013. Hazard ratios (HRs) were calculated using the Cox proportional hazard regression model stratified by sex and the presence of TCVRFs. Covariates were age, systolic blood pressure, anti-hypertensive medication use, and serum total cholesterol levels. A standard 12-lead electrocardiogram at rest was used to screen AF. Cause-specific mortality was classified according to the International Classification of Disease code.

Results: Compared with participants without AF, multivariable-adjusted hazard ratios (with 95% confidence intervals) for stroke mortality among participants without TCVRFs were 4.3 (1.1–17.8) and 15.0 (5.5–40.8) for men and women with AF, respectively. HRs for total cardiovascular disease mortality were 6.2 (2.8–14.2) for men and 10.7 (4.8–24.1) for women. For participants with TCVRFs, multivariable-adjusted HRs for stroke mortality were 3.1 (2.2–4.6) and 4.3 (2.6–7.3), whereas HRs for total cardiovascular disease mortality were 2.9 (2.2–3.8) and 3.5 (2.4–5.1) for men and women, respectively.

Conclusions: AF was found to be an independent risk factor for stroke and total cardiovascular mortality even in individuals without other TCVRFs.

Age-Specific Impact of Atrial Fibrillation on Cardiovascular Mortality Among Japanese Men and Women (The Ibaraki Prefectural Health Study [IPHS])

The age-specific impact of atrial fibrillation (AF) on cardiovascular diseases remains unclear. A total of 90,629 participants who were from 40 to 79 years of age in 1993 were followed up until 2013 as part of the Ibaraki Prefectural Health Study. Hazard ratios for mortality stratified by gender and age groups were calculated using Cox's proportional hazards regression models. A total of 22,794 patients (11,329 men and 11,465 women) died during the follow-up period, including 6,684 patients who died of cardiovascular causes (2,951 men and 3,733 women). On multivariable analysis, participants with AF had an increased risk of cardiovascular-related mortality compared with those without AF. Among participants aged 40 to 64 years, the adjusted hazard ratios were 3.2 (95% confidence interval [CI] 2.0 to 5.3) for men and 7.1 (95% CI 3.2 to 16.0) for women; the corresponding adjusted hazard ratios among participants aged 65 to 79 years were 3.0 (95% CI 2.2 to 4.0) for men and 3.7 (95% CI 2.5 to 5.4) for women. No significant difference in hazard ratios between age groups was found for either gender. AF was significantly associated with all-cause mortality in each age and gender group; again, no significant difference in hazard ratios between the age groups was found in terms of AF. AF may be an independent risk factor for cardiovascular and all-cause mortalities regardless of age.

Anticoagulant Utilization and Direct Oral Anticoagulant Prescribing in Patients with Nonvalvular Atrial Fibrillation

BACKGROUND

Direct oral anticoagulants (DOACs) are indicated for prevention of stroke and embolism in patients with nonvalvular atrial fibrillation (NVAF). These agents have been shown to be non-inferior to warfarin in terms of efficacy and safety. However, their uptake in practice has been variable, and prescribed dosages may be inconsistent with manufacturer recommendations.

OBJECTIVES

To evaluate patterns of oral anticoagulant use in patients with NVAF, including determination of patient characteristics associated with the prescribing of warfarin or DOACs and whether prescribed dosages of DOACs were concordant with manufacturer recommendations.

METHODS

This retrospective chart review was conducted from April to September 2017 at Abbotsford Regional Hospital, Abbotsford, British Columbia. Patients at least 18 years of age with NVAF and CHADS-65 score of 1 or higher were included. Patients with contraindications to oral anticoagulants, those with reversible atrial fibrillation, and those undergoing renal dialysis were excluded. The dosage of DOACs was categorized as too low, too high, or correct in relation to manufacturer recommendations for the Canadian product.

RESULTS

A total of 120 patients were included. At discharge, 83 (69%) of the patients had a prescription for DOAC, 25 (21%) had a prescription for warfarin, and 12 (10%) had no prescription for an oral anticoagulant. There were no statistically significant differences between the warfarin and DOAC groups with respect to patient characteristics. Among the 56 patients for whom a full DOAC dose was indicated, 7 (13%) received a dose that was too low. Among the 23 patients for whom a full DOAC dose was not indicated, 4 (17%) received a dose that was too high.

CONCLUSIONS

At the study hospital, most patients with NVAF and CHADS-65 score of at least 1 had a discharge prescription for DOAC. Patient characteristics appeared to be similar between the warfarin and DOAC groups. For a notable proportion of patients who received a DOAC, the dosage was incorrect. Appropriate prescribing of oral anticoagulants could be further improved by education for prescribers and involvement of hospital pharmacists.

Neuroprotective effect of glycosides in Buyang Huanwu Decoction on pyroptosis following cerebral ischemia-reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Buyang Huanwu Decoction (BYHWD) is used in classical traditional Chinese medicine to prevent and treat cerebral ischemia. Glycosides, which are effective components extracted from BYHWD, mainly include astragaloside IV, paeoniflorin, and amygdalin. These glycosides are the primary pharmacologically effective constituents of BYHWD that act against cerebral ischemic nerve injury; however, the mechanism of action of BYHWD is still unclear.

AIM OF THE STUDY

The present study aimed to determine the effect of BYHWD glycosides on pyroptosis after cerebral ischemia reperfusion injury and explore whether its mechanism involves the classical pyroptosis pathway mediated by NLRP3.

MATERIAL AND METHODS

Adult male Sprague-Dawley rats (n = 140) were randomly divided into seven groups: sham, cerebral ischemia and reperfusion (I/R), glycosides (0.064 g/kg, 0.128 g/kg, and 0.256 g/kg), BYHWD, and AC-YVAD-CMK (caspase-1 inhibitor). A rat model of cerebral I/R was established via classic middle cerebral artery occlusion (MCAO) for 2 h, followed by 24-h reperfusion. Neurological function was estimated using neurological defect scores. Brain infarct volumes were determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining, and nerve cell damage was evaluated by Nissl staining. Pyroptosis was detected using TUNEL and caspase-1 immunofluorescence double staining. Protein expression of NLRP3, ASC, caspase-1, pro-caspase-1, and IL-1β was analyzed using Western blot analysis.

RESULTS

Glycosides improved neurological dysfunction, alleviated neuronal damage, and inhibited neuronal pyroptosis. The 0.128 g/kg glycosides group showed the most significant effects. Furthermore, we observed that this group showed significant inhibition of the expression of NLRP3, ASC, pro-caspase-1, caspase-1, and IL-1β proteins of the NLRP3-mediated classical pathway of pyroptosis.

CONCLUSIONS

Glycosides exert neuroprotective effects by inhibiting pyroptosis of neurons after cerebral I/R injury. The underlying mechanism of action is closely related to the regulation of the classical pyroptosis pathway by NLRP3.

Association between epicardial adipose tissue and embolic stroke after catheter ablation of atrial fibrillation

INTRODUCTION

Risk factors of embolic stroke (ES) after atrial fibrillation (AF) ablation have not been fully elucidated especially among the Asian subjects, particularly regarding epicardial adipose tissue (EAT) in cardiac imaging. We aimed to assess the incidence of ES during a long-term follow-up period after AF ablation and to identify the risk factors associated with postablation ES, specifically focusing on EAT.

METHODS AND RESULTS

We enrolled patients who experienced postablation ES and control subjects from a consortium of AF ablation registries from three institutes in Korea. EAT was assessed using multislice computed tomography before AF ablation. A total of 3464 patients who underwent AF ablation were recruited and followed-up. During a follow-up of 47.2 ± 36.4 months, ES occurred in 47 patients (1.36%) with a CHA₂ DS₂ -VASc score of 1.48 ± 1.39 and the overall annual incidence of ES was 0.34%. Compared with the control group (n = 190), the ES group showed significantly higher prior thromboembolism (TE) and AF recurrence rates, larger left atrium size, lower creatinine clearance rate (CCr), and greater total and peri-atrial EAT volume. Multivariate regression analysis demonstrated larger peri-atrial EAT volume (hazards ratio, 1.065; 95% confidence interval, 1.005-1.128), in addition to a prior history of TE and lower CCr, was independently associated with postablation ES. When a cut-off value of peri-atrial EAT volume of ≥20.15 mL was applied, patients with smaller peri-atrial EAT volume showed significantly higher ES-free survival.

CONCLUSION

Larger peri-atrial EAT volume, in addition to prior TE and lower CCr, was independently associated with postablation ES regardless of AF recurrence and CHA₂ DS₂ -VASc score. (ClinicalTrials.gov number, NCT03479073).

Pattern of stroke in a rural Kenyan hospital

Background

The pattern of stroke in rural population differs from that in urban ones. Although there are many studies on this condition in sub-Saharan Africa, few studies about stroke pattern in a Kenyan rural area exist.. This study therefore aims at describing the characteristics of stroke in a rural Kenyan hospital.

Patients and Methods

The study was conducted on 227 consecutive patients admitted with a World Health Organization (WHO) diagnosis of stroke in Kangundo Hospital, a level IV facility in Machakos, Eastern Kenya, between April 2015 and September 2016. The sub-type and anatomical distribution of stroke as well as the age, gender of the patients were recorded prospectively. Diagnosis was made through physical neurological examination and confirmed by Computerized Tomography (CT) scan imaging. Only those with complete bio-data, past medical and social history, clinical and physical findings of the patients and imaging results were included. The data were entered into a pre-formatted questionnaire, analysed for means, standard deviations and frequencies, and are presented in tables and bar charts.

Results

Out of 3200 medical admissions, 227 (7.09%) had a confirmed diagnosis of stroke. Ischaemic stroke was more common (67.4%) than haemorrhagic stroke (32.6%). It affected mainly the anterior circulation, especially the middle cerebral artery (39%). The mean age of patients was 68.8 years, (Range 32–96). It was more common in females (62%) than in males (38%). Hypertension was the most common (74%) risk factor followed by alcohol abuse (63%), tobacco smoking (48%) and diabetes mellitus (42%).

Conclusion

Ischaemic stroke was the more common major cause of morbidity in the rural hospital studied in Kenya. It occurred most commonly among elderly females, with the most frequent comorbidities being hypertension. In addition, modifiable lifestyle factors like alcohol abuse and cigarette smoking contributed to the prevalence; hence we recommend the control of blood pressure and glucose as well as lifestyle modification to reduce the scourge in our studied population.

Biomarkers Associated with Stroke Risk in Atrial Fibrillation

Background:

Atrial fibrillation (AF) is associated with an increased risk of cardioembolic stroke. The risk of cardioembolism is not adequately reduced with the administration of oral anticoagulants, since a number of patients continue to experience thromboembolic events despite receiving treatment. Therefore, identification of a circulating biomarker to identify these high-risk patients would be clinically beneficial.

Objective:

In the present article, we aim to review the available data regarding use of biomarkers to predict cardioembolic stroke in patients with AF.

Methods:

We performed a thorough search of the literature in order to analyze the biomarkers identified thus far and critically evaluate their clinical significance.

Results:

A number of biomarkers have been proposed to predict cardioembolic stroke in patients with AF. Some of them are already used in the clinical practice, such as d-dimers, troponins and brain natriuretic peptide. Novel biomarkers, such as the inflammatory growth differentiation factor-15, appear to be promising, while the role of micro-RNAs and genetics appear to be useful as well. Even though these biomarkers are associated with an increased risk for thromboembolism, they cannot accurately predict future events. In light of this, the use of a scoring system, that would incorporate both circulating biomarkers and clinical factors, might be more useful.

Conclusions:

Recent research has disclosed several biomarkers as potential predictors of cardioembolic stroke in patients with AF. However, further research is required to establish a multifactorial scoring system that will identify patients at high-risk of thromboembolism, who would benefit from more intensive treatment and monitoring.

Treatment With Intravenous Alteplase for Acute Ischemic Stroke After Reversal of Dabigatran With Idarucizumab: A Case Study

Treatment options for anticoagulated patients presenting with ischemic stroke are limited. Off-label use of idarucizumab to rapidly reverse the anticoagulant effect of dabigatran may ensure eligibility for thrombolytic therapy with alteplase. This case describes a 77-year-old white male who presented to the hospital 89 minutes after sudden onset of right-sided hemiparesis, dysarthria, and facial palsy. Significant history included atrial fibrillation and previous right-sided cortical stroke. Medication reconciliation revealed he was taking dabigatran 150 mg twice a day, with the last dose being 179 minutes before presentation. Neuroimaging revealed no new infarct or hemorrhage, and 60 minutes after arrival, a decision was made to give idarucizumab to reverse the anticoagulant effect of dabigatran. In the absence of any contraindication, he was then treated with intravenous alteplase and idarucizumab. No adverse outcomes were noted, and at discharge, his new stroke symptoms were completely resolved.

Protective effects of tetramethylpyrazine analogue Z-11 on cerebral ischemia reperfusion injury

The aim of our study was to investigate the effects of a new synthetic compound (E) -1- (E) -1- (2- hydroxy -5- chlorophenyl) -3- (3, 5, 6- three methyl pyrazine -2- based) -2- propylene -1 ketone, Z-11, a tetramethylpyrazine analogue, on cerebral ischemia reperfusion injury and the underlying mechanism. 240-260 g adult male Wistar rats were subjected to middle cerebral artery occlusion for 2 h, followed by 22 h of reperfusion. Z-11 (1.7, 3.4 and 6.8 mg/kg, i.p.), Edaravone (3 mg/kg, i.p.) and DMSO (1‰, i.p.) was administered at 2 h after the onset of ischemia. The rats' neurological score, infarct volume, and body weight change were tested, and some oxidative stress markers such as superoxide dismutase (SOD) activity, glutathione (GSH) and malondialdehyde (MDA) contents were evaluated after 22 h of reperfusion. Results showed that neurologic deficit, infarct volume and body weight change were ameliorated after cerebral ischemia reperfusion, and that Z-11 exhibits an excellent effect at a dosage of 6.8 mg/kg. This dose also reduced the content of MDA, and upregulated SOD activity and GSH content. Similarly, 6.8 mg/kg Z-11 treatment inhibited the reactive oxygen species content and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, with the protein levels of Ras-related C3 botulinum toxin substrate1(Rac-1) and mitogenic oxidase (Nox2) downregulated even further. Moreover, the protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream anti-oxidant protein heme oxygenase-1 (HO-1) were upregulated. This indicates that Z-11 could play a protective role in cerebral ischemia-reperfusion injury, and that the protective effect of Z-11 may be related to improvements in the antioxidant capacity of brain tissue. The mechanisms are associated with enhancing oxidant defence systems via the activation of Nrf2/HO-1 and Rac-1/NADPH oxidase pathways.

Platelet function and microparticle levels in atrial fibrillation: Changes during the acute episode

BACKGROUND

Thrombotic risk constitutes a major complication of atrial fibrillation (AF). Platelets and microparticles (MPs) are important for hemostasis and thrombosis, however their participation during AF is not well known. The aim of this study was to characterize platelet function and MPs procoagulant and fibrinolytic activity in AF patients and to determine the effects of an acute-AF episode.

METHODS

Blood was collected from paroxysmal (21) and persistent (16) AF patients referred for AF catheter ablation. Ten patients in sinus rhythm for 10days were induced in AF allowing comparisons of left atrium samples before and after induction. Platelet aggregation with ADP, TRAP, collagen, and ristocetin was studied. Platelet surface expression of PAR-1, αIIbβ3, GPIb and P-selectin were evaluated by flow cytometry, and MPs-associated procoagulant and fibrinolytic activity levels were determined by functional assays.

RESULTS

A specific reduction in platelet aggregation to TRAP, activating the thrombin receptor PAR-1, was found in all AF patients. No differences in platelet receptor expression were found. Yet, after acute-induced AF, the platelet response was improved. Furthermore, a significant decrease of left atrium tissue factor-dependent procoagulant activity of MPs was observed.

CONCLUSION

Acute episodes of AF results in a decrease in MPs-associated tissue factor activity, possibly corresponding to consumption, which in turn favors coagulation and the local production of thrombin. A decreased platelet basal aggregation to TRAP may result from PAR1 desensitization, whereas the improved response after an induced episode of AF suggests activation of coagulation and PAR1 re-sensitization.

Picroside II protects the blood-brain barrier by inhibiting the oxidative signaling pathway in cerebral ischemia-reperfusion injury

BACKGROUND AND PURPOSE

Thrombolysis is used to improve cerebral circulation; at the same time, neuroprotective drugs such as antioxidants should also be used. The aim of these experiments was to explore the protective mechanism of an antioxidant, picroside II, on the blood-brain barrier (BBB) after cerebral ischemia-reperfusion (CI/R) injury.

METHODS

To observe the antagonistic effect of picroside II on CI/R damage, the neurological deficit score and the infarct volume were measured. To detect the protective effect of picroside II on nerve cells and the BBB, the morphology and structure of cortical brain tissue were observed, respectively. To investigate the antioxidant effect and mechanism of picroside II, reactive oxygen species (ROS) content, the activity of Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), and the protein levels of Nox2 and Rac-1 were detected. To investigate the protective mechanism of picroside II on the BBB, the levels of ROCK, MLCK, MMP-2 and claudin-5 were tested.

RESULTS

A higher neurological score, bigger cortex infarction, more damaged neuron structure and injured BBB, increased content of ROS and activity of NADPH oxidase, higher protein levels of Nox2, Rac-1, ROCK, MLCK and MMP-2 and lower levels of claudin-5 were observed in the model group. In the picroside group, the neurological score, neuronal damage, BBB injury, ROS content and NADPH oxidase activity were reduced (P<0.05), and the protein levels of Rac-1, Nox2, ROCK, MLCK and MMP-2 were down-regulated (P<0.05), while the expression of claudin-5 was up-regulated (P<0.05).

CONCLUSIONS

Picroside II could protect the nervous system possibly through reducing the content of ROS by down-regulating the expression of Rac-1 and Nox2 and could protect the BBB through reducing the expression of ROCK, MLCK, and MMP-2, while enhancing the expression of claudin-5.