Cardiac Imaging After Ischemic Stroke or Transient Ischemic Attack

Clinical applications of artificial intelligence and machine learning in neurocardiology: a comprehensive review

Neurocardiology is an evolving field focusing on the interplay between the nervous system and cardiovascular system that can be used to describe and understand many pathologies. Acute ischemic stroke can be understood through this framework of an interconnected, reciprocal relationship such that ischemic stroke occurs secondary to cardiac pathology (the Heart-Brain axis), and cardiac injury secondary to various neurological disease processes (the Brain-Heart axis). The timely assessment, diagnosis, and subsequent management of cerebrovascular and cardiac diseases is an essential part of bettering patient outcomes and the progression of medicine. Artificial intelligence (AI) and machine learning (ML) are robust areas of research that can aid diagnostic accuracy and clinical decision making to better understand and manage the disease of neurocardiology. In this review, we identify some of the widely utilized and upcoming AI/ML algorithms for some of the most common cardiac sources of stroke, strokes of undetermined etiology, and cardiac disease secondary to stroke. We found numerous highly accurate and efficient AI/ML products that, when integrated, provided improved efficacy for disease prediction, identification, prognosis, and management within the sphere of stroke and neurocardiology. In the focus of cryptogenic strokes, there is promising research elucidating likely underlying cardiac causes and thus, improved treatment options and secondary stroke prevention. While many algorithms still require a larger knowledge base or manual algorithmic training, AI/ML in neurocardiology has the potential to provide more comprehensive healthcare treatment, increase access to equitable healthcare, and improve patient outcomes. Our review shows an evident interest and exciting new frontier for neurocardiology with artificial intelligence and machine learning.

Cardiac Computed Tomography Detected the Hidden Culprit of a Cryptogenic Stroke: A "Cold" Case

Around 25%-40% of ischemic strokes are cryptogenic, with no identifiable cause despite thorough evaluation. The mechanisms behind cryptogenic strokes are often embolic, frequently originating from occult cardiac sources. An unroofed coronary sinus (UCS), a rare congenital anomaly, involves a partial or complete absence of the coronary sinus roof, leading to a connection between the left atrium and the coronary sinus. This defect can be asymptomatic or present with symptoms such as paradoxical embolism due to shunting. We present the case of a 70-year-old male with prolonged chest pain and a history of neurological symptoms, who was later diagnosed with a UCS (types III and IV) through cardiac computed tomography (CCT). A cardiac bubble test confirmed a right-to-left shunt, which was not detected on transthoracic echocardiography. This case underscores the importance of considering advanced imaging techniques such as CCT in the diagnosis of cryptogenic stroke, as echocardiography may miss defects due to poor visualization of posterior cardiac structures.

Advances in Cardiac Workup for Transient Ischemic Attack: Improving Diagnostic Yield and Reducing Recurrent Stroke Risk

Transient ischemic attack (TIA) is a warning sign for an impending stroke, with a 10-20% chance of a stroke occurring within 90 days of the initial event. Current clinical practice for cardiac workup in TIA includes cardiac enzymes, with 12-lead electrocardiogram, transthoracic echocardiography, and 24-hour Holter monitoring. However, the diagnostic yield of these investigations is variable, and there is a need for better diagnostic approaches to increase the detection of cardiac abnormalities in a cost-effective way. This review article examines the latest research on emerging diagnostic tools and strategies and discusses the potential benefits and challenges of using these advanced diagnostic approaches in clinical practice. Novel biomarkers, imaging techniques, and prolonged rhythm monitoring devices have shown great promise in enhancing the diagnostic yield of cardiac workup in TIA patients. Echocardiography, Transcranial Doppler ultrasound, cardiac MRI, and cardiac CT are among the promising diagnostic tools being studied. We conclude the article with a suggested diagnostic algorithm for cardiac workup in TIA. Further research is necessary to enhance their usefulness and to outline future directions for research and clinical practice in this field.

Animal Models of Ischemic Stroke with Different Forms of Middle Cerebral Artery Occlusion

Ischemic stroke is a common type of stroke that significantly affects human well-being and quality of life. In order to further characterize the pathophysiology of ischemic stroke and develop new treatment strategies, ischemic stroke models with controllable and consistent response to potential clinical treatments are urgently needed. The middle cerebral artery occlusion (MCAO) model is currently the most widely used animal model of ischemic stroke. This review discusses various methods for constructing the MCAO model and compares their advantages and disadvantages in order to provide better approaches for studying ischemic stroke.

Cerebral infarction and in-hospital mortality for patients admitted to hospital with intracardiac thrombus: insights from the National Inpatient Sample

The factors associated with cerebral infarction and mortality in patients hospitalized with intracardiac thrombus are unknown. A retrospective cohort study was undertaken of nationally representative hospital admissions in the National Inpatient Sample with a diagnosis of intracardiac thrombus between 2016 to 2019. Multiple logistic regressions were used to define factors associated with cerebral infarction and in-hospital mortality. There were a total of 175,370 admissions for patients with intracardiac thrombus and 10.1% patients had cerebral infarction (n = 17,675). Intracardiac thrombus represented 4.4% of primary diagnosis for admissions while circulatory conditions (65.4%), infection (5.9%), gastrointestinal conditions (4.4%), respiratory conditions (4.4%) and cancer (2.2%) were the other prevalent primary diagnoses. All-cause mortality was higher for patients with cerebral infarction (8.5% vs 4.8%). The five factors most associated with cerebral infarction were nephrotic syndrome (OR 2.67 95%CI 1.05-6.78), other thrombophilia (OR 2.12 95%CI 1.52-2.95), primary thrombophilia (OR 1.99 95%CI 1.52-2.53), previous stroke (OR 1.61 95%CI 1.47-1.75) and hypertension (OR 1.41 95%CI 1.27-1.56). The strongest independent predictors of death were heparin induced thrombocytopenia (OR 2.45 95%CI 150-4.00), acute venous thromboembolism (OR 2.03 95%CI 1.78-2.33, p < 0.001) acute myocardial infarction (OR 1.95 95%CI 1.72-2.22), arterial thrombosis (OR 1.75 95%CI 1.39-2.20) and cancer (OR 1.57 95%CI 1.36-1.81). Patients with intracardiac thrombus are at risk of cerebral infarction and in-hospital mortality. Nephrotic syndrome, thrombophilia, previous stroke, hypertension, and heparin induced thrombocytopenia were associated with cerebral infarction, while acute venous thromboembolism, acute myocardial infarction, and cancer were predictors of mortality.

Cardiac CT for intra-cardiac thrombus detection in embolic stroke of undetermined source (ESUS)

Introduction

Embolic stroke of undetermined source (ESUS) is a common medical challenge regarding secondary prevention strategy. Cardiac imaging is the cornerstone of embolic stroke workup, in an effort to diagnose high risk cardio-embolic sources. Cardiac computed tomography angiography (CCTA) is an emerging imaging modality with high diagnostic performance for intra-cardiac thrombus detection. The yield of CCTA implementation in addition to standard care in ESUS workup is unknown. Thus, the aim of this study was to assess the utility of CCTA in detecting intra-cardiac thrombi in the routine ESUS workup.

Patients and methods

This is a retrospective observational analysis of ESUS cases managed in vascular neurology unit between 2019 and 2021. Within this ESUS registry, consecutive patients undergoing CCTA were included and carefully analyzed.

Results

During the study period 1066 Ischemic stroke (IS) cases were treated and evaluated. 266/1066 (25%) met ESUS criteria and 129/266 (48%) underwent CCTA. Intra-cardiac thrombus was detected by CCTA in 22/129 (17%; 95% CI, 11.5%-23.5%) patients: left ventricular thrombus (LVT) in 13 (10.1%) patients, left atrial appendage (LAA) thrombus in 8 (6.2%) patients, and left atrial (LA) thrombus in 1 (0.8%) patient. Only 5/22 (23%) of these thrombi were suspected, but could not be confirmed, in trans-thoracic echocardiogram (TTE). Among CCTA-undergoing patients, 27/129 (21%; 95% CI, 14%-28%) were found to have an indication (including pulmonary embolism) for commencing anticoagulation (AC) treatment, rather than anti-platelets. In favor of CCTA implementation, 22/266 (8.2%; 95% CI, 4.9%-11.5%) patients within the entire ESUS cohort were diagnosed with intra-cardiac thrombus, otherwise missed.

Conclusion

CCTA improves the detection of intra-cardiac thrombi in addition to standard care in ESUS patients. The implementation of CCTA in routine ESUS workup can change secondary prevention strategy in a considerable proportion of patients.

Intelligent Algorithm-Based MRI Image Features for Evaluating the Effect of Nursing on Recovery of the Neurological Function of Patients with Acute Stroke

The aim of this study is to analyze the application of early rehabilitation nursing in nursing intervention of neurological impairment among patients with acute ischemic stroke. 116 patients with acute ischemic stroke were selected as the research subjects in this paper. The patients were divided into 58 experimental (early rehabilitation care) and 58 control (routine rehabilitation care) groups according to the difference of care protocols, all of which were performed magnetic resonance imaging on. An image resolution reconstruction algorithm on the basis of deep convolutional neural network is proposed for MRI image processing. The results show that peak signal to noise ratio (PSNR) and structural similarity index measure (SSIM) of the included algorithm were remarkably greater than those of compressed sensing (CS) algorithm and nonlocal similarity and block low rank prior-based NSBL algorithm. Running time was shorter than that of the latter two algorithms (P < 0.05). The neurological impairment scores of patients in the experimental group 3 and 5 weeks after treatment were obviously lower than those of patients in the control group (P < 0.05). The Barthel indexes of patients in the experimental group 3 and 5 weeks after treatment were obviously higher than those of patients in the control group (P < 0.05). FugI-Meyer assessment (FMA) and Disability of Arm-Shoulder-Hand (DASH) scores of patients in the experimental group 3 and 5 weeks after treatment were obviously lower than those of patients in control group (P < 0.05). The results show that the deep learning algorithm for MRI image processing performance is better than the traditional algorithm. It not only improves the image quality but also improves the processing efficiency. Early rehabilitation nursing and routine rehabilitation nursing can effectively improve the neurological deficit symptoms, limb motor function, and daily living ability of patients with acute ischemic stroke, and the effect of early rehabilitation nursing is the best.

Effect of Cerebral Ischemic Strokes in Different Cerebral Artery Regions on Left Ventricular Function

Objectives

The relationship between cerebral ischemic stroke and left ventricular function evaluated by echocardiography has been emphasized. Whether lesions in different cerebral artery regions would result in left ventricular dysfunction remains uncertain.

Methods

Patients were divided into middle cerebral artery (MCA) (n = 79), posterior cerebral artery (PCA) (n = 64), basilar artery (BA) regions (n = 66), and no-ischemic stroke group (n = 209). We retrospectively collected demographic characteristics, hematologic parameters, and ECG results, and a comparison of echocardiographic parameters was performed to determine the relationship between ischemic stroke and left ventricular function.

Results

A total of 418 patients were included. Demographic characteristics did not significantly differ between the ischemic stroke and non-ischemic stroke groups, except for a history of drinking (p &lt; 0.001). Homocysteine levels in the MCA group were higher than those in the PCA and BA groups (p &lt; 0.05). The highly sensitive C-reactive protein (hs-CRP) level was higher in the ischemic stroke group than in the non-ischemic stroke one (p = 0.001). A higher incidence of ST-T changes in the ECG and lower levels of potassium and magnesium in the ischemic stroke group were found. Significant differences in diastolic function between groups were noted, and the early mitral inflow velocity, annular early diastolic velocity, and ratio between the mitral annular early diastolic velocity and mitral annulus atrial inflow velocity in the MCA group were lower than those in the BA group (p &lt; 0.05).

Conclusions

Ischemic strokes exhibited a negative effect on left ventricular diastolic function by echocardiography, especially in MCA region infarcts. These results are of great importance for neurologists as they highlight the need for left ventricular function evaluation after stroke to regulate therapy strategies in time.

Effects and Mechanisms of Bone Marrow Mesenchymal Stem Cell Transplantation for Treatment of Ischemic Stroke in Hypertensive Rats

Background and Objectives

Stroke is the most common cause of human death and functional disability, resulting in more than 5 million deaths worldwide each year. Bone marrow mesenchymal stem cells (BMSCs) are a kind of stem cell that are able to self-renew and differentiate into many types of tissues. Therefore, BMSCs have the potential to replace damaged neurons and promote the reconstruction of nerve conduction pathways and connective tissue. However, it remains unknown whether transplanted BMSCs promote angiogenesis or improve the tissue microenvironment directly or indirectly through paracrine interactions. This study aimed to determine the therapeutic effect of BMSCs on ischemic stroke with hypertension in a rodent model and to explore the possible mechanisms underlying any benefits.

Methods and Results

Middle cerebral artery occlusion was used to establish the experimental stroke model. The area of cerebral infarction, expression of vascular endothelial growth factor (VEGF) and glial cell line-derived neurotrophic factor (GDNF), and increment of astrocyte were measured by TTC staining, western blot, real-time quantitative polymerase chain reaction (RT-qPCR) and immunocytochemistry. The results showed a smaller area of cerebral infarction and improved neurological function scores in animals treated with BMSCs compared to controls. The results of RT-qPCR and western blot assays showed higher expression of VEGF and GDNF in BMSC-treated animals compared with controls. Our study also showed that one round of BMSCs transplantation significantly promoted the proliferation of subventricular zone and cortical cells, especially astrocytes, on the ischemic side following cerebral ischemia.

Conclusions

Above findings support that BMSCs have therapeutic effects for ischemic stroke complicated with hypertension, which may occur via up-regulated expression of VEGF and GDNF and reduction of neuronal apoptosis, thereby promoting the recovery of nerve function.

MiR-429 Inhibits the Angiogenesis of Human Brain Microvascular Endothelial Cells through SNAI2-Mediated GSK-3β/β-Catenin Pathway

MicroRNA (miRNA) dysfunction has been confirmed as a key event of ischemic stroke appearance. This study is aimed at revealing the role of miR-429 in the angiogenesis of HBMECs. The HBMECs were treated with oxygen and glucose deprivation (OGD) to establish the ischemic cell model. The qRT-PCR was used to measure the expression levels of the miR-429 in the serums of the patients or cells, and CCK-8, wound healing assay, and tube formation assay were used to observe the effects of miR-429 on the phenotype of HBMECs. Moreover, the Targetscan, dual-luciferase reporter assay, and Western blot were used to reveal the downstream target and regulation mechanism of miR-429 in OGD-induced HBMECs. The results showed that miR-429 was significantly upregulated in the serums of the patients, and overexpressed miR-429 could extremely inhibit the viability, migration, and tube formation of OGD-induced HBMECs. Furthermore, it was found that SNAI2 was a downstream factor of miR-429, and SNAI2 could rescue the effects of miR-429 on OGD-induced HBMECs. Besides, the Western blot showed that miR-429 could affect the activity of GSK-3β/β-catenin pathway via inhibiting the expression of SNAI2. In conclusion, this study suggests that miR-429 inhibits the angiogenesis of HBMECs through SNAI2-mediated GSK-3β/β-catenin pathway.

Cardiac imaging in ischemic stroke or transient ischemic attack of undetermined cause: Systematic review & meta-analysis

BACKGROUND

Patients with ischemic stroke or transient ischemic attack (TIA) of undetermined cause often undergo cardiac imaging in search of a cardioembolic source. As the choice of the most appropriate imaging approach is controversial and therapeutic implications have changed over time, we aimed to identify in patients with "cryptogenic stroke or TIA" the yield of transthoracic or transesophageal echocardiography (TTE or TEE) and cardiac computed tomography (CT).

METHODS AND RESULTS

We performed a systematic review and meta-analysis according to the PRISMA guidelines. Included were studies that assessed consecutive patients with ischemic stroke or TIA of undetermined cause to evaluate the yield of TTE, TEE, or cardiac CT for detecting cardioembolic sources. For each type of cardioembolic source the pooled prevalence was calculated. Only six out of 1458 studies fulfilled the inclusion criteria (1022 patients). One study reported the yield of TTE, four of TEE, and one of both TTE and TEE; no study assessed cardiac CT. Mean patient age ranged from 44.3-71.2 years, 49.2-59.7% were male. TTE detected 43 cardioembolic sources in 316 patients (4 (1.3%) major, 39 (12.3%) minor), and TEE 248 in 937 patients (55 (5.9%) major, 193 (20.6%) minor). The most prevalent major cardioembolic source was left atrial appendage thrombus, yet results were heterogeneous among studies.

CONCLUSIONS

TTE and TEE infrequently detect major cardioembolic sources that require a change of therapy. Findings should be interpreted with caution due to the limited number of studies. A large-sized prospective clinical trial is warranted to support evidence-based decision-making.

[Cardiac diagnostics after ischemic stroke or transitory ischemic attack]

Stroke is the most common cause of permanent disability and one of the most common causes of death. Cardio-embolic strokes are associated with a poor prognosis and a high risk of recurrence compared to other stroke etiologies. The most common source of cardiac embolism is atrial fibrillation which must be quickly identified to optimize secondary stroke prevention. A structured evaluation after ischemic stroke includes taking the medical history, a physical examination, 12-lead ECG recording, rhythm monitoring for 72 h, transthoracic echocardiography and transesophageal echocardiography, if an atrial embolic source of stroke is suspected. Extended cardiac work-up (e. g., MRI/CT, prolonged rhythm monitoring) should be performed in selected patients based on diagnostic findings.

Cardiovascular thrombotic complications in acute ischemic stroke assessed by chest spectral computed tomography during COVID-19

During the pandemic context, diagnostic algorithms had to be adapted considering the decimated medical personnel, local technical resources, and the likelihood of contamination. Given the higher probability of thrombotic complications related to COVID-19 and the availability of a dual-layer spectral computed tomography (CT) scanner, we have recently adopted the use of low-dose, non-gated, chest CT scans performed five minutes after contrast administration among patients admitted with acute ischemic stroke (AIS) undergoing cerebrovascular CT angiography. Dual-layer spectral CT comprises a single X-ray source and two-layer detector with different photon-absorption capabilities. In addition to conventional images, the two distinct energy datasets obtained enable multiparametric spectral analysis without need to change the original scanning protocol. The two spectral features that emerge as most useful for patients with AIS are virtual monoenergetic imaging and iodine-based results. Aside from the evaluation of lung parenchyma, this novel strategy enables ruling out cardioembolic sources and simultaneously providing evidence of pulmonary and myocardial injury in a single session and immediately after CT cerebrovascular angiography. Furthermore, it involves a non-invasive, seemingly accurate, unsophisticated, safer (very low radiation dose and no contrast administration), and cheaper tool for ruling out cardioembolic sources compared to transesophageal echocardiogram and cardiac CT. Accordingly, we sought to standardize the technical aspects and overview the usefulness of delayed-phase, low-dose chest spectral CT in patients admitted with AIS.