Intracranial Hemorrhage Risk in the Era of Antithrombotic Therapies for Ischemic Stroke

Incidence and risk of stroke in Korean patients with congenital heart disease

OBJECTIVES

The incidence and risk of ischemic stroke (IS) and hemorrhagic stroke (HS) in Korean patients with CHD have not been reported, therefore, we aimed to investigate this.

MATERIALS AND METHODS

Participants were selected from the Korean National Health Insurance Service benefit records from 2006-2017. Cases were extracted using diagnosis codes related to CHD. Controls without CHD were selected through age- and sex-matched random sampling at a 1:10 ratio.

RESULTS

The case and control groups included 232,203 and 3,024,633 participants, respectively. The median (interquartile range) follow-up period was 7.28 (3.59-8.73) years. The incidence rates of IS and HS per 100,000 person-years were much higher in cases than in controls (IS: 135 vs. 47; HS: 41.7 vs. 24.9). After adjusting for confounders, CHD was a risk factor for IS and HS (subdistribution HR; 1.96 and 1.71, respectively). In patients with CHD, the following risk factors were identified: diabetes, heart failure, and atrial fibrillation for any stroke; hypertension, atrial septal defects, and use of antiplatelet agents for IS only; and coronary artery bypass graft surgery for HS only.

CONCLUSIONS

Korean patients with CHD have a high risk of stroke. A personalized preventive approach is needed to reduce the incidence of stroke in this population.

Cerebral Hemorrhage: Pathophysiology, Treatment, and Future Directions

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high morbidity and mortality. This review article focuses on the epidemiology, cause, mechanisms of injury, current treatment strategies, and future research directions of ICH. Incidence of hemorrhagic stroke has increased worldwide over the past 40 years, with shifts in the cause over time as hypertension management has improved and anticoagulant use has increased. Preclinical and clinical trials have elucidated the underlying ICH cause and mechanisms of injury from ICH including the complex interaction between edema, inflammation, iron-induced injury, and oxidative stress. Several trials have investigated optimal medical and surgical management of ICH without clear improvement in survival and functional outcomes. Ongoing research into novel approaches for ICH management provide hope for reducing the devastating effect of this disease in the future. Areas of promise in ICH therapy include prognostic biomarkers and primary prevention based on disease pathobiology, ultra-early hemostatic therapy, minimally invasive surgery, and perihematomal protection against inflammatory brain injury.

Machine Learning Analysis of MicroRNA Expression Data Reveals Novel Diagnostic Biomarker for Ischemic Stroke

OBJECTIVES

Ischemic stroke (IS) is one of the leading causes of morbidity and mortality worldwide. Circulating microRNAs have a potential as minimally invasive biomarkers for disease prediction, diagnosis, and prognosis. In this study, we sought to use different machine learning algorithms to identify an optimal model of microRNA by integrating the expression data of pre-selected microRNAs for discriminating patients with IS from controls.

METHODS

The expression level of microRNAs in the peripheral blood of 50 patients with IS and 50 matched controls were assessed through real-time polymerase chain reaction (qRT-PCR). Machine learning algorithms, including artificial neural network, random forest, extreme gradient boosting, and support vector machine (SVM) were employed via R 3.6.3 software to establish diagnostic models for IS.

RESULTS

The IS group had significantly increased expression levels of miR-19a (P < 0.001), miR-148a (P < 0.001), miR-320d (P = 0.003), and miR-342-3p (P < 0.001) compared with the control group. MiR-148a, miR-342-3p, miR-19a, and miR-320d yielded areas under the receiver operating characteristic curve (AUC) of 0.872, 0.844, 0.721, and 0.673, respectively, with 0.740, 0.940, 0.740, and 0.840 sensitivity and 0.920, 0.640, 0.600, and 0.440 specificity, respectively. Model miR-148a + miR-342-3p + miR-19a had the best predictive value when analyzed via SVM algorithm with AUC, sensitivity, and specificity values of 0.958, 0.937, and 0.889, respectively.

CONCLUSION

The diagnostic value of the combination of miR-148a, miR-342-3p, and miR-19a through SVM algorithm has the potential to serve as a feasible approach to promote the diagnosis of IS.

Thrombocytopenia: Effect in Ischemic and Hemorrhagic Stroke

BACKGROUND

There are 2 classification of strokes: ischemic, if caused by an arterial occlusion from a clot or obstruction by atherosclerosis, and hemorrhagic, if caused by the rupture of a vessel and subsequent bleeding. Each type of stroke is influenced by platelet counts and platelet function. The intention of this article is to discuss the role of the platelet in the pathophysiology of acute stroke processes. This serves as a prelude to discussing these processes as disrupted with thrombocytopenia (low platelet counts). Platelets initiate clot formation and obstruct blood flow through the creation of a platelet plug. They also extend the penumbra in ischemic and hemorrhagic strokes. Thrombocytopenia can be a causal factor in an ischemic stroke, a risk factor for hemorrhagic stroke, and a risk factor for hemorrhagic stroke conversion.

METHODS

The aims of this study were to review 1 case study that illustrates the pivotal role of the platelet in strokes and to review the aspect that was impacted by autoimmune thrombocytopenia.

DISCUSSION

Thrombocytopenia is a hematologic disorder not often included in stroke care discussions. Thrombocytopenia sets up strokes to occur and, paradoxically, may also set the patient up for bleeding complications in the brain or groin.

CONCLUSION

Acknowledging the impact of both platelet and thrombocytopenia on stroke causation, stroke interventions, and outcomes is a pivotal aspect of comprehensive stroke care. Platelet function processes are impactful in each point of the continuum of stroke care, prevention, intervention, and discharge.

The role of biomarkers and neuroimaging in ischemic/hemorrhagic risk assessment for cardiovascular/cerebrovascular disease prevention

Stroke prevention in patients with atrial fibrillation is arguably one of the fastest developing areas in preventive medicine. The increasing use of direct oral anticoagulants and nonpharmacologic methods such as left atrial appendage closure for stroke prevention in these patients has increased clinicians' options for optimal care. Platelet antiaggregants are also commonly used in other ischemic cardiovascular and or cerebrovascular conditions. Long term use of oral anticoagulants for atrial fibrillation is associated with elevated risks of major bleeds including especially brain hemorrhages, which are known to have extremely poor outcomes. Neuroimaging and other biomarkers have been validated to stratify brain hemorrhage risk among older adults. A thorough understanding of these biomarkers is essential for selection of appropriate anticoagulant or left atrial appendage closure for stroke prevention in patients with atrial fibrillation. This article will address advances in the stratification of ischemic and hemorrhagic stroke risk among patients with atrial fibrillation and other conditions.

Strictly Lobar Microbleeds Reflect Amyloid Angiopathy Regardless of Cerebral and Cerebellar Compartments

BACKGROUND AND PURPOSE

We aimed to determine whether lobar cerebellar microbleeds or concomitant lobar cerebellar and deep microbleeds, in the presence of lobar cerebral microbleeds, attribute to underlying advanced cerebral amyloid angiopathy pathology or hypertensive arteriopathy.

METHODS

We categorized 71 patients with suspected cerebral amyloid angiopathy markers (regardless of the presence of deep and cerebellar microbleeds) into 4 groups according to microbleed distribution: L (strictly lobar cerebral, n=33), L/LCbll (strictly lobar cerebral and strictly lobar cerebellar microbleeds, n=13), L/Cbll/D (lobar, cerebellar, and deep microbleeds, n=17), and L/D (lobar and deep, n=8). We additionally categorized patients with cerebellar microbleeds into 2 groups according to dentate nucleus involvement: strictly lobar cerebellar (n=16) and dentate (n=14). We then compared clinical characteristics, Aβ (amyloid-β) positivity on PET (positron emission tomography), magnetic resonance imaging cerebral amyloid angiopathy markers, and cerebral small vessel disease burden among groups.

RESULTS

The frequency of Aβ positivity was higher in the L and L/LCbll groups (81.8% and 84.6%) than in the L/Cbll/D and L/D groups (37.5% and 29.4%; P<0.001), while lacune numbers were lower in the L and L/LCbll groups (1.7±3.3 and 1.7±2.6) than in the L/Cbll/D and L/D groups (8.0±10.3 and 13.4±17.7, P=0.001). The L/LCbll group had more lobar cerebral microbleeds than the L group (93.2±121.8 versus 38.0±40.8, P=0.047). The lobar cerebellar group had a higher Aβ positivity (75% versus 28.6%, P=0.011) and lower lacune number (2.3±3.7 versus 8.6±1.2, P=0.041) than the dentate group.

CONCLUSIONS

Strictly lobar cerebral and cerebellar microbleeds are related to cerebral amyloid angiopathy, whereas any combination of concurrent lobar and deep microbleeds suggest hypertensive angiopathy regardless of cerebral or cerebellar compartments.

Prediction of amyloid β PET positivity using machine learning in patients with suspected cerebral amyloid angiopathy markers

Amyloid-β(Aβ) PET positivity in patients with suspected cerebral amyloid angiopathy (CAA) MRI markers is predictive of a worse cognitive trajectory, and it provides insights into the underlying vascular pathology (CAA vs. hypertensive angiopathy) to facilitate prognostic prediction and appropriate treatment decisions. In this study, we applied two interpretable machine learning algorithms, gradient boosting machine (GBM) and random forest (RF), to predict Aβ PET positivity in patients with CAA MRI markers. In the GBM algorithm, the number of lobar cerebral microbleeds (CMBs), deep CMBs, lacunes, CMBs in dentate nuclei, and age were ranked as the most influential to predict Aβ positivity. In the RF algorithm, the absence of diabetes was additionally chosen. Cut-off values of the above variables predictive of Aβ positivity were as follows: (1) the number of lobar CMBs > 16.4(GBM)/14.3(RF), (2) no deep CMBs(GBM/RF), (3) the number of lacunes > 7.4(GBM/RF), (4) age > 74.3(GBM)/64(RF), (5) no CMBs in dentate nucleus(GBM/RF). The classification performances based on the area under the receiver operating characteristic curve were 0.83 in GBM and 0.80 in RF. Our study demonstrates the utility of interpretable machine learning in the clinical setting by quantifying the relative importance and cutoff values of predictive variables for Aβ positivity in patients with suspected CAA markers.

Microangiopathy underlying mixed-location intracerebral hemorrhages/microbleeds: A PiB-PET study

OBJECTIVE

To test the hypothesis that patients with concomitant lobar and deep intracerebral hemorrhages/microbleeds (mixed ICH) have predominantly hypertensive small vessel disease (HTN-SVD) rather than cerebral amyloid angiopathy (CAA), using in vivo amyloid imaging.

METHODS

Eighty Asian patients with primary ICH without dementia were included in this cross-sectional study. All patients underwent brain MRI and 11C-Pittsburgh compound B (PiB)-PET imaging. The mean cortical standardized uptake value ratio (SUVR) was calculated using cerebellum as reference. Forty-six patients (57.5%) had mixed ICH. Their demographic and clinical profile as well as amyloid deposition patterns were compared to those of 13 patients with CAA-ICH and 21 patients with strictly deep microbleeds and ICH (HTN-ICH).

RESULTS

Patients with mixed ICH were younger (62.8 ± 11.7 vs 73.3 ± 11.9 years in CAA, p = 0.006) and showed a higher rate of hypertension than patients with CAA-ICH (p < 0.001). Patients with mixed ICH had lower PiB SUVR than patients with CAA (1.06 [1.01-1.13] vs 1.43 [1.06-1.58], p = 0.003). In a multivariable logistic regression model, mixed ICH was associated with hypertension (odds ratio 8.9, 95% confidence interval 1.4-58.4, p = 0.02) and lower PiB SUVR (odds ratio 0.03, 95% confidence interval 0.001-0.87, p = 0.04) compared to CAA after adjustment for age. Compared to HTN-ICH, mixed ICH showed a similar mean age (62.8 ± 11.7 vs 60.1 ± 14.5 years in HTN-ICH) and risk factor profile (all p > 0.1). Furthermore, PiB SUVR did not differ between mixed ICH (values presented above) and HTN-ICH (1.10 [1.00-1.16], p = 0.45).

CONCLUSIONS

Patients with mixed ICH have much lower amyloid load than patients with CAA-ICH, while being similar to HTN-ICH. Overall, mixed ICH is probably caused by HTN-SVD, an important finding with clinical relevance.

Updates on Prevention of Hemorrhagic and Lacunar Strokes

Intracerebral hemorrhage (ICH) and lacunar infarction (LI) are the major acute clinical manifestations of cerebral small vessel diseases (cSVDs). Hypertensive small vessel disease, cerebral amyloid angiopathy, and hereditary causes, such as Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), constitute the three common cSVD categories. Diagnosing the underlying vascular pathology in these patients is important because the risk and types of recurrent strokes show significant differences. Recent advances in our understanding of the cSVD-related radiological markers have improved our ability to stratify ICH risk in individual patients, which helps guide antithrombotic decisions. There are general good-practice measures for stroke prevention in patients with cSVD, such as optimal blood pressure and glycemic control, while individualized measures tailored for particular patients are often needed. Antithrombotic combinations and anticoagulants should be avoided in cSVD treatment, as they increase the risk of potentially fatal ICH without necessarily lowering LI risk in these patients. Even when indicated for a concurrent pathology, such as nonvalvular atrial fibrillation, nonpharmacological approaches should be considered in the presence of cSVD. More data are emerging regarding the presentation, clinical course, and diagnostic markers of hereditary cSVD, allowing accurate diagnosis, and therefore, guiding management of symptomatic patients. When suspicion for asymptomatic hereditary cSVD exists, the pros and cons of prescribing genetic testing should be discussed in detail in the absence of any curative treatment. Recent data regarding diagnosis, risk stratification, and specific preventive approaches for both sporadic and hereditary cSVDs are discussed in this review article.

Atrial Fibrillation for the Neurologist: Preventing both Ischemic and Hemorrhagic Strokes

PURPOSE OF REVIEW

This review aims to help neurologists managing atrial fibrillation (AF) patients who had an ischemic stroke and/or with intracranial hemorrhage (ICH) markers, therefore at high embolic/hemorrhagic risks.

RECENT FINDINGS

Implantable loop recorders have substantially improved the accuracy of AF detection. Recent research yielded a set of powerful neuroimaging markers that can stratify ICH risk. Direct oral anticoagulants (DOAC) are easier to use with a lower ICH risk than warfarin in a general AF population. Finally, the FDA-approved left atrial appendage closure (LAAC) with the WATCHMAN device provides an option without the need for life-long anticoagulation. In this review, we introduce the concept of preventing both ischemic and hemorrhagic strokes in AF patients through accurate AF diagnosis and stratification of both embolic and ICH risks. LAAC can be considered in patients at higher hemorrhagic risks while warfarin/DOAC use should be individualized in the majority of AF patients at a low risk of bleeding.

Mixed-location cerebral hemorrhage/microbleeds: Underlying microangiopathy and recurrence risk

OBJECTIVE

To assess the predominant type of cerebral small vessel disease (SVD) and recurrence risk in patients who present with a combination of lobar and deep intracerebral hemorrhage (ICH)/microbleed locations (mixed ICH).

METHODS

Of 391 consecutive patients with primary ICH enrolled in a prospective registry, 75 (19%) had mixed ICH. Their demographics, clinical/laboratory features, and SVD neuroimaging markers were compared to those of 191 patients with probable cerebral amyloid angiopathy (CAA-ICH) and 125 with hypertensive strictly deep microbleeds and ICH (HTN-ICH). ICH recurrence and case fatality were also analyzed.

RESULTS

Patients with mixed ICH showed a higher burden of vascular risk factors reflected by a higher rate of left ventricular hypertrophy, higher creatinine values, and more lacunes and severe basal ganglia (BG) enlarged perivascular spaces (EPVS) than patients with CAA-ICH (all p < 0.05). In multivariable models mixed ICH diagnosis was associated with higher creatinine levels (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.2-5.0, p = 0.010), more lacunes (OR 3.4, 95% CI 1.7-6.8), and more severe BG EPVS (OR 5.8, 95% CI 1.7-19.7) than patients with CAA-ICH. Conversely, when patients with mixed ICH were compared to patients with HTN-ICH, they were independently associated with older age (OR 1.03, 95% CI 1.02-1.1), more lacunes (OR 2.4, 95% CI 1.1-5.3), and higher microbleed count (OR 1.6, 95% CI 1.3-2.0). Among 90-day survivors, adjusted case fatality rates were similar for all 3 categories. Annual risk of ICH recurrence was 5.1% for mixed ICH, higher than for HTN-ICH but lower than for CAA-ICH (1.6% and 10.4%, respectively).

CONCLUSIONS

Mixed ICH, commonly seen on MRI obtained during etiologic workup, appears to be driven mostly by vascular risk factors similar to HTN-ICH but demonstrates more severe parenchymal damage and higher ICH recurrence risk.

Circulating MicroRNAs as Biomarkers for Acute Ischemic Stroke: A Systematic Review

BACKGROUND

Acute ischemic stroke is a leading cause of death and disability worldwide. Unlike myocardial infarction, there is no current blood test to diagnose acute ischemic stroke. MicroRNAs (miRNAs) are very stable in the blood and have been suggested as potential diagnostic markers.

MATERIALS AND METHODS

This review aimed to systematically assess case-control studies investigating the association of circulating miRNAs with acute ischemic stroke. Medline, CINAHL, Cochrane Library, Web of Science, Scopus, and PubMed were searched for studies that examined the association of circulating miRNAs in patients with acute ischemic stroke. Studies meeting specific inclusion and exclusion criteria (such as blood samples obtained within 24 hours of an acute ischemic stroke) were selected for data extraction. Two authors extracted data from the included studies relevant to the study design, the patient characteristics, and the relative miRNA expression.

RESULTS

Eight studies were included involving 572 cases and 431 healthy controls. Twenty-two miRNAs (12 upregulated and 10 downregulated) were reported as differentially expressed. Only 1 miRNA, miR-106b, was reported as differentially expressed in at least 2 studies. Significant heterogeneity in the design and methods of the included studies was noted.

CONCLUSIONS

Differential expression of a large number of miRNAs has been reported early following acute ischemic stroke. More research is required in larger patient populations to further evaluate the diagnostic potential of the reported miRNAs.