Silent Cerebral Infarcts and Cerebral White Matter Lesions in Patients with Nonvalvular Atrial Fibrillation

Neuroglial Biomarkers for Risk Assessment of Ischemic Stroke and Other Cardiovascular Events in Patients With Atrial Fibrillation Not Receiving Oral Anticoagulation

BACKGROUND

Cardiac biomarkers improve risk prediction in patients with atrial fibrillation (AF). We recently demonstrated that the NFL (neuron-specific protein neurofilament light chain) was associated with ischemic stroke in patients with AF not receiving oral anticoagulation. The association of other neuroglial biomarkers reflecting brain injury (ie, GFAP [glial fibrillary acidic protein], total tau [tau], and UCHL1 [ubiquitin carboxy-terminal hydrolase L1]) with the risk of stroke and other cardiovascular outcomes in AF is unknown.

METHODS AND RESULTS

Baseline plasma samples were available from 967 patients with AF not receiving oral anticoagulation treatment. Concentrations of NFL, GFAP, tau, and UCHL1 were determined with a Single Molecule Array kit (Simoa). Associations between baseline biomarker level, clinical characteristics, and outcomes (ischemic stroke, hospitalization for heart failure, and all-cause death) were analyzed with multivariable Cox regression adjusted for clinical characteristics and other biomarkers. Higher levels of all 4 neuroglial biomarkers were correlated with increasing age and female sex. During a median follow-up of 3.6 years, NFL was associated with increased risk of ischemic stroke (for a doubling in NFL, hazard ratio [HR], 1.27 [95% CI, 1.03-1.56]) and death (HR, 1.46 [95% CI, 1.25-1.70]). In adjusted analyses, GFAP, tau, and UCHL1were not associated with stroke or death. NFL, tau, and UCHL1 were significantly associated with hospitalization for heart failure.

CONCLUSIONS

In patients with AF not receiving oral anticoagulation, NFL was the only neuroglial biomarker significantly and independently associated with the risk of ischemic stroke and death. Further studies evaluating NFL for stroke risk assessment in patients with AF and the impact of contemporary oral anticoagulation treatment are warranted.

Subtle signs of atrial cardiomyopathy and left ventricular diastolic dysfunction are associated with reduced cognitive function: results from the Hamburg City Health Study

BACKGROUND

Atrial fibrillation is associated with cognitive dysfunction. Atrial cardiomyopathy has been correlated with both entities. We aimed to characterize the association of echocardiographic parameters of atrial cardiomyopathy with cognitive function and cerebral changes.

METHODS

Participants of the population-based Hamburg City Health Study underwent in-depth transthoracic echocardiography and cognitive function testing, the Animal Naming Test (ANT), the Trail Making Test A (TMT-A) and B (TMT-B), 10-word learning test and cerebral magnetic resonance imaging.

RESULTS

After excluding individuals with stroke or depression, data from 7852 individuals were available. In multi-variable-adjusted regression analyses, the E/e'-ratio was associated with the level of impairment in the ANT (- 0.19 per one standard deviation [SD] increase, 95% confidence interval [CI] - 0.36-[- 0.01]) and the TMT-A (0.01 per one SD increase, 95% CI 0.003-0.020). Left atrial global peak strain was associated with positive performance in the TMT-A and B (-0.01 per one SD increase [95% CI - 0.02-(- 0.002)] and - 0.02 per one SD increase [95% CI - 0.03-(- 0.01)], respectively) and the immediate recall of the 10-word learning test (0.11 per one SD increase, 95% CI 0.02-0.20). The E/e'-ratio was positively associated with the total and periventricular white matter hyperintensity load in age- and sex-adjusted regression analyses though statistical significance was lost after multi-variable adjustment.

CONCLUSIONS

Subclinical echocardiographic signs of atrial cardiomyopathy and left ventricular diastolic dysfunction are associated with impaired performance in cognitive tests in the population. Our data provide evidence of the clinically important cardio-cerebral axis, relating cardiac dysfunction with cognitive performance.

Equol Nonproducing Status as an Independent Risk Factor for Acute Cardioembolic Stroke and Poor Functional Outcome

Background/Objectives: Equol has protective effects against coronary artery disease and dementia by strongly binding to estrogen receptor beta, whereas the intake of soy isoflavone alone does not always confer such protective effects. Equol production is completely dependent on the existence of equol-producing gut microbiota. The effects of equol-producing status on the cerebrovascular diseases remain unclear. The current study was aimed to investigate the association of equol-producing status with the development of stroke and its neurological prognosis. Methods: Frequencies of equol producers were compared between healthy subjects (HS) registered in the Suita Study and patients with acute stroke admitted to our stroke center from September 2019 to October 2021 in a retrospective cohort study. Results: The proportion of HSs and patients with ischemic stroke who were equol producers did not significantly differ (50/103 [48.5%] vs. 60/140 [42.9%], p = 0.38). However, cardioembolic stroke was significantly associated with low a prevalence of equol producers (adjusted odds ratio [aOR] 0.46, 95% confidence interval [CI] 0.21-0.99, p = 0.05). A higher left atrial volume index was observed in equol nonproducers (46.3 ± 23.8 vs. 36.0 ± 11.6 mL/m2, p = 0.06). The equol nonproducers had a significantly higher prevalence of atrial fibrillation than the equol producers (27.5% vs. 13.3%, p = 0.04). Furthermore, the equol producers exhibited a significantly favorable functional outcome upon discharge (aOR 2.84, 95% CI 1.20-6.75, p = 0.02). Conclusions: Equol is a promising candidate for interventions aiming to reduce the risk of CES and atrial dysfunction, such as atrial fibrillation and improve neurological prognosis after ischemic stroke.

Vagus nerve size determined via ultrasonography is associated with white matter lesions in patients with vascular risk factors

PURPOSE

The cross-sectional area (CSA) of the cervical vagus nerve (VN), as assessed through ultrasonography, might be linked to autonomic nervous system dysfunction. Hypertension is the primary factor associated with cerebral white matter lesions (WMLs), but there is also evidence of a connection with autonomic nervous system dysfunction. However, the associations between WMLs and VN size are unclear. Our objective was to investigate the associations between WMLs and VN size in patients with vascular risk factors.

METHODS

The CSA of the VN was evaluated using carotid ultrasonography in patients with a history of stroke (acute or chronic) and comorbidities (n = 196, 70.2 ± 12.7 years). Common carotid artery (CCA) intima-media thickness and interadventitial diameter (IAD) were also measured. The severity of the WMLs was assessed by the Fazekas classification and Scheltens' scale.

RESULTS

The CSA of the right VN (2.08 ± 0.65 mm2) was significantly greater than that of the CSA of the left VN (1.56 ± 0.44 mm2) (P < 0.001). Multiple linear regression analyses revealed that older age, hypertension, increased right CCA IAD, and decreased CSA of the right VN (standardized partial regression coefficient [β] - 0.226; P < 0.001) were independently associated with the severity of WMLs (Scheltens' scale). A decreased CSA of the left VN was also associated with the severity of WMLs (β = - 0.239; P < 0.001).

CONCLUSION

VN size determined via ultrasonography was associated with the severity of WMLs. While these findings do not establish a causal relationship, they suggest that autonomic nervous system dysfunction is involved in the progression of WMLs.

Direct oral anticoagulants vs vitamin K antagonist on dementia risk in atrial fibrillation: systematic review with meta-analysis

Oral anticoagulation significantly reduces the incidence of dementia in atrial fibrillation patients. However, this protective effect has not been compared between Direct Oral Anticoagulants (DOAC) and Vitamin K antagonists' anticoagulants (VKA). We conducted an electronic search for potentially eligible studies through the bibliographic databases MEDLINE, CENTRAL, ClinicalTrials.gov, EMBASE and Web of Science. The outcome of interest was dementia. Random-effects meta-analysis was performed. Nine observational studies were included and 1,175,609 atrial fibrillation patients were enrolled. DOAC therapy was associated with a significant reduction when compared with patients under VKA therapy (hazard ratio 0.89; 95% confidence interval 0.80-0.99). The grade of confidence of our results was very low due to the risk of bias. DOAC therapy is associated with a significant decrease in the risk of dementia when compared with VKA therapy. However, the low certainty of the evidence along with the paucityof clinical trials dedicated to answering this important question underscores a need for global clinical research initiatives.

Heart-brain connections: Phenotypic and genetic insights from magnetic resonance images

Cardiovascular health interacts with cognitive and mental health in complex ways, yet little is known about the phenotypic and genetic links of heart-brain systems. We quantified heart-brain connections using multiorgan magnetic resonance imaging (MRI) data from more than 40,000 subjects. Heart MRI traits displayed numerous association patterns with brain gray matter morphometry, white matter microstructure, and functional networks. We identified 80 associated genomic loci (P < 6.09 × 10-10) for heart MRI traits, which shared genetic influences with cardiovascular and brain diseases. Genetic correlations were observed between heart MRI traits and brain-related traits and disorders. Mendelian randomization suggests that heart conditions may causally contribute to brain disorders. Our results advance a multiorgan perspective on human health by revealing heart-brain connections and shared genetic influences.

Racial/Ethnic Variation in White Matter Hyperintensity Progression in the ACCORDION MIND Study

BACKGROUND

White matter hyperintensities (WMHs) are linked to cognitive decline and stroke. We investigate the impact of race on WMH progression in the Action to Control Cardiovascular Risk in Diabetes Memory in Diabetes (ACCORDION MIND) trial.

MATERIALS AND METHODS

The primary outcome is WMH progression in milliliters, evaluated by fitting linear regression to WMH volume on the month 80 magnetic resonance imaging (MRI) and including the WMH volume on the baseline MRI. The primary predictor is patient race, with the exclusion of patients defined as "other" race. We also derived predicted probabilities of our outcome for systolic blood pressure (SBP) levels.

RESULTS

We included 276 patients who completed the baseline and month 80 MRI, of which 207 (75%) were White, 48 (17%) Black, and 21 (8%) Hispanic. During follow-up, the mean number of SBP, low-density lipoprotein (LDL), and A1c measurements per patient was 21, 8, and 15. The median (IQR) WMH progression was 1.5 mL (0.5 to 3.9) for Black patients, 1.0 mL (0.4 to 4.0) for Hispanics, and 1.3 mL (0.5 to 2.7) for Whites (Kruskal-Wallis test, P =0.59). In the multivariate regression model, Black, compared with White, patients had significantly more WMH progression (β Coefficient 1.26, 95% confidence interval 0.45 to 2.06, P =0.002). Hispanic, compared with White, patients neither have significantly different WMH progression ( P =0.392), nor was there a difference when comparing Hispanic to Black patients ( P =0.162). The predicted WMH progression was significantly higher for Black compared with White patients across a mean SBP of 117 to 139 mm Hg.

CONCLUSIONS

Black diabetic patients in Action to Control Cardiovascular Risk in Diabetes Memory in Diabetes (ACCORDION MIND) have a higher risk of WMH progression than White patients across a normal range of SBP.

Neurologic Biomarkers, Neuroimaging, and Cognitive Function in Persistent Atrial Fibrillation: A Cross-Sectional Study

The aim of this study was to evaluate the specific neurologic biomarkers, neuroimaging findings, and cognitive function in patients with persistent atrial fibrillation (AF) undergoing electrical cardioversion, compared to control subjects. This cross-sectional study included 25 patients with persistent AF undergoing electrical cardioversion and 16 age- and sex-matched control subjects. Plasma levels of glial fibrillary acidic protein (GFAP), neurofilament light protein (NFL), and ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), as well as parameters of neuroimaging and cognitive function, were compared between the groups. Neuroimaging was performed using the standard magnetic resonance imaging (MRI) protocol. Cognitive function was assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) Cognitive Function Index. Further analysis of neurologic biomarkers was performed based on the subsequent electrical cardioversion. There was no significant difference in GFAP (median of 24.7 vs. 28.7 pg/mL, p = 0.347), UCH-L1 (median of 112.8 vs. 117.7 pg/mL, p = 0.885), and NFL (median of 14.2 vs. 15.4 pg/mL, p = 0.886) levels between AF patients and control subjects. Similarly, neuroimaging showed no between-group difference in large cortical and non-cortical lesions (n = 2, 8.0% vs. n = 0, 0.0%, p = 0.246), small non-cortical lesions (n = 5, 20.0% vs. n = 5, 31.3%, p = 0.413), white matter hyperintensity (n = 23, 92.0% vs. n = 14, 87.5%, p = 0.636), and thromboembolic lesions (n = 0, 0.0% vs. n = 1, 6.3%, p = 0.206). Cognitive assessment did not show any between-group difference in the PROMIS index (52.2 ± 9.6 vs. 51.2 ± 6.2, p = 0.706). Finally, there were no significant dynamics in neurologic biomarkers following electrical cardioversion (p > 0.05). This hypothesis-generating study did not find a significant difference in neurologic biomarkers, neuroimaging findings, or cognitive function between patients with persistent AF and controls. The restoration of sinus rhythm was not significantly associated with a change in neurologic biomarkers. Further powered longitudinal studies are needed to re-assess these findings in an AF population.

Relationships between cerebral small vessel diseases markers and cognitive performance in stroke-free patients with atrial fibrillation

Background

Atrial fibrillation (AF) is related to an increased risk of cognitive dysfunction. Besides clinically overt stroke, AF can damage the brain via several pathophysiological mechanisms. We aimed to assess the potential mediating role of cerebral small vessel disease (SVD) and cognitive performance in individuals with AF.

Methods

Stroke-free individuals with AF from the cardiological outpatient clinic at West China Hospital of Sichuan University were recruited. Extensive neuropsychological testing tools were assessed including global function, domains of attention, executive functions, learning, and memory. 3 T magnetic resonance imaging (MRI) was used for SVD markers assessment of white matter hyperintensities (WMH), lacunes, cerebral microbleeds (CMBs), and enlarged perivascular spaces (EPVS). The correlation between SVD markers and cognitive measures was analyzed by multivariate linear regression models.

Results

We finally enrolled 158 participants, of whom 95 (60.1%) were males. In multivariate models, the presence of lacunes independently associated with Montreal Cognitive Assessment (Model 1: ß = 0.52, Model 2: ß = 0.55), Rey Auditory Verbal Learning Test-immediate and delayed recall (Model 1: ß = 0.49; ß = 0.69; Model 2: ß = 0.53; ß = 0.73) as well as Stroop-A_correct (Model 1: ß = 0.12; Model 2: ß = 0.13), while total WMH severity independently associated with Stroop_time-A (Model 1: ß = 0.24; Model 3: ß = 0.27), Stroop_time-B (Model 1: ß = 0.17; Model 3: ß = 0.17), Stroop_time-C (Model 1: ß = 0.22; Model 3: ß = 0.21) and Shape Trail Test-A (Model 1: ß = 0.17; Model 3: ß = 0.16).

Conclusion

In our cohort of stroke-free individuals with AF, lacunes, and WMHs were independently associated with cognitive decline while EPVS and CMBs did not show significance. Assessment of SVD MRI markers might be valuable for cognition risk stratification and facilitate optimal management of patients with AF.

Serum Neurofilament Light Chain in Patients With Atrial Fibrillation

Background

Atrial fibrillation (AF) is associated with stroke and MRI features of cerebral tissue damage but its impact on levels of serum neurofilament light chain (sNFL), an established biochemical marker of neuroaxonal damage, is unknown.

Methods and Results

In this observational study, sNFL was analyzed in 280 patients with AF and 280 controls without AF matched for age, sex, and diabetes status within the STABILITY (Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy) trial. None of the patients had a history of previous stroke or transient ischemic attack. Patients with a diagnosis of AF were divided into two groups based on if they were in AF rhythm at the time of blood sampling (AF ECG+, n=74), or not (AF ECG−, n=206). Multiple linear regression analysis was performed to adjust for clinical risk factors. In patients with AF, the levels of sNFL were 15% (AF ECG+) and 10% (AF ECG−) higher than in the control group after adjustment for clinical risk factors, P =0.047 and 0.04, respectively. There was no association between anticoagulation treatment and sNFL levels.

Conclusions

sNFL was elevated in patients with AF compared with matched controls without AF. Ongoing AF rhythm was associated with even higher levels of sNFL than in patients with a diagnosis of AF but currently not in AF rhythm. Anticoagulation treatment did not affect sNFL levels.

Trial Registration

ClinicalTrials.gov NCT00799903.

Silent Brain Infarction, Delirium, and Cognition in Three Invasive Cardiovascular Procedures: a Systematic Review

Silent brain infarctions (SBIs) are brain lesions noted on neuroimaging that are not associated with clinical symptoms. SBIs are associated with a number of vascular risk factors and are common following invasive cardiovascular procedures such as atrial fibrillation (AF) ablation, coronary artery bypass graft (CABG), and transcatheter aortic valve replacement (TAVR). Although not eliciting signs of clinical stroke, SBIs are associated with increased frailty, and motor and mood features. Less is known, however, about the relationship between SBI, cognition, and delirium following invasive cardiac procedures and most investigations into these relationships have been reported in large-scale epidemiological studies. In the current paper, we conducted a systematic review to evaluate evidence of a relationship between SBI, delirium, and cognitive decline following CABG, AF ablation, and TAVR. Twenty studies met inclusion criteria. In general, our review identified conflicting results for each cardiac procedure, with some studies suggesting a relationship between SBI, cognitive impairment, and delirium, whereas others showed no relationship between SBI, cognitive impairment, and delirium. Potential reasons for this discrepancy as well as suggestions for future research are discussed.

Evaluating the Potential Pathology and Short-Term Outcomes of Cryptogenic Stroke Using the Etiological Classification System

AIM

Various embolic sources and pathogenetic mechanisms underlie cryptogenic stroke (CS). We investigated the association of etiological diversity with short-term outcomes in patients with CS using a modified atherosclerosis (A), small-vessel disease (S), cardiac pathology (C), other causes (O), and dissection (D) (ASCOD) system.

METHODS

Patients with CS who underwent transesophageal echocardiography were registered in this multicenter, observational study. In the modified classification system, O and D were inapplicable and thus excluded. Instead, atherosclerosis, small-vessel disease, cardiac pathology-CS classification was specifically constructed for the etiological diagnosis of CS. We utilized this system to explore the mechanism of CS by grading each pathology and evaluated its association with poorer modified Rankin Scale scores of 3-6 at hospital discharge.

RESULTS

A total of 672 patients (68.7±12.8 years, 220 females) were analyzed. In the multiple logistic regression model, female sex (odds ratio [OR], 1.87 [1.15-3.04]; P=0.012), body mass index (OR, 0.93 [0.88-0.99]; P=0.025), National Institute of Health Stroke Scale score (OR, 1.16 [1.12-1.21]; P＜0.001), CHADS2 score (OR, 1.56 [1.30-1.86]; P＜0.001), D-dimer (OR, 1.04 [1.01-1.08]; P=0.015), diffusion-weighted image (DWI) lesion size (OR, 1.44 [1.10-1.89]; P=0.009), and S＋C score (OR, 1.26 [1.03-1.56]; P=0.029) were associated with poor functional outcome at discharge whereas the S＋C score was marginally associated with poor functional outcome after excluding 137 patients with a premorbid modified Rankin Scale score of ≥ 3.

CONCLUSIONS

The coexistence of small-vessel disease and cardiac pathology might be associated with poor in-hospital functional outcome in CS.

Comparison of frequency of silent cerebral infarction as assessed by serum neuron specific enolase in patients with non-valvular atrial fibrillation: Warfarin versus direct oral anticoagulant

BACKGROUND

Cerebral infarction in patients with atrial fibrillation (AF) may clinically vary from being silent to catastrophic. Silent cerebral infarction (SCI) is the neuronal injury in the absence of clinically appearent stroke or transient ischaemic attack. Serum neuron specific enolase (NSE) is suggested to be a valid surrogate biomarker that allows to detect recent neuronal injury. We aimed to evaluate the incidence of recent SCI by positive NSE levels in patients with non-valvular AF (NVAF) on oral anticoagulants.

METHODS

Blood samples for NSE were collected from 197 consecutive NVAF patients. NSE levels of greater than 12 ng/ml was considered as positive and suggestive of SCI.

RESULTS

Patients were mainly female with a mean age of 69 years. Ninety-eight of them (49.7%) were taking warfarin. Mean INR level was 2.3 ± 0.9. Mean CHA₂DS₂-VASc score of the study population was 3.5 ± 1.5. Seventy-two patients (36.5%) were found to have NSE elevation. They were more likely to have history of chronic heart failure and previous stroke/TIA. Increased left atrial diameter and higher CHA₂DS₂-VASc were other factors associated with SCI. Patients on DOACs and patients taking aspirin on top of oral anticoagulant treatment were less likely to have SCI. Multivariate analysis demonstrated that increased left atrial diameter (OR: 2.5; 95% CI: 1.52-4; p < 0.001) and use of warfarin (OR: 2.8; 95% CI: 1.37-5.61; p = 0.005) were detected as independent predictors of SCI.

CONCLUSIONS

Our study revealed that DOACs were associated with significantly reduced SCIs compared with warfarin, probably due to more effective and consistent therapeutic level of anticoagulation.

Predictive role of atrial fibrillation in cognitive decline: a systematic review and meta-analysis of 2.8 million individuals

Aims

To systematic review and meta-analyse the association and mechanistic links between atrial fibrillation (AF) and cognitive impairment.

Methods and results

PubMed, EMBASE, and Cochrane Library were searched up to 27 March 2021 and yielded 4534 citations. After exclusions, 61 were analysed; 15 and 6 studies reported on the association of AF and cognitive impairment in the general population and post-stroke cohorts, respectively. Thirty-six studies reported on the neuro-pathological changes in patients with AF; of those, 13 reported on silent cerebral infarction (SCI) and 11 reported on cerebral microbleeds (CMB). Atrial fibrillation was associated with 39% increased risk of cognitive impairment in the general population [n = 15: 2 822 974 patients; hazard ratio = 1.39; 95% confidence interval (CI) 1.25–1.53, I² = 90.3%; follow-up 3.8–25 years]. In the post-stroke cohort, AF was associated with a 2.70-fold increased risk of cognitive impairment [adjusted odds ratio (OR) 2.70; 95% CI 1.66–3.74, I² = 0.0%; follow-up 0.25–3.78 years]. Atrial fibrillation was associated with cerebral small vessel disease, such as white matter hyperintensities and CMB (n = 8: 3698 patients; OR = 1.38; 95% CI 1.11–1.73, I² = 0.0%), SCI (n = 13: 6188 patients; OR = 2.11; 95% CI 1.58–2.64, I² = 0%), and decreased cerebral perfusion and cerebral volume even in the absence of clinical stroke.

Conclusion

Atrial fibrillation is associated with increased risk of cognitive impairment. The association with cerebral small vessel disease and cerebral atrophy secondary to cardioembolism and cerebral hypoperfusion may suggest a plausible link in the absence of clinical stroke. PROSPERO CRD42018109185.

Recent-onset atrial fibrillation: a study exploring the elements of Virchow's triad after cardioversion

Purpose

Atrial fibrillation (AF) imposes an inherent risk for stroke and silent cerebral emboli, partly related to left atrial (LA) remodeling and activation of inflammatory and coagulation systems. The aim was to explore the effects of cardioversion (CV) and short-lasting AF on left atrial hemodynamics, inflammatory, coagulative and cardiac biomarkers, and the association between LA functional recovery and the presence of a prior history of AF.

Methods

Patients referred for CV within 48 h after AF onset were prospectively included. Echocardiography and blood sampling were performed immediately prior, 1–3 h after, and at 7–10 days after CV. The presence of chronic white matter hyperintensities (WMH) on magnetic resonance imaging was related to biomarker levels.

Results

Forty-three patients (84% males), aged 55±9.6 years, with median CHA₂DS₂-VASc score 1 (IQR 0–1) were included. The LA emptying fraction (LAEF), LA peak longitudinal strain during reservoir, conduit, and contractile phases improved significantly after CV. Only LAEF normalized within 10 days. Interleukin-6, high-sensitivity cardiac-troponin-T (hs-cTNT), N-terminal-pro-brain-natriuretic peptide, prothrombin-fragment 1+2 (PTf1+2), and fibrinogen decreased significantly after CV. There was a trend towards higher C-reactive protein, hs-cTNT, and PTf1+2 levels in patients with WMH (n=21) compared to those without (n=22). At 7–10 days, the LAEF was significantly lower in patients with a prior history of AF versus those without.

Conclusion

Although LA stunning resolved within 10 days, LAEF remained significantly lower in patients with a prior history of AF versus those without. Inflammatory and coagulative biomarkers were higher before CV, but subsided after 7–10 days, which altogether might suggest an enhanced thrombogenicity, even in these low-risk patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-021-01078-9.

Atrial Fibrillation, Stroke, and Silent Cerebrovascular Disease: A Population-based MRI Study

Background and Objectives

Atrial fibrillation (AF) has been associated with cognitive decline and dementia. However, the mechanisms behind these associations are not clear. Examination of cerebrovascular pathology on MRI may shed light on how AF affects the brain. This study aimed to determine whether AF is associated with a broad range of cerebrovascular diseases beyond the well-known association with symptomatic stroke, including silent infarcts and markers of small vessel disease, i.e., cerebral microbleeds (CMBs), white matter hyperintensities (WMHs), and lacunes, in a population-based sample of 70-year-olds.

Methods

Data were obtained from the Gothenburg H70 Birth Cohort Studies, in which individuals are invited based on birthdate. This study has a cross-sectional design and includes individuals born in 1944 who underwent structural brain MRI in 2014 to 2017. AF diagnoses were based on self-report, ECG, and register data. Symptomatic stroke was based on self-report, proxy interviews, and register data. Brain infarcts and CMBs were assessed by a radiologist. WMH volumes were measured on fluid-attenuated inversion recovery images with the Lesion Segmentation Tool. Multivariable logistic regression was used to study the association between AF and infarcts/CMBs, and multivariable linear regression was used to study the association between AF and WMHs.

Results

A total of 776 individuals were included, and 65 (8.4%) had AF. AF was associated with symptomatic stroke (odds ratio [OR] 4.5, 95% confidence interval [CI] 2.1–9.5) and MRI findings of large infarcts (OR 5.0, 95% CI 1.5–15.9), lacunes (OR 2.7, 95% CI 1.2–5.6), and silent brain infarcts (OR 3.5; 95% CI 1.6–7.4). Among those with symptomatic stroke, individuals with AF had larger WMH volumes (0.0137 mL/total intracranial volume [TIV], 95% CI 0.0074–0.0252) compared to those without AF (0.0043 mL/TIV, 95% CI 0.0029–0.0064). There was no association between AF and WMH volumes among those without symptomatic stroke. In addition, AF was associated to CMBs in the frontal lobe.

Discussion

AF was associated with a broad range of cerebrovascular pathologies. Further research is needed to establish whether cerebrovascular MRI markers can be added to current treatment guidelines to further personalize anticoagulant treatment in patients with AF and to further characterize the pathogenetic processes underlying the associations between AF and cerebrovascular diseases, as well as dementia.

Emerging role of white matter lesions in cerebrovascular disease

White matter lesions have been implicated in the setting of stroke, dementia, intracerebral haemorrhage, several other cerebrovascular conditions, migraine, various neuroimmunological diseases like multiple sclerosis, disorders of metabolism, mitochondrial diseases and others. While much is understood vis a vis neuroimmunological conditions, our knowledge of the pathophysiology of these lesions, and their role in, and implications to, management of cerebrovascular diseases or stroke, especially in the elderly, are limited. Several clinical assessment tools are available for delineating white matter lesions in clinical practice. However, their incorporation into clinical decision-making and specifically prognosis and management of patients is suboptimal for use in standards of care. This article sought to provide an overview of the current knowledge and recent advances on pathophysiology, as well as clinical and radiological assessment, of white matter lesions with a focus on its development, progression and clinical implications in cerebrovascular diseases. Key indications for clinical practice and recommendations on future areas of research are also discussed. Finally, a conceptual proposal on putative mechanisms underlying pathogenesis of white matter lesions in cerebrovascular disease has been presented. Understanding of pathophysiology of white matter lesions and how they mediate outcomes is important to develop therapeutic strategies.

Incidence and Risk Factors for Silent Brain Infarction After On-Pump Cardiac Surgery: A Meta-analysis and Meta-regression of 29 Prospective Cohort Studies

BACKGROUND

Silent brain infarction (SBI) happens at a considerable rate after on-pump cardiac surgery. Though termed silent, SBI is related to unfavorable clinical outcomes including higher incidence of future stroke and neurocognitive impairment in the general population. The risk factors of SBI have not been fully identified in both individual studies and several meta-analyses addressing the topic. In this meta-analysis, we aimed to conduct meta-regression analysis for the first time to explore risk factors for SBI after on-pump cardiac surgery.

METHODS

This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Medline, Embase, Central, Web of Science, and Wiley databases were searched for relevant studies. Preoperative patient baseline characteristics and intraoperative surgical parameters were extracted from included studies. For meta-regression, a P value of less than 0.1 was considered statistically significant in both univariable and multivariable analyses.

RESULTS

Twenty-nine studies with 1478 patients were included in this meta-analysis. The summarized SBI rate after on-pump cardiac surgery was 37% (95% CI 0.27-0.47, P < 0.0001). Heterogeneity between studies was significant (I2 = 94.9%, P < 0.0001). In multivariable meta-regression, we found that age (coefficient 0.014, 95% CI 0.001-0.029, P = 0.043), diabetes (coefficient 0.006, 95% CI - 0.001 to 0.013, P = 0.075), and proportion of CABG (coefficient - 0.001, 95% CI - 0.003 to 0.0003, P = 0.096) were significantly associated with SBI incidence.

CONCLUSION

From the meta-regression, we concluded that advanced age and diabetes were related to increased SBI incidence after on-pump cardiac surgery, while CABG procedure alone was associated with less SBI onset. Studies with more accurate diagnoses of SBI are required to add more conclusive evidence to the field.

Difference in risk factors of silent brain infarction between paroxysmal and persistent atrial fibrillation

•

Differences in risk factors for SBI between paroxysmal and persistent AF was studied.

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NVAF patients (119 paroxysmal, 71 persistent) underwent brain MRI, TTE, and TEE.

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DM and CKD, which represents microvascular disease, predicted SBI in paroxysmal AF.

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There was no obvious therapeutic target for SBI after progression to persistent NVAF.

•

Intervention for DM and CKD from paroxysmal NVAF may prevent SBI and future stroke.

Background

Although silent brain infarction is an independent risk factor for subsequent symptomatic stroke and dementia in patients with nonvalvular atrial fibrillation, little is known regarding differences in risk factors for silent brain infarction between patients with paroxysmal and persistent nonvalvular atrial fibrillation.

Methods

This study population consisted of 190 neurologically asymptomatic patients (mean age, 64 ± 11 years) with nonvalvular atrial fibrillation (119 paroxysmal, 71 persistent) who were scheduled for catheter ablation. All patients underwent brain magnetic resonance imaging to screen for silent brain infarction prior to ablation. Transthoracic and transesophageal echocardiography was performed to screen for left atrial abnormalities (left atrial enlargement, spontaneous echo contrast, or left atrial appendage emptying velocity) and complex plaques in the aortic arch.

Results

Silent brain infarction was detected in 50 patients (26%) [26 patients (22%) in paroxysmal vs. 24 patients (34%) in persistent, p = 0.09]. Multiple logistic regression analysis indicated that age and diabetes mellitus or chronic kidney disease (estimated glomerular filtration rate < 60 mL/min/1.73 m²) were associated with silent brain infarction in patients with paroxysmal nonvalvular atrial fibrillation (p < 0.05), whereas no modifiable risk factors of silent brain infarction were observed in patients with persistent nonvalvular atrial fibrillation.

Conclusions

These findings suggest that intensive intervention for diabetes mellitus and renal impairment from the paroxysmal stage or ablation therapy at the time of paroxysmal stage to prevent progression to persistent nonvalvular atrial fibrillation may prevent silent brain infarction and consequently reduce the risk of future symptomatic stroke.

Serial Magnetic Resonance Imaging after Electrical Cardioversion of Recent Onset Atrial Fibrillation in Anticoagulant-Naïve Patients - A Prospective Study Exploring Clinically Silent Cerebral Lesions

Background

Patients with atrial fibrillation (AF) have a high incidence of cognitive impairment, which may be related to clinically silent microembolism causing cerebral infarctions.

Objective

To explore the occurrence and timing of silent brain lesions following electrical cardioversion (CV) of recent onset AF in anticoagulant-naïve patients and to study related effects on cognitive function and biomarkers of cerebral damage, S100b.

Methods

Patients with AF duration > 48 hours were prospectively included. Brain magnetic resonance imaging (MRI) and S100b, were obtained prior, after and 7-10 days following CV. Trail making tests (TMT-A and TMT-B) and their difference, ΔΤΜΤ, were assessed prior to CV, 7-10 days and 30 days after CV.

Results

Forty-three patients (84% males) with median CHA2DS2-VASc score 1 (interquartile range 0-1) were included. Sequential MRI, including diffusion weighted scans, showed no new brain lesions after CV. Chronic white matter hyperintensities were present at baseline in 21/43 (49%) patients. The S100b (µg/l) levels increased significantly from baseline, (mean ±SD) 0.0472±0.0182 to 0.0551±0.0185 after CV, p=0.001 and then decreased 7-10 days after CV to 0.0450±0.0186, p <.;0.001. Consecutive TMT scores improved successively after CV, being statistically and clinically significant for TMT-B (p<0.01) and ΔΤΜΤ (p=0.005) between 7-10 days and 30 days after CV (Reliable Change Index >1.96).

Conclusions

New brain lesions could not be detected on MRI after CV, but the high incidence of white matter hyperintensities and the transient increase in S100b may indicate transient or minor brain damage undetectable by MRI thus heightening the need to reevaluate thromboembolic risk prior to CV even in low risk patients.

Pilot Investigation: Older Adults With Atrial Fibrillation Demonstrate Greater Brain Leukoaraiosis in Infracortical and Deep Regions Relative to Non-Atrial Fibrillation Peers

Background

This pilot study explored differences in distribution of white matter hyperintensities (called leukoaraiosis; LA) in older adults (mean age = 67 years) with atrial fibrillation (AF) vs. non-AF peers measured by: (1) depth distribution; (2) anterior-posterior distribution; (3) associations between LA and cortical thickness; and (4) presence of lacunae and stroke.

Methods

Participant data (AF n = 17; non-AF peers n = 17) were acquired with the same magnetic resonance imaging protocols. LA volume was quantified by cortical depth (periventricular, deep, infracortical) and in anterior and posterior regions. Cortical thickness by lobe was assessed relative to LA load.

Results

Relative to non-AF peers, the AF group had twice the total LA volume (AF = 2.1% vs. Non-AF = 0.9%), over 10 times greater infracortical LA (AF = 0.72% vs. Non-AF = 0.07%), and three times greater deep LA (AF = 2.1% vs. Non-AF = 0.6%). Examinations of the extent of LA in anterior vs. posterior regions revealed a trend for more posterior relative to anterior LA. In the entire sample, total LA and infracortical LA were negatively associated with temporal lobe thickness. Only those with AF presented with lacunae or stroke.

Conclusion

Aging adults with AF had more total white matter disease than those without AF, particularly near the cortical mantle and deep within the cortex. Total and infracortical white matter disease in the entire sample negatively associated with temporal lobe thickness. Results suggest that those with AF have a distinct pattern of LA relative to those without AF, and that LA severity for all individuals may associate with structural changes in the cortex.

Association of White Matter Hyperintensities and Cardiovascular Disease: The Importance of Microcirculatory Disease

Cardiac and cerebrovascular diseases are currently the leading causes of mortality and disability worldwide. Both the heart and brain display similar vascular anatomy, with large conduit arteries running on the surface of the organ providing tissue perfusion through an intricate network of penetrating small vessels. Both organs rely on fine tuning of local blood flow to match metabolic demand. Blood flow regulation requires adequate functioning of the microcirculation in both organs, with loss of microvascular function, termed small vessel disease (SVD) underlying different potential clinical manifestations. SVD in the heart, known as coronary microvascular dysfunction, can cause chronic or acute myocardial ischemia and may lead to development of heart failure. In the brain, cerebral SVD can cause an acute stroke syndrome known as lacunar stroke or more subtle pathological alterations of the brain parenchyma, which may eventually lead to neurological deficits or cognitive decline in the long term. Coronary microcirculation cannot be visualized in vivo in humans, and functional information can be deduced by measuring the coronary flow reserve. The diagnosis of cerebral SVD is largely based on brain magnetic resonance imaging, with white matter hyperintensities, microbleeds, and brain atrophy reflecting key structural changes. There is evidence that such structural changes reflect underlying cerebral SVD. Here, we review interactions between SVD and cardiovascular risk factors, and we discuss the evidence linking cerebral SVD with large vessel atheroma, atrial fibrillation, heart failure, and heart valve disease.

Atrial Fibrillation and Cognitive Impairment: An Associated Burden or Burden by Association?

Growing evidence suggests that atrial fibrillation (AF), in addition to its thromboembolic risk, is a risk factor for cognitive impairment (CI) via several pathways and mechanisms, further contributing to morbidity/mortality. Prior stroke is a contributor to CI, but AF is also associated with CI independently from prior stroke. Silent brain infarctions, microemboli and microbleeds, brain atrophy, cerebral hypoperfusion from widely fluctuating ventricular rates, altered hemostatic function, vascular oxidative stress, and inflammation may all exacerbate CI, particularly in patients with persistent/permanent rather than paroxysmal AF and with increased duration/burden of the arrhythmia. Brain magnetic resonance imaging is an important screening tool in eliciting and monitoring vascular and nonvascular lesions contributing to CI. Evidence is also emerging about the role of genetics in CI development. Anticoagulation and rhythm/rate control strategies may protect against CI preventing or slowing its progression or conversion to dementia, particularly at the early stages when CI may still be a treatable condition. Importantly, AF and CI share many common risk factors. Thus, screening for these 2 conditions and searching for and managing modifiable risk factors and potentially reversible causes for both AF and CI remains an important step toward prevention or amelioration of the impact incurred by these 2 conditions.

The ASCOD Phenotyping of Embolic Strokes of Undetermined Source

BACKGROUND AND PURPOSE

Various pathogenesis are presumed to be involved in the etiology of embolic stroke of undetermined source (ESUS), which has a high recurrence rate, and much remains unknown about the clinical subtype of recurrent stroke. The purpose of this study was to clarify the pathogenesis of ESUS using the ASCOD classification for ESUS patients and to examine the factors involved in the recurrence of ischemic stroke.

METHODS

The subjects of this study were 236 of these patients who fulfilled the criteria for ESUS. The rate of stroke recurrent, subtype of recurrent ischemic stroke, and new-onset atrial fibrillation (AF) in these patients were surveyed retrospectively, and each patient was graded for the A, S, and C categories of the ASCOD classification.

RESULTS

Ischemic stroke recurred in 32 patients during the follow-up period (7 days to 12.9 years [median 54.3 months]), and new-onset AF was seen in 44 (18.6%) patients. The most subtype of recurrent ischemic stroke was ESUS again (19 patients). Multivariate analysis with a Cox proportional hazards model, the S score (hazard ratio 5.21; 95% confidence interval (CI) 2.38-11.42; P < .001) and the number of A, S, C categories (hazard ratio 1.90; 95% CI 1.14-3.10; P = .013) were factors significantly related to recurrent ischemic stroke.

CONCLUSIONS

Assessment of comorbid conditions in ESUS patients based on the ASCOD classification may be useful in predicting the likelihood of recurrence of ischemic stroke.

Prevalence of Systemic Atherosclerosis Burdens and Overlapping Stroke Etiologies and Their Associations With Long-term Vascular Prognosis in Stroke With Intracranial Atherosclerotic Disease

Importance

Patients who have experienced stroke with intracranial atherosclerotic disease (ICAD) may also have concomitant atherosclerosis in different arterial beds and other possible causes for ischemic stroke. However, little is known about the frequency and prognostic effect of such overlapping diseases.

Objectives

To describe the prevalence of systemic atherosclerotic burdens and overlapping stroke etiologies and their contributions to long-term prognoses among patients who have experienced stroke with ICAD.

Design, Setting, and Participants

The Asymptomatic Myocardial Ischemia in Stroke and Atherosclerotic Disease study is a single-center prospective study in which 405 patients with acute ischemic stroke within 10 days of onset were consecutively enrolled between June 2005 and December 2008 and followed up for 4 years. After excluding 2 patients because of incomplete investigations, 403 were included in this analysis.

Main Outcomes and Measures

Significant ICAD was defined as having 50% or greater stenosis/occlusion by contrast-enhanced/time-of-flight magnetic resonance angiography, computed tomography angiography, and/or transcranial Doppler ultrasonography. Systemic vascular investigations on atherosclerotic disease were performed with ultrasonography in carotid arteries, aorta and femoral arteries, and by angiography in coronary arteries. Coexistent stroke etiologies were assessed using the atherosclerosis, small-vessel disease, cardiac pathology, other cause, and dissection (ASCOD) grading system. We estimated the 4-year risk of major adverse cardiovascular events (MACE), including vascular death, nonfatal cardiac events, nonfatal stroke, and major peripheral arterial events.

Results

Of 403 participants, 298 (74%) were men and the mean (SD) age was 62.6 (13.1) years. Significant ICAD was found in 146 (36.2%). Patients with significant ICAD more often had aortic arch (70 [60.9%] vs 99 [49.0%]; P = .04) and coronary artery (103 [76.9%] vs 153 [63.2%]; P = .007) atherosclerosis than those without. Among patients with ICAD, concurrent stenosis in the extracranial carotid artery (24 [23.4%] vs 3 [9.0%]; P = .08; adjusted hazard ratio[aHR] = 2.12) and the coronary artery (19 [29.9%] vs 8 [12.8%]; P = .01; aHR = 1.90) increased the MACE risk. Furthermore, patients with ICAD who also had any cardiac pathology (ASCOD grade C1-3) were at a higher MACE risk than others (grade C0) (20 [28.2%] vs 7 [11.4%]; P = .01; aHR = 2.24). By contrast, patients with ICAD with any form of small vessel disease (grade S1-3) had a lower MACE risk than those without (grade S0) (20 [17.3%] vs 6 [34.6%]; P = .05; aHR = 0.23).

Conclusions and Relevance

Patients with ICAD often have coexisting systemic atherosclerosis and multiple potential stroke mechanisms that affect their prognosis, suggesting that extensive evaluations of overlapping diseases may allow better risk stratification.

Cognitive dysfunction in atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia in adults, and its incidence and prevalence increase with age. The risk of cognitive impairment and dementia also increases with age, and both AF and cognitive impairment or dementia share important risk factors. In meta-analyses of published studies, AF is associated with a 2.4-fold and 1.4-fold increase in the risk of dementia in patients with or without a history of stroke, respectively. This association is independent of shared risk factors such as hypertension and diabetes mellitus. Neuroimaging has illustrated several potential mechanisms of cognitive decline in patients with AF. AF is associated with increased prevalence of silent cerebral infarcts, and more recent data also suggest an increased prevalence of cerebral microbleeds with AF. AF is also associated with a pro-inflammatory state, and the relationship between AF-induced systemic inflammation and dementia remains to be investigated. Preliminary reports indicate that anticoagulation medication including warfarin can reduce the risk of cognitive impairment in patients with AF. Catheter ablation, increasingly used to maintain sinus rhythm in patients with AF, is associated with the formation of new silent cerebral lesions. The majority of these lesions are not detectable after 1 year, and insufficient data are available to evaluate their effect on cognition. Large prospective studies are urgently needed to confirm the association between AF and dementia, to elucidate the associated mechanisms, and to investigate the effect of anticoagulation and rhythm control on cognition.

A Non-linear Association Between Total Small Vessel Disease Score and Hemorrhagic Transformation After Ischemic Stroke With Atrial Fibrillation and/or Rheumatic Heart Disease

Background: Previous studies have investigated the association between a single marker of cerebral small vessel disease (SVD) and hemorrhagic transformation (HT). However, the effect of the total SVD burden on HT has not been evaluated yet. We aimed to investigate the association between the total SVD score and HT in ischemic stroke patients with atrial fibrillation (AF) and/or rheumatic heart disease (RHD). Methods: Ischemic stroke patients with AF and/or RHD admitted within 7 days after onset were enrolled at two hospitals in China. The total SVD score was based on the presence of lacunes, extensive white matter hyperintensities, cerebral microbleeds, and moderate to severe enlarged perivascular spaces in the basal ganglia. One point was awarded for the presence of each marker, with the total SVD score ranging from 0 to 4 points. HT was assessed based on follow-up imaging scans during hospitalization and was classified according to the radiographic appearance and associated neurological deterioration. Results: Of 207 enrolled patients (mean age, 67.79 years; 58.9% female), 89 (43.0%) developed HT. The distribution of the total SVD score was significantly different between patients with and without HT in the univariate analysis (p = 0.04). After adjustment for confounders, a SVD score of 1 was independently associated with an increased risk of HT [odds ratio (OR), 3.23; 95% confidence interval (CI), 1.48-7.04; p = 0.003], while a SVD score ≥2 was inversely related to the occurrence of HT (OR, 0.41; 95% CI, 0.19-0.91; p = 0.03). These independent associations remained significant in the subgroups of hemorrhagic infarction and asymptomatic HT (all p < 0.05). Conclusions: In our study, the relationship between the total SVD score and HT was not linear, since the presence of only one marker of SVD was associated with an increased risk of HT, while the presence of two or more markers of SVD was a potential protective factor for HT. These results indicate the need to take the total SVD score into account, not only a single SVD marker, when assessing the risk of HT. Further studies with larger samples are required to validate these findings.

Correlation between Fibrinogen and White Matter Hyperintensities among Nondiabetic Individuals with Noncardiogenic Ischemic Stroke

OBJECTIVE

The aim of the present study is to confirm the correlation between fibrinogen and the severity of cerebral white matter hyperintensities (WMHs) among nondiabetic patients with noncardiogenic acute ischemic stroke.

PATIENTS AND METHODS

A cross-sectional study of 170 consecutive patients with noncardiogenic acute ischemic stroke who underwent magnetic resonance imaging and vascular imaging was conducted. WMHs were classified into periventricular hyperintensity (PVH) and deep and subcortical WMH (DSWMH) using Fazekas rating scale. After adjustment for fibrinogen and other vascular risk factors, we determined which factors were independent of WMHs.

RESULTS

After adjustment for the vascular risk factors, prior ischemic stroke (odds ratio [OR] 4.153, 95% confidence interval [CI] 1.077-16.020, P = .039), fibrinogen level (OR 2.114, 95% CI 1.034-4.322, P = .040), and glycosylated hemoglobin A1c (OR .633, 95% CI .423-.947, P = .026) were independently and positively associated with PVH (P < .05); prior ischemic stroke (OR 2.841, 95% CI 1.469-5.493, P = .002), lipoprotein(a) (OR 1.002, 95% CI 1.000-1.005, P = .047), and fibrinogen levels (OR 1.788, 95% CI 1.170-2.732, P = .007) were independently and positively associated with DSWMH (P < .05).

CONCLUSIONS

Our study demonstrated that prior ischemic stroke and higher fibrinogen are associated with WMHs, regardless of PVH and DSWMH, in nondiabetic patients with noncardiogenic acute ischemic stroke. In addition, lipoprotein(a) might be an independent predictor of DSWMH in patients with noncardiogenic acute ischemic stroke.

Magnetic Resonance Imaging White Matter Hyperintensity as a Predictor of Stroke Recurrence in Patients with Embolic Stroke of Undetermined Source

BACKGROUND AND PURPOSE

This study aimed to investigate factors associated with stroke recurrence and new-onset atrial fibrillation (AF) in patients with embolic stroke of undetermined source (ESUS).

METHODS

Between January 2005 and March 2012, a total of 1514 consecutive patients were admitted to our hospital with a diagnosis of acute ischemic stroke within 7 days after onset. Of these, 236 patients met the diagnostic criteria for ESUS. A retrospective analysis was performed of the following characteristics of these ESUS patients: medical history, comorbidities, and magnetic resonance imaging (MRI) findings including the deep and subcortical white matter hyperintensity (DSWMH) grade, drugs used for preventing recurrence, and clinical information such as NIH Stroke Scale scores on admission and outcomes evaluated by modified Rankin scale. The rate of recurrence after discharge and the frequency of new-onset AF were also determined.

RESULTS

There were 236 ESUS patients (141 men, mean age 70.2 ± 12.1 years). During the follow-up period, ranging from 7 days to 12.9 years (median 54.3 months), 32 (13.6%) and 44 (18.6%) of these patients had a recurrent ischemic stroke and new-onset AF, respectively. The most prevalent subtype of recurrent ischemic stroke was ESUS itself; this type of stroke occurred in 19 (59.3%) patients. AF was observed at stroke recurrence, but only 2 patients were diagnosed with cardioembolism. Multivariate analysis with a Cox proportional hazard model demonstrated that DSWMH grade greater than or equal to 3 was significantly associated with both recurrent ischemic stroke (hazard ratio 3.66, 95% confidence interval 1.69-7.92, P = .001) and new-onset AF (2.00, 1.03-3.90, .04).

CONCLUSIONS

MRI classification of white matter hyperintensity could be effectively used as a predictor for recurrent ischemic stroke and new-onset AF in patients with ESUS.

Atrial Fibrillation, Cognitive Decline, and Dementia: an Epidemiologic Review

PURPOSE OF REVIEW

Atrial fibrillation (AF) and dementia are both prevalent diseases in aging societies, which exert a great economic burden worldwide. Although a handful of epidemiologic studies have indicated that AF is independently associated with faster cognitive decline and a higher risk of dementia, there is still a lack of comprehensive understanding of the observed association. In this review, we summarize evidence from major epidemiologic studies concerning AF-related cognitive decline and dementia, the potential mechanisms underlying their association, and the cognitive benefits of treatment options.

RECENT FINDINGS

A large majority of population-based longitudinal studies have consistently shown an independent association of AF with cognitive decline and dementia with varying effect sizes, depending on the age of the study population and the presence of clinical stroke. The underlying pathways linking AF to cognitive phenotypes may involve systemic inflammation, cerebral hypoperfusion, and cerebral small vessel disease and microemboli. However, current evidence is insufficient to support the potential benefits of AF treatment in reducing risk of cognitive decline and dementia.

SUMMARY

Current epidemiologic research suggests that AF contributes to cognitive decline and dementia, independent of a history of stroke. Further work is warranted to elucidate the potential mechanisms underlying this association, and more well-designed studies are needed to explore the possible cognitive benefits of different therapeutic options in patients with AF.

Cardiovascular disease and brain health: Focus on white matter hyperintensities

Diseases affecting the brain contribute to a substantial proportion of morbidity and mortality in the general population. Conditions such as stroke, dementia and cognitive impairment have a prominent impact on global public health. Despite the heterogeneous clinical manifestations of these conditions and their diverse prognostic implications, current evidence supports a role for cardiovascular disease as a common pathophysiological ground. Brain white matter hyperintensities (WMH) are patchy white matter signal hyperintensity on T2-weighted magnetic resonance imaging sequences commonly found in elderly individuals. WMH appear to have a vascular pathogenesis and have been shown to confer an increased risk of stroke and cognitive decline. Indeed, they were proposed as a marker for central nervous system frailty. Cardiovascular diseases seem to play a key role in the etiology of WMH. Carotid atherosclerosis and atrial fibrillation were shown to be associated with higher WMH burden, while adequate blood pressure control has been reported reducing WMH progression. Aim of the present work is to review the available evidence linking WMH to cardiovascular disease, highlighting the complex interplay between cerebral and cardiovascular health.

Association between Fibrinogen and Leukoaraiosis in Patients with Ischemic Stroke and Atrial Fibrillation

BACKGROUND

Leukoaraiosis (LA), a surrogate of cerebral small-vessel diseases (CSVD), has been increasingly recognized because of its high prevalence and strong prognostic value in stroke. But the mechanism of LA is incompletely clarified. Fibrinogen is a crucial role in coagulation cascade and inflammation. There are inconsistent reports on the association of fibrinogen with LA in the general population. We aimed to investigate the association between fibrinogen and LA in patients with stroke and atrial fibrillation (AF), which was not ever reported before.

METHODS

Patients with ischemic stroke and AF were prospectively and consecutively recruited. Clinico-demographic data and fibrinogen levels were collected within 48 hours from stroke onsets and analyzed according to the presence and distribution of LA (periventricular hyperintensity [PVH] and deep white matter hyperintensity).

RESULTS

Of 186 patients (34.4% male; mean age, 68.76 ± 12.76 years) enrolled, 134 patients (72.0%) presented with LA. Elevated fibrinogen levels were associated with higher presence of LA (P = .005) and PVH (P = .002). After adjustment for the confounders, the fibrinogen levels were independently correlated with LA and PVH (all P <.05). Patients with elevated fibrinogen levels (≥3.5 g/L) were more likely to present with LA and PVH, with the odds ratios of 14.037 (95% confidence interval [CI] 2.588-76.131) and 12.567 (95% CI 2.572-61.395), respectively.

CONCLUSION

This study found that fibrinogen was independently and positively associated with LA and PVH in patients with stroke and AF. These results provide further evidence for the key role of fibrinogen in LA, even the total CSVD burden.

Structural MRI markers of brain aging early after ischemic stroke

Objective:

To examine associations between ischemic stroke, vascular risk factors, and MRI markers of brain aging.

Methods:

Eighty-one patients (mean age 67.5 ± 13.1 years, 31 left-sided, 61 men) with confirmed first-ever (n = 66) or recurrent (n = 15) ischemic stroke underwent 3T MRI scanning within 6 weeks of symptom onset (mean 26 ± 9 days). Age-matched controls (n = 40) completed identical testing. Multivariate regression analyses examined associations between group membership and MRI markers of brain aging (cortical thickness, total brain volume, white matter hyperintensity [WMH] volume, hippocampal volume), normalized against intracranial volume, and the effects of vascular risk factors on these relationships.

Results:

First-ever stroke was associated with smaller hippocampal volume (p = 0.025) and greater WMH volume (p = 0.004) relative to controls. Recurrent stroke was in turn associated with smaller hippocampal volume relative to both first-ever stroke (p = 0.017) and controls (p = 0.001). These associations remained significant after adjustment for age, sex, education, and, in stroke patients, infarct volume. Total brain volume was not significantly smaller in first-ever stroke patients than in controls (p = 0.056), but the association became significant after further adjustment for atrial fibrillation (p = 0.036). Cortical thickness and brain volumes did not differ as a function of stroke type, infarct volume, or etiology.

Conclusions:

Brain structure is likely to be compromised before ischemic stroke by vascular risk factors. Smaller hippocampal and total brain volumes and increased WMH load represent proxies for underlying vascular brain injury.

Apixaban for treatment of embolic stroke of undetermined source (ATTICUS randomized trial): Rationale and study design

Rationale

Optimal secondary prevention of embolic stroke of undetermined source is not established. The current standard in these patients is acetylsalicylic acid, despite high prevalence of yet undetected paroxysmal atrial fibrillation.

Aim

The ATTICUS randomized trial is designed to determine whether the factor Xa inhibitor apixaban administered within 7 days after embolic stroke of undetermined source, is superior to acetylsalicylic acid for prevention of new ischemic lesions documented by brain magnetic resonance imaging within 12 months after index stroke.

Design

Prospective, randomized, blinded, parallel-group, open-label, German multicenter phase III trial in approximately 500 patients with embolic stroke of undetermined source. A key inclusion criterion is the presence or the planned implantation of an insertable cardiac monitor. Patients are 1:1 randomized to apixaban or acetylsalicylic acid and treated for a 12-month period. It is an event-driven trial aiming for core-lab adjudicated primary outcome events.

Study outcomes

The primary outcome is the occurrence of at least one new ischemic lesion identified by axial T2-weighted FLAIR magnetic resonance imaging and/or axial DWI magnetic resonance imaging at 12 months when compared with the baseline magnetic resonance imaging. Key secondary outcomes are the combination of recurrent ischemic strokes, hemorrhagic strokes, systemic embolism; combination of MACE including recurrent stroke, myocardial infarction, and cardiovascular death and combination of major and clinically relevant non-major bleeding defined according to ISTH, and change of cognitive function and quality of life (EQ-5D, Stroke Impact Scale).

Discussion

Embolic stroke of undetermined source is caused by embolic disease and associated with a high risk of recurrent ischemic strokes and clinically silent cerebral ischemic lesions. ATTICUS will investigate the impact of atrial fibrillation detected by insertable cardiac monitor and the effects of early anticoagulation with apixaban compared with antiplatelet therapy with acetylsalicylic acid on the incidence of new ischemic lesion after embolic stroke of undetermined source.

Silent brain infarcts in high blood pressure patients with cardiac implantable electronic devices: unmasking silent atrial fibrillation

BACKGROUND

Hypertensive patients present a higher risk for developing atrial fibrillation and its complications. Cardiac implantable electronic devices (CIEDs) have shown reliable atrial fibrillation detection as atrial high-rate episodes (AHREs). The presence of AHRE more than 5 min has been related to increased risk of stroke, but a high proportion of ischemic brain lesions (IBLs) could be subclinical and thromboembolic risk underestimated.

METHODS

We included hypertensive patients with CIED and we analyzed the incidence of AHRE and the presence of IBL on computed tomography (CT) scan.

RESULTS

One hundred and twenty-three patients (57% men) aged 77 ± 8 years were evaluated during a mean follow-up of 15 ± 9 months. AHREs were documented in 46 patients (37%). Cranial CT scan showed silent IBL in 34 patients (27%). Univariate analysis showed that age, CHADS2 and CHADS2VA2Sc scores, history of prior stroke/ transient ischemic attack and the presence of AHRE were significantly related to higher risk for IBL on CT scan (P < 0.05). Multivariate analysis showed that the presence of AHRE more than 5 min [odds ratio 3.05 (1.19-7.81; P < 0.05)] was an independent predictor of IBL.

CONCLUSION

Silent atrial fibrillation detected by CIED as AHRE is really prevalent in hypertensive patients. AHREs were independently associated with a higher incidence of silent IBL on CT scan.

Association between atrial fibrillation and volumetric magnetic resonance imaging brain measures: Framingham Offspring Study

BACKGROUND

The increased risk of stroke and cognitive impairment associated with atrial fibrillation (AF) is well documented. However, there is a paucity of research investigating the relations between AF and brain morphology.

OBJECTIVE

The purpose of this study was to investigate the association between AF and brain volume measures on magnetic resonance imaging (MRI).

METHODS

The study sample included stroke- and dementia-free participants who attended the Framingham Heart Study offspring cohort 7th examination cycle (1999-2005) and underwent contemporaneous MRI. We examined the association between prevalent AF and brain volume measures (total cerebral volume, frontal lobe volume, temporal lobe volume, temporal horn volume, hippocampal volume, and white matter hyperintensity volume) with linear regression. We first adjusted models for age and sex, and then for vascular risk factors and APOE4.

RESULTS

We studied 2144 individuals (mean age 61.8 ± 9.3 years; 54% women); 73 participants (3.4%) had prevalent AF at the time of MRI. In age- and sex-adjusted models, AF was inversely associated with total cerebral brain volume, frontal brain volume, and temporal brain volume. After further adjustment for vascular risk factors and APOE4, AF remained associated with frontal brain volume.

CONCLUSION

After accounting for vascular risk factor burden, prevalent AF was associated with lobar indexes of vascular brain aging but not with expected white matter changes.

Effect of apixaban on brain infarction and microbleeds: AVERROES-MRI assessment study

BACKGROUND

Clinical and subclinical (covert) stroke is a cause of cognitive loss and functional impairment. In the AVERROES trial, we performed serial brain magnetic resonance imaging (MRI) scans in a subgroup to explore the effect of apixaban, compared with aspirin, on clinical and covert brain infarction and on microbleeds in patients with atrial fibrillation.

METHODS

We performed brain MRI (T1, T2, fluid-attenuated inversion recovery, and T2* gradient echo sequences) in 1,180 at baseline and in 931 participants at follow-up. Mean interval from baseline to follow-up MRI scans was 1.0 year. The primary outcome was a composite of clinical ischemic stroke and covert embolic pattern infarction (defined as infarction >1.5 cm, cortical-based infarction, or new multiterritory infarction). Secondary outcomes included new MRI-detected brain infarcts and microbleeds and change in white matter hyperintensities.

RESULTS

Baseline MRI scans revealed brain infarct(s) in 26.2% and microbleed(s) in 10.5%. The rate of the primary outcomes was 2.0% in the apixaban group and 3.3% in the aspirin group (hazard ratio [HR] 0.55; 0.27-1.14) from baseline to follow-up MRI scan (mean duration of follow-up: 1 year). In those who completed baseline and follow-up MRI scans, the rate of new infarction detected on MRI was 2.5% in the apixaban group and 2.2% in the aspirin group (HR 1.09; 0.47-2.52), but new infarcts were smaller in the apixaban group (P = .03). There was no difference in proportion with new microbleeds on follow-up MRI (HR 0.92; 0.53-1.60) between treatment groups.

CONCLUSIONS

Apixaban treatment was associated with a nonsignificant trend toward reduction in the composite of clinical ischemic stroke and covert embolic-pattern infarction and did not increase the number of microbleeds in patients with atrial fibrillation compared with aspirin.

Atrial fibrillation and silent stroke: links, risks, and challenges

Atrial fibrillation (AF) is the most common cardiac arrhythmia, with a projected number of 1 million affected subjects in Germany. Changes in age structure of the Western population allow for the assumption that the number of concerned people is going to be doubled, maybe tripled, by the year 2050. Large epidemiological investigations showed that AF leads to a significant increase in mortality and morbidity. Approximately one-third of all strokes are caused by AF and, due to thromboembolic cause, these strokes are often more severe than those caused by other etiologies. Silent brain infarction is defined as the presence of cerebral infarction in the absence of corresponding clinical symptomatology. Progress in imaging technology simplifies diagnostic procedures of these lesions and leads to a large amount of diagnosed lesions, but there is still no final conclusion about frequency, risk factors, and clinical relevance of these infarctions. The prevalence of silent strokes in patients with AF is higher compared to patients without AF, and several studies reported high incidence rates of silent strokes after AF ablation procedures. While treatment strategies to prevent clinically apparent strokes in patients with AF are well investigated, the role of anticoagulatory treatment for prevention of silent infarctions is unclear. This paper summarizes developments in diagnosis of silent brain infarction and its context to AF.

Incident Atrial Fibrillation and Disability-Free Survival in the Cardiovascular Health Study

OBJECTIVES

To assess the associations between incident atrial fibrillation (AF) and disability-free survival and risk of disability.

DESIGN

Prospective cohort study.

SETTING

Cardiovascular Health Study.

PARTICIPANTS

Individuals aged 65 and older and enrolled in fee-for-service Medicare followed between 1991 and 2009 (MN = 4,046). Individuals with prevalent AF, activity of daily living (ADL) disability, or a history of stroke or heart failure at baseline were excluded.

MEASUREMENTS

Incident AF was identified according to annual study electrocardiogram, hospital discharge diagnosis, or Medicare claims. Disability-free survival was defined as survival free of ADL disability (any difficulty or inability in bathing, dressing, eating, using the toilet, walking around the home, or getting out of a bed or chair). ADLs were assessed at annual study visits or in a telephone interview. Association between incident AF and disability-free survival or risk of disability was estimated using Cox proportional hazards models.

RESULTS

Over an average of 7.0 years of follow-up, 660 individuals (16.3%) developed incident AF, and 3,112 (77%) became disabled or died. Incident AF was associated with shorter disability-free survival (hazard ratio (HR) for death or ADL disability = 1.71, 95% confidence interval (CI) = 1.55-1.90) and a higher risk of ADL disability (HR = 1.36, 95% CI = 1.18-1.58) than in individuals with no history of AF. This association persisted after adjustment for interim stroke and heart failure.

CONCLUSION

These results suggest that AF is a risk factor for shorter functional longevity in older adults, independent of other risk factors and comorbid conditions.

Almanac 2015: atrial fibrillation research in Heart

Atrial fibrillation continues to attract interest in the cardiovascular community and in Heart. Over 60 original research and review papers published in Heart in 2014–2015 cover various aspects of atrial fibrillation, from associated conditions and precipitating factors to new approaches to management. Here, we provide an overview of articles on atrial fibrillation published in Heart in 2014–2015, highlighting new developments, emerging concepts and novel approaches to treatment.

Predictors of silent brain infarction on magnetic resonance imaging in patients with nonvalvular atrial fibrillation: A transesophageal echocardiographic study

BACKGROUND

Silent brain infarction (SBI) is often found in patients with atrial fibrillation (AF) and may be related to cognitive decline. We investigated the predictors of SBI on brain magnetic resonance imaging (MRI) using transesophageal echocardiography (TEE) in patients with nonvalvular AF.

METHODS

The study population consisted of 103 neurologically asymptomatic patients with nonvalvular AF who underwent TEE before transcatheter AF ablation (76 men; mean age 63 ± 10 years). Left atrial (LA) abnormalities such as LA thrombus, spontaneous echo contrast, or abnormal LA appendage emptying velocity (<20 cm/s) and complex plaques in the aortic arch defined as large plaques ≥4 mm thickness, ulcerated plaques, or mobile plaques were evaluated by TEE. All patients were screened for SBI by brain MRI.

RESULTS

Of 103 patients, 31 (30%) showed SBI on brain MRI. Most lesions were multiple (61%) and small (<15 mm) in diameter (84%). Patients with SBI had a higher prevalence of LA abnormalities (45% vs 14%; P < .001) and complex arch plaques (45% vs 7%; P < .001) compared with those without SBI. In a multivariate logistic regression analysis including age and CHADS2 score ≥2, LA abnormalities (odds ratio 4.13; 95% CI 1.34-12.72; P = .014) and complex arch plaques (odds ratio 4.82; 95% CI 1.23-18.92; P = .024) were independent predictors of SBI.

CONCLUSIONS

Left atrial abnormalities and complex arch plaques detected by TEE were closely associated with the presence of SBI on brain MRI, suggesting that microembolization of small thrombi derived from the fibrillating LA or advanced aortic atherosclerotic lesions may be important causes of SBI in patients with nonvalvular AF.

Brain and kidney, victims of atrial microembolism in elderly hospitalized patients? Data from the REPOSI study

BACKGROUND

It is well known that atrial fibrillation (AF) and chronic kidney disease (CKD) are associated with a higher risk of stroke, and new evidence links AF to cognitive impairment, independently from an overt stroke (CI). Our aim was to investigate, assuming an underlying role of atrial microembolism, the impact of CI and CKD in elderly hospitalized patients with AF.

METHODS

We retrospectively analyzed the data collected on elderly patients in 66 Italian hospitals, in the frame of the REPOSI project. We analyzed the clinical characteristics of patients with AF and different degrees of CI. Multivariate logistic analysis was used to explore the relationship between variables and mortality.

RESULTS

Among the 1384 patients enrolled, 321 had AF. Patients with AF were older, had worse CI and disability and higher rates of stroke, hypertension, heart failure, and CKD, and less than 50% were on anticoagulant therapy. Among patients with AF, those with worse CI and those with lower estimated glomerular filtration rate (eGFR) had a higher mortality risk (odds ratio 1.13, p=0.006). Higher disability levels, older age, higher systolic blood pressure, and higher eGFR were related to lower probability of oral anticoagulant prescription. Lower mortality rates were found in patients on oral anticoagulant therapy.

CONCLUSIONS

Elderly hospitalized patients with AF are more likely affected by CI and CKD, two conditions that expose them to a higher mortality risk. Oral anticoagulant therapy, still underused and not optimally enforced, may afford protection from thromboembolic episodes that probably concur to the high mortality.