Stroke Prevention in Atrial Fibrillation: Our Current Failures and Required Research

Nonvalvular atrial fibrillation is a common rhythm disorder of middle-aged to older adults that can cause ischemic strokes and systemic embolism. Lifelong use of oral anticoagulants reduces the risk of these ischemic events but increases the risk of major and clinically relevant hemorrhages. These medications also require strict compliance for efficacy, and they have nontrivial failure rates in higher-risk patients. Left atrial appendage closure is a nonpharmacological method to prevent ischemic strokes in atrial fibrillation without the need for lifelong anticoagulant use, but this procedure has the potential for complications and residual embolic events. This workshop of the Roundtable of Academia and Industry for Stroke Prevention discussed future research needed to further decrease the ischemic and hemorrhagic risks among patients with atrial fibrillation. A direct thrombin inhibitor, factor Xa inhibitors, and left atrial appendage closure are FDA-approved approaches whereas factor XIa inhibitors are currently being studied in phase 3 randomized controlled trials for stroke prevention. The benefits, risks, and shortcomings of these treatments and future research required in different high-risk patient populations are reviewed in this consensus statement.

Mechanistic Implications of Cortical Superficial Siderosis in Patients With Mixed Location Intracerebral Hemorrhage and Cerebral Microbleeds

BACKGROUND AND OBJECTIVES

Hypertensive cerebral small vessel disease (HTN-cSVD) is the predominant microangiopathy in patients with a combination of lobar and deep cerebral microbleeds (CMBs) and intracerebral hemorrhage (mixed ICH). We tested the hypothesis that cerebral amyloid angiopathy (CAA) is also a contributing microangiopathy in patients with mixed ICH with cortical superficial siderosis (cSS), a marker strongly associated with CAA.

METHODS

Brain MRIs from a prospective database of consecutive patients with nontraumatic ICH admitted to a referral center were reviewed for the presence of CMBs, cSS, and nonhemorrhagic CAA markers (lobar lacunes, centrum semiovale enlarged perivascular spaces [CSO-EPVS], and multispot white matter hyperintensity [WMH] pattern). The frequencies of CAA markers and left ventricular hypertrophy (LVH), a marker for hypertensive end-organ damage, were compared between patients with mixed ICH with cSS (mixed ICH/cSS[+]) and without cSS (mixed ICH/cSS[-]) in univariate and multivariable models.

RESULTS

Of 1,791 patients with ICH, 40 had mixed ICH/cSS(+) and 256 had mixed ICH/cSS(-). LVH was less common in patients with mixed ICH/cSS(+) compared with those with mixed ICH/cSS(-) (34% vs 59%, p = 0.01). The frequencies of CAA imaging markers, namely multispot pattern (18% vs 4%, p < 0.01) and severe CSO-EPVS (33% vs 11%, p < 0.01), were higher in patients with mixed ICH/cSS(+) compared with those with mixed ICH/cSS(-). In a logistic regression model, older age (adjusted odds ratio [aOR] 1.04 per year, 95% CI 1.00-1.07, p = 0.04), lack of LVH (aOR 0.41, 95% CI 0.19-0.89, p = 0.02), multispot WMH pattern (aOR 5.25, 95% CI 1.63-16.94, p = 0.01), and severe CSO-EPVS (aOR 4.24, 95% CI 1.78-10.13, p < 0.01) were independently associated with mixed ICH/cSS(+) after further adjustment for hypertension and coronary artery disease. Among ICH survivors, the adjusted hazard ratio of ICH recurrence in patients with mixed ICH/cSS(+) was 4.65 (95% CI 1.38-11.38, p < 0.01) compared with that in patients with mixed ICH/cSS(-).

DISCUSSION

The underlying microangiopathy of mixed ICH/cSS(+) likely includes both HTN-cSVD and CAA, whereas mixed ICH/cSS(-) is likely driven by HTN-cSVD. These imaging-based classifications can be important to stratify ICH risk but warrant confirmation in studies incorporating advanced imaging/pathology.

Peak width of skeletonized mean diffusivity and cognitive performance in cerebral amyloid angiopathy

Background

Cerebral Amyloid Angiopathy (CAA) is a cerebral small vessel disease that can lead to microstructural disruption of white matter (WM), which can be measured by the Peak Width of Skeletonized Mean Diffusivity (PSMD). We hypothesized that PSMD measures would be increased in patients with CAA compared to healthy controls (HC), and increased PSMD is associated with lower cognitive scores in patients with CAA.

Methods

Eighty-one probable CAA patients without cognitive impairment who were diagnosed with Boston criteria and 23 HCs were included. All subjects underwent an advanced brain MRI with high-resolution diffusion-weighted imaging (DWI). PSMD scores were quantified from a probabilistic skeleton of the WM tracts in the mean diffusivity (MD) image using a combination of fractional anisotropy (FA) and the FSL Tract-Based Spatial Statistics (TBSS) algorithm (www.psmd-marker.com). Within CAA cohort, standardized z-scores of processing speed, executive functioning and memory were obtained.

Results

The mean of age and sex were similar between CAA patients (69.6 ± 7.3, 59.3% male) and HCs (70.6 ± 8.5, 56.5% male) (p = 0.581 and p = 0.814). PSMD was higher in the CAA group [(4.13 ± 0.94) × 10-4 mm2/s] compared to HCs [(3.28 ± 0.51) × 10-4 mm2/s] (p < 0.001). In a linear regression model corrected for relevant variables, diagnosis of CAA was independently associated with increased PSMD compared to HCs (ß = 0.45, 95% CI 0.13-0.76, p = 0.006). Within CAA cohort, higher PSMD was associated with lower scores in processing speed (p < 0.001), executive functioning (p = 0.004), and memory (0.047). Finally, PSMD outperformed all other MRI markers of CAA by explaining most of the variance in models predicting lower scores in each cognitive domain.

Discussion

Peak Width of Skeletonized Mean Diffusivity is increased in CAA, and it is associated with worse cognitive scores supporting the view that disruption of white matter has a significant role in cognitive impairment in CAA. As a robust marker, PSMD can be used in clinical trials or practice.

Abstract TMP76: Left Atrial Appendage Closure In Atrial Fibrillation Patients At High Intracranial Hemorrhage Risk

Background: Lifelong oral anticoagulant (OAC) use is associated with higher intracranial hemorrhage (ICH) risk in nonvalvular atrial fibrillation (NVAF) patients. We aimed to assess the long-term outcomes of left atrial appendage closure (LAAC) in NVAF patients at high baseline ICH risk, as LAAC was FDA-approved for NVAF patients who have a reasonable rationale to seek a nonpharmacological alternative to lifelong OAC use.

Methods: We collected baseline and follow up data from consecutive NVAF patients who had LAAC because of either past ICH or finding cerebral microbleeds (CMB) on MRI without ICH (CMB-only). The outcome measures were the occurrence of ICH or acute ischemic stroke (AIS) after LAAC.

Results: Out of a total of 644 LAAC performed in a single hospital system between 2015-2022, 142 NVAF patients had LAAC with WATCHMAN because of past ICH or CMB-only. Their mean age was 75.8± 7.6, 41 were female (29%). Mean CHA 2 DS 2 -VASc score was 5.24±1.4. Of the 142 patients, 67 (47.2%) had intraparenchymal hemorrhage (IPH, 52% related to cerebral amyloid angiopathy [CAA]), 19 (13.4%) had non-traumatic subdural hemorrhage (SDH), 36 (25.3%) had traumatic ICH (T-ICH), and 20 (14.08%) were CMB-only (65% with CAA pattern). Eighty-one patients were discharged on OAC (57%) and 133 patients were not taking OAC at 1 year (94%). Over a mean 1.98 years follow up, one patient had recurrent non-traumatic IPH (incidence rate [IR] 0.36 per 100 patient-years), four had traumatic ICH/SDH due to severe falls (IR 1.4%/year), and five had AIS (IR 1.78%/year).

Conclusions: In NVAF patients at high ICH risk, our results show a 74% decrease in AIS risk (actual 1.76%/year vs expected 6.8%/year based on CHA 2 DS 2 -VASc). Despite the very high ICH risk population studied including at least 48 CAA patients, only one patient had a recurrent IPH after LAAC. LAAC should be considered in NVAF patients at high ICH risk and studied in RCTs in this cohort.

Abstract 160: Etiologies Of Intracerebral Hemorrhage In Patients With Atrial Fibrillation On Or Off Oral Anticoagulants: The Neuro-Afib Study

Background: Intracerebral hemorrhage (ICH) is the most feared complication of oral anticoagulants (OAC) used to prevent ischemic strokes (IS) in patients with atrial fibrillation (AF). As different ICH etiologic factors correspond to different ICH risks, we aimed to present the causes of ICH in AF patients who were or were not using OAC, based on data from a multicenter contemporary cohort.

Methods: The Neuro-AFib study is a multicenter effort to elucidate the current causes and consequences of IS and ICH in AF patients. Detailed clinical, laboratory and multimodal imaging data were collected from consecutive patients with AF admitted to 15 US stroke centers with an IS or ICH between 1/2018-12/2019. Etiologic factors of AF patients who were admitted with ICH on OAC (OAC-ICH) and off OAC (nonOAC-ICH) will be compared.

Results: A total of 868 patients presented with ICH and had a diagnosis of AF, either previously known (88%) or diagnosed during admission (12%). 571 patients (66%) were on OAC at the time of their ICH of whom 58% were on direct OAC (DOAC), 40% on warfarin and 2% on heparin. OAC-ICH patients were older than nonOAC-ICH (76.6±10 vs 74.4±13, p=0.006) while sex distribution was the same in both groups (43% female). CHA 2 DS 2 -VASC was higher in OAC-ICH (4.3±1.6 vs 3.9±1.9, p=0.001) but HAS-BLED score was the same in both groups (2.7±1.1). Cerebral amyloid angiopathy (CAA) was diagnosed in 42.5% of the ICH patients based on modified Boston criteria while hypertensive cerebral small vessel disease (HTN-cSVD) in 57.5%. HTN-cSVD was the more common ICH etiology among OAC-ICH (65%) compared to nonOAC-ICH (49%). Among OAC-ICHs, DOAC-related ICHs tended to be more commonly of hypertensive etiology when compared to warfarin-ICH (p=0.09).

Conclusions: Our study is the first to report the etiologic mechanisms of ICH in AF patients on or off OAC. CAA is known to be a major cause of OAC-ICH with exceedingly high recurrence rates. Despite this fact, HTN-cSVD was more common among OAC-ICH (especially DOAC-ICH) patients, supporting the view that the presence/absence of HTN-cSVD risk markers such as deep microbleeds are as important as CAA-markers in determining the optimal stroke prevention method in AF patients (left atrial appendage closure vs lifelong OAC).

Abstract 162: Molecular And Microstructural Alterations In Cerebral Amyloid Angiopathy-related Hemorrhagic Manifestations

Background and Purpose: We aimed to compare the amyloid load and degree of microstructural injury among Cerebral Amyloid Angiopathy (CAA) patients with either higher lobar cerebral microbleed (CMB) counts or higher cortical superficial siderosis (cSS) extent against CAA patients with lower hemorrhagic load.

Methods: The study included 38 cognitively healthy probable CAA patients with lobar intracerebral hemorrhage (ICH) and 38 age, sex-matched healthy controls (HC) who underwent advanced MRI, and Pittsburgh Compound B (PiB) PET scans. Patients were categorized into CMB-Dominant (CMB-D) and cSS-Dominant (cSS-D) based on the number and extent of CMB and cSS using previously identified cutoffs (Figure). The mean global cortical amyloid load was calculated from PiB-PET scans and represented by PiB-DVR. Within the CAA cohort, the Peak Width of Skeletonized Mean Diffusivity (PSMD) was calculated from diffusion MRIs and used as a marker of microstructural integrity.

Results: Patients with CAA had significantly higher PiB-DVR than HCs (1.40±0.24 vs. 1.19±0.22, p<0.001). Both CMB-D and cSS-D CAA patients had significantly higher amyloid and increased (worse) PSMD compared to CAA patients with a non-dominant low hemorrhagic load (Figure). These results did not change in separate regression models corrected for age and sex. PiB-DVR significantly correlated with increased PSMD (r=0.346, p=0.033).

Conclusions: Our findings support the view that vascular amyloid load drives higher CMB counts, more extensive cSS, and microstructural injury in patients with CAA. Furthermore, the correlations among these markers suggest that these MRI-based categorizations (CMB-D and cSS-D patients) can be used for disease staging and further research.

Abstract WP118: Mechanistic Implications Of Cortical Superficial Siderosis In Patients With Mixed Location Intracerebral Hemorrhage And Cerebral Microbleeds

Introduction: Hypertensive cerebral small vessel disease (HTN-cSVD) is the predominant microangiopathy in patients with a combination of lobar and deep cerebral microbleeds (CMBs) and intracerebral hemorrhage (mixed ICH/CMB). We tested the hypothesis that cerebral amyloid angiopathy (CAA) is also a contributing microangiopathy in mixed ICH/CMB patients with cortical superficial siderosis (cSS), a marker that is strongly associated with CAA.

Methods: Brain MRIs from a prospective database of consecutive non-traumatic ICH patients admitted to a single referral center (2003 to 2019) were reviewed for the presence of CMBs, cSS, and non-hemorrhagic CAA markers (lobar lacunes, centrum semiovale enlarged perivascular spaces (CSO-EPVS), and multispot pattern of leukoaraiosis). The frequency of CAA markers and left ventricular hypertrophy (LVH), a marker for hypertensive end-organ damage, were compared between mixed ICH/CMB patients with cSS (mixed +cSS ) and without cSS (mixed -cSS ) in univariate and multivariate models.

Results: Of the 1824 ICH patients, 40 had mixed +cSS and 256 had mixed -cSS . LVH was less common in patients with mixed +cSS compared to those with mixed -cSS (34% vs. 59%, p = 0.01). The frequency of multispot pattern (18% vs. 4%, p < 0.01) and severe CSO-EPVS (33% vs. 11%, p < 0.01) were higher in patients with mixed +cSS compared to mixed -cSS , whereas lobar lacune frequency was similar (23% vs. 20%, p = 0.67). In a logistic regression model, older age (aOR 1.04 per year, 95% CI [1.01-1.08], p = 0.01), presence of multispot pattern (aOR 5.82, 95% CI [1.82-18.60], p < 0.03), severe CSO-EPVS (aOR 4.08, 95% CI [1.73-9.61], p < 0.01), and LVH (aOR 0.43, 95% CI [0.20-0.94], p = 0.03) were independently associated with mixed +cSS after further adjustment for sex and hypertension (Table).

Conclusions: CAA and HTN-cSVD appear to confer injury in patients with mixed ICH/CMB and cSS, a finding that warrants confirmation in studies incorporating advanced imaging/pathology.

Abstract 33: Risk Scores And Brain Mri Markers In Distinguishing Ischemic Stroke And Intracerebral Hemorrhage Risk Among Atrial Fibrillation Patients: The Neuro-Afib Study

Background: Recent studies cast doubt on the accuracy of the most-commonly used risk scores (CHA 2 DS 2 -VASC and HAS-BLED) in differentiating the risk of acute ischemic stroke (AIS) and intracerebral hemorrhage (ICH) among patients with fibrillation (AF). Because of the importance of AIS/ICH risk determination for choice of proper preventive approaches, we aimed to compare the value of these risk scores and brain MRI markers to differentiate the occurrence of AIS and ICH in a large cohort of AF-related strokes.

Methods: The Neuro-AFib study is a multicenter effort to elucidate the causes and consequences of AIS and ICH in AF patients. Demographics, CHA 2 DS 2 -VASC and HAS-BLED scores, and ischemic/hemorrhagic brain MRI markers were compared between AF patients admitted with AIS and ICH to 15 academic stroke centers in the US between 1/2018-12/2019.

Results: Of 5694 stroke admissions with AF, 4826 (84.8%) had AIS and 868 (15.2%) ICH. Mean age was similar between groups (75.9±11.5 vs 76.6±11.9, p=0.1), more ICH patients were male (57% vs 50%). Pre-index event CHA 2 DS 2 -VASC (4.14±1.6 vs 4.22±1.6) and HAS-BLED (2.71±1.09 vs 2.68±1.13) were similar between groups [both p>0.2]. Cerebral microbleeds (CMB, 56% vs 33.5%), cortical superficial siderosis (cSS, 15% vs 9.4%), and moderate-to-severe leukoaraiosis (41% vs 33.4%) were more commonly found among ICH patients compared to AIS (all p<0.001). Chronic lacunar infarcts (43.5% vs 39.5%, p=0.03) and chronic non-lacunar infarcts (29% vs 18%, p<0.001) were more commonly found in AIS. In a multivariable logistic regression model that included all variables above, male sex, presence of CMBs, cSS, moderate-to-severe leukoaraiosis were associated with ICH, chronic non-lacunar infarcts with AIS (all p<0.005), while CHA 2 DS 2 -VASC (p=0.9) and HAS-BLED (p=0.9) were not related to the stroke type.

Conclusions: Data from our multicenter study confirm the lack of specificity of CHA 2 DS 2 -VASC and HAS-BLED to categorize the risk of AIS vs ICH in AF patients. The chronic MRI findings (CMB, cSS, moderate-to-severe leukoaraiosis, chronic infarcts) should be incorporated into risk scores, and their predictive value for AIS and ICH should be investigated in prospective studies to select optimal stroke prevention methods in AF patients.

Improving detection of cerebral small vessel disease aetiology in patients with isolated lobar intracerebral haemorrhage

BACKGROUND AND PURPOSE

We evaluate whether non-haemorrhagic imaging markers (NHIM) (white matter hyperintensity patterns, lacunes and enlarged perivascular spaces (EPVS)) can discriminate cerebral amyloid angiopathy (CAA) from hypertensive cerebral small vessel disease (HTN-cSVD) among patients with isolated lobar intracerebral haemorrhage (isolated-LICH).

METHODS

In patients with isolated-LICH, four cSVD aetiologic groups were created by incorporating the presence/distribution of NHIM: HTN-cSVD pattern, CAA pattern, mixed NHIM and no NHIM. CAA pattern consisted of patients with any combination of severe centrum semiovale EPVS, lobar lacunes or multiple subcortical spots pattern. HTN-cSVD pattern consisted of any HTN-cSVD markers: severe basal ganglia PVS, deep lacunes or peribasal ganglia white matter hyperintensity pattern. Mixed NHIM consisted of at least one imaging marker from either pattern. Our hypothesis was that patients with HTN-cSVD pattern/mixed NHIM would have a higher frequency of left ventricular hypertrophy (LVH), which is associated with HTN-cSVD.

RESULTS

In 261 patients with isolated-LICH, CAA pattern was diagnosed in 93 patients, HTN-cSVD pattern in 53 patients, mixed NHIM in 19 patients and no NHIM in 96 patients. The frequency of LVH was similar among those with HTN-cSVD pattern and mixed NHIM (50% vs 39%, p=0.418) but was more frequent in HTN-cSVD pattern compared with CAA pattern (50% vs 20%, p<0.001). In a regression model, HTN-cSVD pattern (OR: 7.38; 95% CI 2.84 to 19.20) and mixed NHIM (OR: 4.45; 95% CI 1.25 to 15.90) were found to be independently associated with LVH.

CONCLUSION

Among patients with isolated-LICH, NHIM may help differentiate HTN-cSVD from CAA, using LVH as a marker for HTN-cSVD.

The Boston criteria version 2.0 for cerebral amyloid angiopathy: a multicentre, retrospective, MRI-neuropathology diagnostic accuracy study

BACKGROUND

Cerebral amyloid angiopathy (CAA) is an age-related small vessel disease, characterised pathologically by progressive deposition of amyloid β in the cerebrovascular wall. The Boston criteria are used worldwide for the in-vivo diagnosis of CAA but have not been updated since 2010, before the emergence of additional MRI markers. We report an international collaborative study aiming to update and externally validate the Boston diagnostic criteria across the full spectrum of clinical CAA presentations.

METHODS

In this multicentre, hospital-based, retrospective, MRI and neuropathology diagnostic accuracy study, we did a retrospective analysis of clinical, radiological, and histopathological data available to sites participating in the International CAA Association to formulate updated Boston criteria and establish their diagnostic accuracy across different populations and clinical presentations. Ten North American and European academic medical centres identified patients aged 50 years and older with potential CAA-related clinical presentations (ie, spontaneous intracerebral haemorrhage, cognitive impairment, or transient focal neurological episodes), available brain MRI, and histopathological assessment for CAA diagnosis. MRI scans were centrally rated at Massachusetts General Hospital (Boston, MA, USA) for haemorrhagic and non-haemorrhagic CAA markers, and brain tissue samples were rated by neuropathologists at the contributing sites. We derived the Boston criteria version 2.0 (v2.0) by selecting MRI features to optimise diagnostic specificity and sensitivity in a prespecified derivation cohort (Boston cases 1994-2012, n=159), then externally validated the criteria in a prespecified temporal validation cohort (Boston cases 2012-18, n=59) and a geographical validation cohort (non-Boston cases 2004-18; n=123), comparing accuracy of the new criteria to the currently used modified Boston criteria with histopathological assessment of CAA as the diagnostic standard. We also assessed performance of the v2.0 criteria in patients across all cohorts who had the diagnostic gold standard of brain autopsy.

FINDINGS

The study protocol was finalised on Jan 15, 2017, patient identification was completed on Dec 31, 2018, and imaging analyses were completed on Sept 30, 2019. Of 401 potentially eligible patients presenting to Massachusetts General Hospital, 218 were eligible to be included in the analysis; of 160 patient datasets from other centres, 123 were included. Using the derivation cohort, we derived provisional criteria for probable CAA requiring the presence of at least two strictly lobar haemorrhagic lesions (ie, intracerebral haemorrhages, cerebral microbleeds, or foci of cortical superficial siderosis) or at least one strictly lobar haemorrhagic lesion and at least one white matter characteristic (ie, severe visible perivascular spaces in centrum semiovale or white matter hyperintensities in a multispot pattern). The sensitivity and specificity of these criteria were 74·8% (95% CI 65·4-82·7) and 84·6% (71·9-93·1) in the derivation cohort, 92·5% (79·6-98·4) and 89·5% (66·9-98·7) in the temporal validation cohort, 80·2% (70·8-87·6) and 81·5% (61·9-93·7) in the geographical validation cohort, and 74·5% (65·4-82·4) and 95·0% (83·1-99·4) in all patients who had autopsy as the diagnostic standard. The area under the receiver operating characteristic curve (AUC) was 0·797 (0·732-0·861) in the derivation cohort, 0·910 (0·828-0·992) in the temporal validation cohort, 0·808 (0·724-0·893) in the geographical validation cohort, and 0·848 (0·794-0·901) in patients who had autopsy as the diagnostic standard. The v2.0 Boston criteria for probable CAA had superior accuracy to the current Boston criteria (sensitivity 64·5% [54·9-73·4]; specificity 95·0% [83·1-99·4]; AUC 0·798 [0·741-0854]; p=0·0005 for comparison of AUC) across all individuals who had autopsy as the diagnostic standard.

INTERPRETATION

The Boston criteria v2.0 incorporate emerging MRI markers of CAA to enhance sensitivity without compromising their specificity in our cohorts of patients aged 50 years and older presenting with spontaneous intracerebral haemorrhage, cognitive impairment, or transient focal neurological episodes. Future studies will be needed to determine generalisability of the v.2.0 criteria across the full range of patients and clinical presentations.

FUNDING

US National Institutes of Health (R01 AG26484).

Idiopathic primary intraventricular hemorrhage and cerebral small vessel disease

BACKGROUND

Although primary intraventricular hemorrhage is frequently due to trauma or vascular lesions, the etiology of idiopathic primary intraventricular hemorrhage (IP-IVH) is not defined.

AIMS

Herein, we test the hypothesis that cerebral small vessel diseases (cSVD) including hypertensive cSVD (HTN-cSVD) and cerebral amyloid angiopathy are associated with IP-IVH.

METHODS

Brain magnetic resonance imaging from consecutive patients (January 2011 to September 2019) with non-traumatic intracerebral hemorrhage from a single referral center were reviewed for the presence of HTN-cSVD (defined by strictly deep or mixed-location intracerebral hemorrhage/cerebral microbleeds) and cerebral amyloid angiopathy (applying modified Boston criteria).

RESULTS

Forty-six (4%) out of 1276 patients were identified as having IP-IVH. Among these, the mean age was 74.4 ± 12.2 years and 18 (39%) were females. Forty (87%) had hypertension, and the mean initial blood pressure was 169.2 ± 40.4/88.8 ± 22.2 mmHg. Of the 35 (76%) patients who received a brain magnetic resonance imaging, two (6%) fulfilled the modified Boston criteria for possible cerebral amyloid angiopathy and 10 (29%) for probable cerebral amyloid angiopathy. Probable cerebral amyloid angiopathy was found at a similar frequency when comparing IP-IVH patients to the remaining patients with primary intraparenchymal hemorrhage (P-IPH) (27%, p = 0.85). Furthermore, imaging evidence for HTN-cSVD was found in 8 (24%) patients with IP-IVH compared to 209 (28%, p = 0.52) patients with P-IPH.

CONCLUSIONS

Among IP-IVH patients, cerebral amyloid angiopathy was found in approximately one-third of patients, whereas HTN-cSVD was detected in 23%-both similar rates to P-IPH patients. Our results suggest that both cSVD subtypes may be associated with IP-IVH.

Effect of vascular amyloid on white matter disease is mediated by vascular dysfunction in cerebral amyloid angiopathy

We postulated that vascular dysfunction mediates the relationship between amyloid load and white matter hyperintensities (WMH) in cerebral amyloid angiopathy (CAA). Thirty-eight cognitively healthy patients with CAA (mean age 70 ± 7.1) were evaluated. WMH was quantified and expressed as percent of total intracranial volume (pWMH) using structural MRI. Mean global cortical Distribution Volume Ratio representing Pittsburgh Compound B (PiB) uptake (PiB-DVR) was calculated from PET scans. Time-to-peak [TTP] of blood oxygen level-dependent response to visual stimulation was used as an fMRI measure of vascular dysfunction. Higher PiB-DVR correlated with prolonged TTP (r = 0.373, p = 0.021) and higher pWMH (r = 0.337, p = 0.039). Prolonged TTP also correlated with higher pWMH (r = 0.485, p = 0.002). In a multivariate linear regression model, TTP remained independently associated with pWMH (p = 0.006) while PiB-DVR did not (p = 0.225). In a bootstrapping model, TTP had a significant indirect effect (ab = 0.97, 95% CI: 0.137-2.461), supporting that the association between PiB-DVR and pWMH is mediated by TTP response. There was no longer a direct effect independent of the hypothesized pathway. Our study suggests that the effect of vascular amyloid load on white matter disease is mediated by vascular dysfunction in CAA. Amyloid lowering strategies might prevent pathophysiological processes leading to vascular dysfunction, therefore limiting ischemic brain injury.

Cerebellar atrophy and its implications on gait in cerebral amyloid angiopathy

OBJECTIVE

Recent data suggest that cerebral amyloid angiopathy (CAA) causes haemorrhagic lesions in cerebellar cortex as well as subcortical cerebral atrophy. However, the potential effect of CAA on cerebellar tissue loss and its clinical implications have not been investigated.

METHODS

Our study included 70 non-demented patients with probable CAA, 70 age-matched healthy controls (HCs) and 70 age-matched patients with Alzheimer's disease (AD). The cerebellum was segmented into percent of cerebellar subcortical volume (pCbll-ScV) and percent of cerebellar cortical volume (pCbll-CV) represented as percent (p) of estimated total intracranial volume. We compared pCbll-ScV and pCbll-CV between patients with CAA, HCs and those with AD. Gait velocity (metres/second) was used to investigate gait function in patients with CAA.

RESULTS

Patients with CAA had significantly lower pCbll-ScV compared with both HC (1.49±0.1 vs 1.73±0.2, p<0.001) and AD (1.49±0.1 vs 1.66±0.24, p<0.001) and lower pCbll-CV compared with HCs (6.03±0.5 vs 6.23±0.6, p=0.028). Diagnosis of CAA was independently associated with lower pCbll-ScV compared with HCs (p<0.001) and patients with AD (p<0.001) in separate linear regression models adjusted for age, sex and presence of hypertension. Lower pCbll-ScV was independently associated with worse gait velocity (β=0.736, 95% CI 0.28 to 1.19, p=0.002) in a stepwise linear regression analysis including pCbll-CV along with other relevant variables.

INTERPRETATION

Patients with CAA show more subcortical cerebellar atrophy than HC or patients with AD and more cortical cerebellar atrophy than HCs. Reduced pCbll-ScV correlated with lower gait velocity in regression models including other relevant variables. Overall, this study suggests that CAA causes cerebellar injury, which might contribute to gait disturbance.

Corpus callosum lesions are associated with worse cognitive performance in cerebral amyloid angiopathy

The impact of vascular lesions on cognition is location dependent. Here, we assessed the contribution of small vessel disease lesions in the corpus callosum to vascular cognitive impairment in cerebral amyloid angiopathy, as a model for cerebral small vessel disease. Sixty-five patients with probable cerebral amyloid angiopathy underwent 3T magnetic resonance imaging, including a diffusion tensor imaging scan, and neuropsychological testing. Microstructural white-matter integrity was quantified by fractional anisotropy and mean diffusivity. Z-scores on individual neuropsychological tests were averaged into five cognitive domains: information processing speed, executive functioning, memory, language and visuospatial ability. Corpus callosum lesions were defined as haemorrhagic (microbleeds or larger bleeds) or ischaemic (microinfarcts, larger infarcts and diffuse fluid-attenuated inversion recovery hyperintensities). Associations between corpus callosum lesion presence, microstructural white-matter integrity and cognitive performance were examined with multiple regression models. The prevalence of corpus callosum lesions was confirmed in an independent cohort of memory clinic patients with and without cerebral amyloid angiopathy (n = 82). In parallel, we assessed corpus callosum lesions on ex vivo magnetic resonance imaging in cerebral amyloid angiopathy patients (n = 19) and controls (n = 5) and determined associated tissue abnormalities with histopathology. A total number of 21 corpus callosum lesions was found in 19/65 (29%) cerebral amyloid angiopathy patients. Corpus callosum lesion presence was associated with reduced microstructural white-matter integrity within the corpus callosum and in the whole-brain white matter. Patients with corpus callosum lesions performed significantly worse on all cognitive domains except language, compared with those without corpus callosum lesions after correcting for age, sex, education and time between magnetic resonance imaging and neuropsychological assessment. This association was independent of the presence of intracerebral haemorrhage, whole-brain fractional anisotropy and mean diffusivity, and white-matter hyperintensity volume and brain volume for the domains of information processing speed and executive functioning. In the memory clinic patient cohort, corpus callosum lesions were present in 14/54 (26%) patients with probable and 2/8 (25%) patients with possible cerebral amyloid angiopathy, and in 3/20 (15%) patients without cerebral amyloid angiopathy. In the ex vivo cohort, corpus callosum lesions were present in 10/19 (53%) patients and 2/5 (40%) controls. On histopathology, ischaemic corpus callosum lesions were associated with tissue loss and demyelination, which extended beyond the lesion core. Together, these data suggest that corpus callosum lesions are a frequent finding in cerebral amyloid angiopathy, and that they independently contribute to cognitive impairment through strategic microstructural disruption of white-matter tracts.

Abstract 69: Extent Of Tau And Its Cognitive Implications In Cerebral Amyloid Angiopathy

Background: Tau pathology is an important component of Alzheimer’s Disease but its extent and impact in cognitively healthy patients with cerebral amyloid angiopathy (CAA) are not clear. We compared in vivo tau stages estimated from the patterns of tau PET tracer uptake in patients with CAA and healthy controls (HC) and explored its relationship with amyloid burden and cognitive function in CAA.

Methods: The study included 50 cognitively healthy probable CAA patients (mean age 70±7.6) and 50 age-, sex-matched HCs (mean age 70±7.5) who underwent MRI, Pittsburgh compound B (PiB, for amyloid) and 18 F-flortaucipir (FTP, for tau) PET imaging. Mean global cortical PiB uptake was calculated. Tau stages were estimated based on the distribution pattern of cortical FTP uptake and grouped into three categories (PET Braak Staging, Figure). Within the CAA cohort, standardized z-scores of memory, processing speed and executive function testing were obtained.

Results: In the whole group, tau stages significantly correlated with age (rho=0.407, p<0.001) and global cortical PiB uptake (rho=0.554, p<0.001). Patients with CAA were more likely to exhibit more extensive tau (Stage III-VI) compared to HCs in univariate analyses (Figure, p=0.003). In a logistic regression model, more extensive tau independently associated with age (p=0.001) and PiB uptake (p<0.001) but not with the CAA diagnosis (p=0.264). Within the CAA cohort, tau stage was again independently associated with PiB uptake (p=0.002), but it did not show any association with scores of cognitive domains in univariate or multivariate models (p>0.2 for all comparisons).

Conclusion: Our results show that patients with CAA have higher PET Braak tau stages when compared to similarly aged HCs but this difference disappeared after controlling for amyloid load. Extent of tau did not correlate with cognitive scores in CAA. Overall, tau stages appear to be driven by amyloid without clinical impact in cognitively healthy CAA patients.

Abstract 157: Ischemic Strokes In Patients With Atrial Fibrillation On Oral Anticoagulant: The Neuro-AFib Study

Background: Ischemic stroke (IS) admissions in patients with atrial fibrillation (AF) using either direct oral anticoagulants (DOAC) or Vitamin K antagonists (VKA) are commonly seen in stroke units but data on their prevalence and causes are scarce. Understanding the frequency/causes of failures of current FDA-approved preventive methods in patients with AF is important to reduce stroke risk and related death/disability.

Methods: The Neuro-AFib study is a multicenter effort geared toward elucidating the causes and consequences of IS and hemorrhagic stroke in a contemporary AF cohort. Detailed clinical, laboratory and multimodal neuro- and cardiac imaging data from known AF patients consecutively admitted to 22 US academic stroke centers with an IS between 1/2018-12/2019 were used to compare characteristics of IS on vs off oral anticoagulants.

Results: Out of 6443 IS patients with AF, 4898 (76%) had known AF prior to the acute stroke. Among these patients with known AF, 2204 (45%) were using oral anticoagulants [OAC= DOAC (59.3%) or VKA (40.7%)]. Patients who had IS on OAC were younger (76.8 + 11 vs 78 + 12, p=0.001), had higher mean CHA 2 DS 2 -VASc scores (4.17 + 1.5 vs 3.9 + 1.5, p<0.0001), and more likely to have a past history of IS/TIA when compared to non-OAC group (35% vs 23%, p<0.0001). In a multivariable logistic regression model, history of IS/TIA, diabetes, hyperlipidemia, heart failure, prosthetic heart valve, sleep apnea, permanent atrial fibrillation, left atrial dilation and ischemic arterial disease were all independently associated with IS on OAC (all p<0.05). Imaging data were complete in 15% of the cohort and IS on OAC group had more acute lacunar infarcts, and extracranial and intracranial atherosclerotic disease causing 50% or more ipsilateral stenosis compared to patients with IS off OAC (all p<0.05).

Conclusions: Based on a large multicenter contemporary cohort of IS patients with known AF, the numbers of patients who failed OACs (and especially DOACs) are high. These patients have severe vascular risk factor loads, concurrent etiologies, and they are more likely to have recurrent ischemic events. Further detailed data focused on imaging and IS mechanisms from this contemporary cohort will be ready to be presented during ISC 2022.

Abstract WMP78: Microstructural Alterations And Vascular Dysfunction In Cerebral Amyloid Angiopathy

Background: Cerebral amyloid angiopathy (CAA) causes impaired vascular reactivity to physiologic stimuli that mediates CAA-related white matter hyperintensities (WMH) but its relationship to microstructural changes has not yet been tested. We hypothesized that the degree of vascular dysfunction would be associated with alterations in white matter microstructure in patients with CAA.

Methods: Fifty-five non-demented probable CAA patients underwent high-resolution structural MRI including Diffusion-Weighted Imaging (DWI) and functional MRI (fMRI). WMH volume was quantified and expressed as percent of total intracranial volume (pWMH). Vascular reactivity was measured as the amplitude of the blood-oxygenation-level-dependent response (BOLD_Amp) to a visual stimulus. Peak Width of Skeletonized Mean Diffusivity (PSMD) was calculated from DWI and used as a marker of microstructural integrity.

Results: Patients had a mean age of 69.3±7.4 years and 36 (65%) had intracerebral hemorrhage (ICH). The mean PSMD was [(3.92±0.8) х 10–4 mm2/s] and the mean BOLD_Amp was 1.15±0.2%. Neither PSMD nor BOLD_Amp differed between patients with ICH and those without (p>0.2 for all comparisons). PSMD significantly correlated with older age (r=0.335, p=0.012), with higher pWMH (r=0.792, p<0.001) and with lower BOLD_Amp (r= –0.5, p<0.001). PSMD showed a trend to increase more in patients with hypertension (HT) than without ([(4.09±0.8) х 10–4 mm2/s] vs. ([(3.74±0.8) х 10–4 mm2/s], p=0.097). BOLD_Amp also correlated with pWMH (r= –0.409, p=0.002). In a linear regression analysis, decrease in BOLD_Amp was independently associated with increased PSMD corrected for age, sex, HTN, ICH and pWMH (β= –0.91, 95%CI (–1.77)-(–0.05), p=0.037). pWMH was also associated with PSMD in this model (β=1.22, 95%CI 0.89-1.54, p<0.001).

Conclusion: This study supports the view that vascular dysfunction in CAA is closely linked with CAA-related global ischemic injury including MRI-visible white matter injury as well as microstructural tissue disruption.

Abstract WMP101: Potential Causes Of Anticoagulant Underuse In Patients With Atrial Fibrillation Presenting With Ischemic Strokes

Background: Underuse of FDA-approved stroke prevention methods in atrial fibrillation (AF) remains a major problem. We aimed to explore the potential causes of oral anticoagulant (OAC) non-use and compare the frequency of these factors between AF patients with acute ischemic stroke (AIS) off and on oral anticoagulant (OAC).

Methods: The Neuro-AFib study is a multicenter observational study aiming to clarify the causes of different stroke types in a contemporary AF cohort. Potential causes of OAC non-use were systematically collected from all enrolled patients based on the exclusion criteria of the Direct OAC (DOAC) studies. The frequency of potential causes of OAC non-use (AIS-off-OAC) are explored in AF patients consecutively admitted to 22 US academic stroke centers with an AIS between 1/2018-12/2019, and these rates are compared to AIS-on-OAC.

Results: Among 4898 patients with known AF who had IS, 2694 (55%) were not using any OAC, and 45% were AIS-on-OAC. CHA2DS2-VASc <2, the cutoff representing low embolic risk until late 2019, was found in 7% of AIS-off-OAC group compared to 3.8% in AIS-on-OAC (p<0.0001). The most common factor in OAC non-use group was history of falls (26%) vs 18% in AIS-on-OAC group (p=0.004). History of bleeding [intracranial (2.3%) and extracranial (18.5%)] was found in 20.8% of AIS-off-OAC vs 10.4% of AIS-on-OAC group (p<0.0001). 82.6% of these hemorrhages were classified as major bleeds. Pre-stroke cognitive impairment was also common in AIS-off-OAC (21.7%). Renal failure (creatinine >2mg/dl) was found in 13% of AIS-off-OAC. Gait problems leading to limited mobility (10%) and excessive alcohol use (3.8%) were other potential factors for OAC non-use. Among OAC non-users, 64% had at least one risk factor defined above.

Conclusions: In a large multicenter contemporary IS cohort with known AF, 55% of patients were not on OAC, and about two thirds of them had a reason that would exclude them from the phase 3 DOAC studies. Other than improving the accuracy of risk prediction algorithms, research should focus on identifying optimal management approaches for this large AF population who present challenges to lifelong OAC use. FDA-approved left atrial appendage closure procedures can be considered in such AF patients.

Lacunes, Microinfarcts, and Vascular Dysfunction in Cerebral Amyloid Angiopathy

OBJECTIVE

To analyze the relationship of lacunes with cortical cerebral microinfarcts (CMIs), to assess their association with vascular dysfunction, and to evaluate their effect on the risk of incident intracerebral hemorrhage (ICH) in cerebral amyloid angiopathy (CAA).

METHODS

The count and topography of lacunes (deep/lobar), CMIs, and white matter hyperintensity (WMH) volume were retrospectively analyzed in a prospectively enrolled CAA cohort that underwent high-resolution research MRIs. The relationship of lacunes with CMIs and other CAA-related markers including time to peak (TTP) of blood oxygen level-dependent signal, an established measure of vascular dysfunction, was evaluated in multivariate models. Adjusted Cox regression models were used to investigate the relationship between lacunes and incident ICH.

RESULTS

The cohort consisted of 122 patients with probable CAA without dementia (mean age, 69.4 ± 7.6 years). Lacunes were present in 31 patients (25.4%); all but one were located in lobar regions. Cortical CMIs were more common in patients with lacunes compared to patients without lacunes (51.6% vs 20.9%, p = 0.002). TTP was not associated with either lacunes or CMIs (both p > 0.2) but longer TTP response independently correlated with higher WMH volume (p = 0.001). Lacunes were associated with increased ICH risk in univariate and multivariate Cox regression models (p = 0.048 and p = 0.026, respectively).

CONCLUSIONS

Our findings show a high prevalence of lobar lacunes, frequently coexisting with CMIs in CAA, suggesting that these 2 lesion types may be part of a common spectrum of CAA-related infarcts. Lacunes were not related to vascular dysfunction but predicted incident ICH, favoring severe focal vessel involvement rather than global ischemia as their mechanism.

Abstract P617: Ischemic Strokes in Patients With Atrial Fibrillation: The Neuro-AFib Study

Background: An estimated 150,000 atrial fibrillation (AF) patients suffer an ischemic stroke (IS) annually in the US. Understanding the frequency/causes of underuse and failures of current FDA-approved preventive methods in patients with known AF may reduce stroke risk and related death/disability.

Methods: The Neuro-AFib study is a multicenter effort geared toward elucidating the causes and consequences of IS and hemorrhagic stroke (HS) in a contemporary AF cohort. The retrospective phase of the study is underway, aiming to obtain detailed clinical, laboratory and multimodal neuro- and cardiac imaging data from ~9,000 AF patients admitted to 30 US academic stroke centers with an IS or HS between 1/2018-12/2019. Clinical data of IS admissions from 12 sites will be discussed. Disability is defined as a modified Rankin Score (mRS) 3-5, outcomes are from the time of hospital discharge.

Results: A total of 3944 AF patients presented with an IS, mean age was 76.8 + 12, and 50.2% were female. AF was diagnosed prior to IS in 78% of patients. Data on prestroke antithrombotic usage, embolic risk scores, clinical stroke severity and outcomes are presented in the FIGURE.

Conclusions: Preliminary results from the Neuro-AFib study show high rates of underuse of approved stroke prevention measures (54%) and anticoagulant failures (46%) that result into IS even in known AF patients. Relatively high rates of pre-stroke AF detection failures were also noted (22%). Death/disability rates were high in all of these AF-related IS patients ( > 69%). Detailed data collection focused on imaging and lab markers of stroke risk from this contemporary cohort will be ready to be presented during ISC 2021.

Abstract 9: Peak Width of Skeletonized Mean Diffusivity and Cognition in Cerebral Amyloid Angiopathy

Background: We hypothesized that Peak Width of Skeletonized Mean Diffusivity (PSMD), an automated marker of cerebral microangiopathy representing microstructural disruption of white matter (WM), would be increased in patients with cerebral amyloid angiopathy (CAA) compared to healthy controls (HCs) and increased PSMD would be associated with lower processing speed scores (PSSs) in patients with CAA.

Methods: Seventy-two nondemented probable CAA patients and 23 HCs prospectively underwent high-resolution brain MRIs and cognitive tests. PSMD scores were quantified from a probabilistic skeleton of the WM tracts as previously validated (http://www.psmd-marker.com). In subjects with intracerebral hemorrhage (ICH, n=27), ICH regions were masked and removed from the PSMD pipeline. The analyses were repeated in the non-ICH hemisphere. Raw scores of Trail Making Test-B and Symbol Substitution Test were transformed into standardized z -scores and averaged to obtain PSSs.

Results: The mean age (p=0.366) and sex (p=0.811) were similar between CAA patients and HCs. PSMD was higher in the CAA group [(3.95±0.9) х 10 –4 mm 2 /s] compared to HCs [(3.32±0.6) х 10 –4 mm 2 /s] (p=0.003). This association remained significant in a linear regression model corrected for age and sex (β=0.700, 95%CI 0.3-1, p=0.001). Within the CAA cohort, higher PSMD was associated with higher WM hyperintensity volume in a multiple regression model adjusted for all relevant variables (β=0.890, 95%CI 0.7-1, p<0.001). In a regression model corrected for age, sex, years of education and presence of ICH, a lower PSS was independently associated with increased PSMD (β=-0.405, 95%CI {-0.6}-{-0.2}, p<0.001). These results did not change when the non-ICH hemisphere was used for PSMD processing.

Conclusion: PSMD is increased in CAA and is associated with worse PSSs supporting the view that disruption of white matter has a significant role in cognitive impairment in CAA.

Abstract P442: The Association of Amyloid and Tau Burden With Centrum Semiovale Perivascular Spaces in Cerebral Amyloid Angiopathy

Background: The mechanisms linking cerebral amyloid angiopathy (CAA) to enlarged perivascular spaces in centrum semiovale (CSO-EPVS) and whether other Alzheimer’s Disease (AD) pathologies might affect CSO-EPVS are unclear. We hypothesized that amyloid but not tau load would independently correlate with CSO-EPVS in CAA.

Methods: Fifty prospectively enrolled nondemented probable CAA patients underwent high-resolution structural MRI, Pittsburgh compound B (PiB, for amyloid), and 18 F-flortaucipir (FTP, for tau) PET imaging. Microbleeds (all lobar, LMB) were counted and white matter hyperintensity volume (WMH) was quantified. CSO-EPVS were counted on T 2 -MRI sequence and graded using a previously validated scale (range 0-4). A multivariate ordinal regression model was used to assess the independent associations between CSO-EPVS and mean cortical amyloid as well as tau deposition, after adjusting for relevant covariates.

Results: Patients had a mean age of 69.3±7.2. Age, sex, presence of hypertension, intracerebral hemorrhage (ICH), LMB counts, and WMH were not associated with CSO-EPVS grades (p>0.2 for all comparisons). Higher PiB uptake significantly correlated with increased CSO-EPVS (rho=0.45, p=0.001). Higher FTP showed a trend for correlation with CSO-EPVS (rho=0.26, p=0.069). In an ordinal regression model with CSO-EPVS grade as the dependent variable and both amyloid and tau levels included as predictors along with covariates presented above, the association of CSO-EPVS remained significant with higher PiB uptake (β=3.97, 95%CI 1.1-6.8, p=0.007) but not with FTP uptake (p=0.167).

Conclusion: Results of this study suggest that CSO-EPVS is independently associated with amyloid but not with tau deposition in CAA. CSO-EPVS was not associated with age or classical vascular risk factors or presence of ICH. Our results support the view that vascular amyloid but not other AD pathologies such as tau might contribute to EPVS in patients with CAA.

Abstract P409: Cerebellar Atrophy and Its Clinical Implications in Cerebral Amyloid Angiopathy

Background: Recent data show that cerebral amyloid angiopathy (CAA) might cause hemorrhagic lesions in cerebellar cortex as well as cerebral atrophy. However, the potential effect of CAA on cerebellar tissue loss and its clinical implications have not been investigated.

Methods: We compared cerebellar volumes in 70 nondemented patients with probable CAA to 70 age-matched healthy controls (HC) and 70 age-matched Alzheimer’s disease (AD) patients. Volumetric analyses including cerebellar cortical volume (pCbll-CV), cerebellar subcortical volume (pCbll-ScV), cerebral white matter volume (pWMV), and cerebral white matter hyperintensity volume (pWMH) were calculated as percent of total intracranial volume. Gait velocity (meters/seconds) was used to investigate the potential effect of cerebellar tissue loss on gait function.

Results: Patients with CAA had significantly lower pCbll-ScV and pCbll-CV compared to HC (1.49%±0.17 vs 1.71%±0.23, p<0.001 and 6.03%±0.50 vs 6.23%±0.56, p<0.027 respectively). When compared to AD, pCbll-ScV but not pCbll-CV was significantly lower in CAA (1.49%±0.17 vs 1.670.24, p<0.001). Diagnosis of CAA was independently associated with lower pCbll-ScV in a general linear model adjusting for age, sex and presence of hypertension when compared to both HCs and patients with AD (p<0.0001 for all associations, after Bonferroni correction for multiple comparisons). Lower pCbll-ScV was associated with lower gait velocity score in univariate and multivariate analysis adjusted for relevant variables (adjusted β=0.826, 95%CI 0.357-1.295, p=0.001).

Conclusion: Patients with CAA show cerebellar atrophy; predominantly in the subcortical cerebellum when compared to both HC and AD patients. Cerebellar tissue loss independently correlated with worse gait function in CAA patients. Overall, this study supports the view that CAA causes cerebellar injury which might mediate gait disturbance in patients with CAA.

Abstract 38: Hemorrhagic Strokes in Patients With Atrial Fibrillation: The Neuro-AFib Study

Background: We aimed to compare the clinical features and short-term outcomes of hemorrhagic stroke (HS) to ischemic stroke (IS) in atrial fibrillation (AF) patients using a large contemporary cohort.

Methods: The Neuro-AFib study is a multicenter effort to elucidate the current causes and consequences of IS and HS in AF patients. The retrospective phase of the study is underway, aimed at obtaining detailed clinical, laboratory and multimodal neuro- and cardiac imaging data from ~9,000 patients with AF admitted to 30 academic stroke centers in the US with an IS or HS between 1/2018-12/2019. Preliminary clinical data from 12 sites are presented in this abstract.

Results: Of 4764 stroke admissions with AF, 820 (17.2%) had HS and 3944 IS. Patients with HS were younger (74.8 + 12 vs 76.8 + 12), more likely to be male (54% vs 46%) and had lower CHA 2 DS 2 -VASC (3.6 + 1.6 vs 3.9 + 1.6) than IS [all p<0.05]. Patients with HS were more likely to be on AC compared to IS (60% vs 38%, p<0.001). Within the HS cohort, 32% were on direct oral anticoagulant, 28% on warfarin, 16% on antiplatelet, and 24% on no antithrombotic. Patients with HS had worse outcomes than IS in terms of in hospital case fatality (32.4 vs 10.3%, p<0.001) and severe disability (modified Rankin Scale 4-5) at discharge (63.3% vs 53.7%, p=0.002) despite similar rates of severe disability before admission (7% vs 6.2%, p=0.73). All of the reported associations remained significant after adjustment for age, sex and other relevant covariates.

Conclusions: Preliminary findings from the Neuro-AFib study show significantly worse outcomes for HS compared to IS in AF patients, with triple case fatality and elevated severe disability risks. These results showcase the importance of identifying AF patients at high HS risk. Detailed imaging markers of HS risk including microbleeds, superficial siderosis, leukoaraiosis within the full cohort will be analyzed and discussed during ISC 2021.

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.

Alexithymia is a non motor symptom of essential tremor regardless of the presence of depression and anxiety

OBJECTIVE

Essential tremor (ET) is one of the most common movement disorders. Aside from tremor, patients may exhibit other motor features as well as non-motor features, including neuropsychiatric symptoms. The cerebellum and cerebellar connections are thought to play a key role in the pathophysiology of ET. Cognitive and affective disturbances can occur in the context of cerebellar disease. Our aim was to study the prevalence and clinical correlates of alexithymia and its relationship to depression and anxiety in ET patients and control subjects (CS).

METHOD

We enrolled 100 ET patients and 100 age- and gender-matched CS. The Toronto Alexithymia Scale-20 (TAS-20), the Beck depression inventory-II and the Beck anxiety inventory were administered.

RESULTS

Alexithymia levels were significantly higher in ET patients than CS (respective mean TAS-20 scores = 50.63 ± 9.79 vs. 44.05 ± 12.51, p < 0.001).  There were robust associations between alexithymia, depressive symptoms, and anxiety but, after excluding the ET patients and the CS who had moderate or severe depression or who had moderate or severe anxiety, the total alexithymia score remained significantly higher in the ET than the CS group (46.78 ± 9.19 vs. 41.18 ± 11.79, p ≤ 0.01).

CONCLUSION

This study suggests that prevalence of alexithymia is significantly higher in ET patients. Alexithymia might be another non-motor neuropsychiatric symptom of the disease.  Further studies are needed to confirm and expand upon our findings.

White matter atrophy in cerebral amyloid angiopathy

OBJECTIVE

We postulated that cerebral amyloid angiopathy (CAA) is associated with white matter atrophy (WMA) and that WMA can be related to cognitive changes in CAA.

METHODS

White matter volume expressed as percent of intracranial volume (pWMV) of prospectively enrolled patients without dementia diagnosed with probable CAA was compared to age-matched healthy controls (HC) and patients with Alzheimer disease (AD). Cognitive scores were also sought to understand the potential effects of WMA on cognitive function.

RESULTS

Patients with CAA (n = 72) had significantly lower pWMV (27.97% ± 2.63) when compared to age-matched HC (n = 72; mean difference [MD], 2.38%; p < 0.0001) and patients with AD (n = 72; MD, 1.57%; p < 0.0001). Differences were most pronounced in the posterior occipital regions in both comparisons. When comparisons were restricted to groups of patients with CAA but no intracerebral hemorrhage (n = 32) or hypertension (n = 32), and age-matched HC and AD, the significant differences were unaltered. Within the CAA cohort, higher age, lobar microbleed counts, and presence of hypertension were associated with lower pWMV (p = 0.0007, p = 0.031, and p = 0.003, respectively). All associations remained independent in multivariable analyses. Within the CAA cohort, higher pWMV independently correlated with better scores of executive function.

CONCLUSIONS

Patients with CAA show WMA when compared to age-matched HC and patients with AD. WMA independently correlates with the number of lobar microbleeds, a marker of CAA severity. Consistent spatial patterns of WMA especially in posterior regions might be related to CAA. The association between WMA and measures of executive function suggests that WMA might represent an important mediator of CAA-related neurologic dysfunction.

Abstract WP417: Relevance of Lobar Cerebral Microbleeds in Patients With Deep Intracerebral Hemorrhage

Background: Markers of cerebral small vessel disease (cSVD) severity and prognosis in strictly lobar or strictly deep intracerebral hemorrhages (ICH)/cerebral microbleeds (CMB) are well defined but data are scarce for mixed-location ICH/CMB. We aimed to compare neuroimaging features and outcomes between deep ICH patients with and without lobar CMBs.

Methods: Patients with first-ever deep ICH from a prospectively maintained single-center registry were analyzed. Demographics, risk factors and neuroimaging markers of cSVD including CMBs, cortical superficial siderosis, enlarged perivascular spaces (EPVS), white matter hyperintensity volumes (WMH) and brain atrophy scores (range 0-15) were compared between deep ICH patients with lobar CMBs and those without lobar CMBs. The follow-up data were analyzed for ICH recurrence, ischemic stroke (IS) and all-cause mortality.

Results: Of 208 patients, 98 (47.1%) had lobar CMBs. Patients with L-CMBs were older (65.3±12.1 vs. 57.4±12.5, p<0.001) and more likely to be hypertensive (98% vs. 90.9%, p=0.037) than those without L-CMBs. Deep CMBs (83.7% vs 56.4%, p<0.001), lacunes (53.1% vs 31.8%, p=0.003) and severe basal ganglia EPVS (40.8% vs 17.3%, p<0.001) were more common in patients with L-CMBs. Patients with L-CMBs had higher volumes of WMH (17.4 ml [IQR 9-38] vs 4.8 ml [IQR 1-13], p<0.001) and atrophy scores (4 [IQR 2-7] vs 3 [IQR 0-6], p=0.007) as compared to patients without L-CMBs. During a median follow-up of 21 months, the ICH recurrence rate was similar between groups (p=0.2), but higher incident IS (3.0 vs 0.0 per 1000-person-months, p=0.016) and all-cause mortality (4.9 vs 1.5 per 1000-person-months, p=0.026) were observed in patients with L-CMBs. In a cox regression model, the presence of lobar CMBs was independently associated with a composite outcome measure (ICH/IS/mortality) after adjusting for age, hypertension, WMH volume, lacune, BG-EPVS and atrophy scores (odds ratio: 2.9, 95%CI:1.01-8.4 p=0.046).

Conclusions: Presence of lobar CMBs in patients with deep ICH is associated with parenchymal markers of more severe cSVD and poor prognosis, suggesting a more advanced vasculopathy compared to patients with strictly deep ICH.

Abstract 16: Functional Magnetic Resonance Imaging as a Predictor of Cognitive Impairment in Cerebral Amyloid Angiopathy

Background: Cerebral Amyloid Angiopathy (CAA) emerged as an important contributor to cognitive impairment (CI) in elderly. Multiple lines of evidence suggest the presence of vascular dysfunction in CAA but its relationship to CI has not been tested. We hypothesized that the degree of vascular dysfunction identified by functional magnetic resonance imaging (fMRI) is a predictor of subsequent development of CI in patients with CAA.

Methods: Thirty nondemented probable CAA patients diagnosed with Boston criteria were prospectively enrolled. They underwent high-resolution structural MRI and fMRI at baseline and cognitive assessment both at baseline and follow up. Structural MRI markers (microbleed counts, superficial siderosis, enlarged perivascular spaces, cortical microinfarcts) and FreeSurfer based volumetric analyses (cortical thickness, white matter hyperintensity volume) were obtained. An fMRI measure of vascular reactivity to visual stimulation, time-to-peak [TTP] of blood oxygen level-dependent [BOLD] response, was the main physiologic marker of interest. Main outcome measure was the development of CI defined based on structured cognitive assessments.

Results: Patients had a mean age of 69.1±7.6 years. During a median follow-up of 23 months, 13 patients (43.3%) developed CI. Patients who developed CI did not differ from the patients without CI in terms of age, sex, risk factors and structural MRI markers (all p>0.2). Patients with CI trended towards fewer years of education (16±2.8 years vs 18±2.8 years, p=0.069). Baseline TTP of BOLD response was significantly higher in patients with incident CI as compared to patients without CI (12.7 ± 5.8 vs 7.8 ± 2.9, p=0.005). In a cox regression analysis, higher TTP was independently associated with future CI risk, after adjusting for age, sex, WMH volumes and education years (hazard ratio: 1.23; 95% CI: 1.06-1.42; p=0.006).

Conclusion: The severity of baseline vascular dysfunction is associated with future CI in CAA. Unlike markers of parenchymal injury that are typically irreversible, vascular dysfunction might be reversible making our findings potentially relevant to future therapeutic development efforts.

Abstract WP238: Atrial Fibrillation is Associated With Severe Basal Ganglia Perivascular Spaces

Introduction: High burdens of basal ganglia-perivascular spaces (BG-PVS) are often attributed to underlying hypertensive cerebral small vessel disease (HTN-CSVD). Although PVS are thought to arise from decreased perivascular drainage related to changes in arterial pulsatility, the contribution of pulsatility changes from nonvalvular atrial fibrillation (NVAF) has not been studied.

Hypothesis: We hypothesized that NVAF patients have a higher burden of BG-PVS than HTN-CSVD patients, possibly through hemodynamic factors related to NVAF.

Methods: Through an observational single-center study of consecutive stroke patients, we compared BG-EPVS severity between 136 patients with NVAF-related ischemic stroke (NVAF-IS) and 107 patients with HTN-CSVD-related intracerebral hemorrhage (HTN-ICH) without NVAF. Within the NVAF cohort, we also built multiple regression models to evaluate independent effects of NVAF-related factors on BG-PVS. All multiple regression models were adjusted for age, hypertension, sex, and neuroimaging markers of CSVD (extent of white matter hyperintensities (WMH), presence of lacunes, and cerebral microbleeds).

Results: Patients with NVAF-IS were older than patients with HTN-ICH (75 + 12 vs. 64 + 13, p < 0.0001); however, there was no difference in sex between groups ( p = 0.6). Severe BG-PVS (defined as > 20 PVS in the BG) were found in 42.6% of NVAF-IS patients vs. 8.4% of HTN-ICH ( p < 0.0001). Even after multivariate adjustment, the presence of NVAF remained significantly related to BG-PVS ( p = 0.001). Within the NVAF cohort, CHA2DS2-VASc was associated with the presence of severe BG-PVS ( p = 0.003) despite controlling for other covariates. When CHA2DS2-VASc was replaced with its individual components in the same regression model, congestive heart failure (CHF, p = 0.017), WMH burden ( p = 0.009), and age ( p = 0.02) were found to be predictors of severe BG-PVS.

Conclusions: Severe BG-PVS were significantly more common in NVAF patients compared to HTN-CSVD patients. NVAF-related features (CHA2DS2-VASc score) and CHF were associated with higher burdens of BG-PVS. These findings suggest that NVAF might play a role in the development of BG-PVS, conceivably through hemodynamic factors.

Abstract 19: Default Mode Network Alterations in Cerebral Amyloid Angiopathy: A Resting State FMRI Study

Introduction: Cerebral amyloid angiopathy (CAA) is an established cause of intracerebral hemorrhage and vascular dysfunction leading to ischemia. Functional connectivity analysis using MRI is becoming an important tool to analyze the brain activity during resting state, the default mode network (DMN) representing the prototypical set of connections. As CAA pathology has a posterior predominance, we sought to characterize the functional connectivity of the posterior DMN at resting state in patients with CAA.

Methods: Patients with probable CAA diagnosed using Boston Criteria and healthy controls (HC) were prospectively enrolled and received high resolution 3T MRI scans including dedicated resting-state fMRI sequences. Functional seed-to-seed analyses were done using the default processing pipeline in the CONN Toolbox. Correlation maps between the established DMN and specific regions of the posterior DMN, the precuneus and posterior cingulate, were averaged within groups and compared in an ANCOVA model.

Results: Study participants consisted of 60 patients with probable CAA and 20 healthy controls [aged 69 ± 7.5 vs 72.3 ± 8 years, P = 0.108]. Seed-to-seed analysis revealed a significantly lower strength of DMN connectivity in CAA when compared to controls in the precuneus [ P = 0.009] and posterior cingulate [ P = 0.003] adjusted for age and sex (Fig 1).

Conclusion: Patients with CAA exhibited significant loss of connectivity in the posterior regions of the DMN when compared to controls. The precuneus and posterior cingulate are core regions of the DMN with reportedly high metabolic rates at rest. Disruption of these posterior DMN regions might occur due to vascular amyloid pathology that shows a predominantly posterior distribution.

Abstract 103: Cortical tau Pathology in Cerebral Amyloid Angiopathy

Introduction: Cerebral amyloid angiopathy (CAA), a condition related to Alzheimer’s Disease, causes ischemic and hemorrhagic brain injury and contributes to cognitive impairment. Vascular amyloid, the hallmark of CAA, can be detected using amyloid PET imaging. We used selective tau imaging to understand the degree and associations of tau aggregation and deposition in patients with CAA.

Methods: Thirty-four patients with probable CAA but without cognitive impairment were prospectively enrolled. Selective tau imaging was performed using PET tracer flortaucipir (FTP) and amyloid imaging was obtained with Pittsburgh Compound B PET. Global and region of interest based (ROI) standardized uptake value ratios (SUVR) were calculated from PET acquisitions. High resolution multimodal MRIs were obtained for each patient and markers of CAA-related structural injury were quantified.

Results: The mean age ( + SD) of the patients was 69 + 6, 38% were female. Thirteen patients (38%) enrolled without intracerebral hemorrhage (ICH). Mean cortical FTP uptake was 1.18 + 0.11 (tau load, in SUVR). Five patients were tau positive based on FTP SUVR > 1.28 from a posterior cingulate cortex ROI, a previously validated method. Mean global cortical FTP uptake correlated with cortical amyloid load (r=0.37, p=0.04), centrum semiovale perivascular spaces (cs-PVS, r=0.49, p=0.004), extent of cortical superficial siderosis (cSS, r=0.44, p=0.01), and showed a trend for correlation with extent of leukoaraiosis (r=0.33, p=0.059). The associations with amyloid load and cs-PVS remained significant in multivariable models. Cortical FTP uptake was not associated with age, sex, vascular risk factors, presence of ICH or any of the CAA-related focal lesions (cerebral microbleeds, microinfarcts, lacunes), all p>0.2.

Conclusions: Our results show that many patients with CAA have some degree of cortical tau deposition, but severe tau positivity was not frequent (15%) in this cognitively normal CAA cohort, considering that 30% of healthy older adults were positive in other studies. The associations of cortical tau with brain amyloid and CAA-specific markers of global brain injury suggest that vascular amyloid might trigger tau deposition which, in turn, might increase parenchymal damage.

Abstract TP433: Structural, Molecular and Physiologic Alterations in Patients with Lobar Microbleeds

Background: Cerebral amyloid angiopathy (CAA) is diagnosed after a lobar intracerebral hemorrhage (L-ICH) but lobar microbleeds (LMB) are increasingly detected on MRIs of patients without L-ICH. We aimed to compare advanced imaging measures of structural brain damage, amyloid load, and cerebrovascular reactivity between CAA patients with L-ICH (CAA-ICH) and those with LMB (LMB-only).

Methods: Standard MRI markers (LMB counts, cortical superficial siderosis [cSS], enlarged perivascular spaces [EPVS], white matter hyperintensity [WMH] patterns) and FreeSurfer based advanced volumetric analyses (calculated as percent of total intracranial volume) were obtained in 115 non-demented patients with either CAA-ICH or LMB-only. Pittsburgh compound B PET measures of amyloid deposition and fMRI measures of vascular reactivity (amplitude, time-to-peak, time-to-baseline) were also compared between the 2 groups.

Results: LMB-only patients (n=37) presented with transient neurological symptoms or cognitive/gait complaints and stroke/neurodegenerative conditions were ruled out. Age, vascular risk factors, LMB counts, presence of cSS, EPVS counts and WMH patterns were not different between CAA-ICH and LMB-only (Table). Volume of WMH was significantly higher in CAA-ICH as compared to LMB-only patients in univariable and multivariable models (p=0.026). There was no difference in cortical thickness, WM volume, amyloid load/distribution and finally functional MRI markers of vascular reactivity between the two groups (Table).

Conclusions: Our results indicate that measures of vascular physiology and amyloid load as well as structural damage of LMB-only patients are not different from CAA-ICH, except a lower WMH load. These data support the view that LMB-only patients represent a non-hemorrhagic stage of the disease and that they can be enrolled in clinical trials aimed at modifying the molecular/physiologic changes to reverse/prevent CAA progression.

Coexistence of autoimmune diseases and autoantibodies in patients with myasthenia gravis

BACKGROUND

In this study, we assessed 75 patients with myasthenia gravis (MG) for coexistent autoimmune diseases (ADs) and for the characteristic autoantibodies that are associated with the most relevant forms of ADs.

METHODS

The demographic and clinical characteristics of the patients were recorded. In all patients, thyroid function tests, thyroid autoantibodies, and other autoantibodies were studied. The diagnosis of autoimmune thyroid disease (AITD) was made based on the clinical features, physical examination, and laboratory findings. The diagnoses of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) were made in accordance with the revised criteria of American College of Rheumatology. The presence of other ADs were also recorded which was based on whether or not the patient already had a diagnosis of ADs; or, whether it was detected during the period of the study based on clinical findings and/or laboratory abnormalities.

RESULTS

Thirty-nine patients (52%) had autoantibody positivity in their sera. Thyroid autoantibodies and antinuclear antibodies were the main autoantibodies detected. In twenty one of these patients, a diagnosis of AD could not be confirmed. Eighteen patients (24%) had a confirmed diagnosis of a coexisting AD. These ADs included AITD (16%), RA (4%), SLE (2.6%), and Lambert-Eaton myasthenic syndrome (1.3%). In ten patients, the diagnosis of ADs had been established before the development of MG; 8 of the patients included those who were newly diagnosed with ADs in the course of the management of MG.

CONCLUSIONS

MG has an increased frequency of coexisting ADs. Autoantibodies that are characteristic for ADs can be found in the patients without the presence of any of the clinical findings of ADs. Clinical attention towards the management of ADs is especially needed during the follow-up of patients with MG.

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.