Clopidogrel hyper-response increases peripheral hemorrhagic complications without increasing intracranial complications in endovascular aneurysm treatments requiring dual antiplatelet therapy

Clinical significance of increased clopidogrel response measured by VerifyNow P2Y12 assay is unclear; management guidelines are lacking in the context of neuroendovascular intervention. Our objective was to assess whether increased clopidogrel response predicts complications from endovascular aneurysm treatment requiring dual antiplatelet therapy. A single-institution, 9-year retrospective study of patients undergoing endovascular treatments for ruptured and unruptured aneurysms requiring aspirin and clopidogrel was conducted. Patients were grouped according to preoperative platelet inhibition in response to clopidogrel measured by the VerifyNow P2Y12 assay (VNP; P2Y12 reactivity units, PRU). Demographic and clinical features were compared across groups. Hemorrhagic complication rates (intracranial, major extracranial, minor extracranial) and thromboembolic complications (in-stent stenosis, stroke/transient ischemic attack) were compared, controlling for potential confounders and multiple comparisons. Data were collected from 284 patients across 317 procedures. Pre-operative VNP assays identified 9 % Extreme Responders (PRU ≤ 15), 13 % Hyper-Responders (PRU 16-60), 62 % Therapeutic Responders (PRU 61-214), 16 % Hypo-Responders (PRU ≥ 215). Increased response to clopidogrel was associated with increased risk of any hemorrhagic complication (≤60 PRU vs > 60 PRU; 39 % vs 24 %, P = 0.050); all intracranial hemorrhages occurred in patients with PRU > 60. Thromboembolic complications were similar between therapeutic and subtherapeutic patients (<215 PRU vs ≥ 215 PRU; 15 % vs 16 %, P = 0.835). Increased preoperative clopidogrel response is associated with increased rate of extracranial hemorrhagic complications in endovascular aneurysm treatments. Hyper-responders (16-60 PRU) and Extreme Responders (≤15 PRU) were not associated with intracranial hemorrhagic or thrombotic complications. Hypo-responders who underwent adjustment of antiplatelet therapy and neurointerventions did not experience higher rates of complications.

Association of Chronic Kidney Disease With Risk of Intracerebral Hemorrhage

Importance

The evidence linking chronic kidney disease (CKD) to spontaneous intracerebral hemorrhage (ICH) is inconclusive owing to possible confounding by comorbidities that frequently coexist in patients with these 2 diseases.

Objective

To determine whether there is an association between CKD and ICH risk.

Design, Setting, and Participants

A 3-stage study that combined observational and genetic analyses was conducted. First, the association between CKD and ICH risk was tested in the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study, a multicenter case-control study in the US. All participants with available data on CKD from ERICH were included. Second, this analysis was replicated in the UK Biobank (UKB), an ongoing population study in the UK. All participants in the UKB were included in this study. Third, mendelian randomization analyses were implemented in the UKB using 27 CKD-related genetic variants to test for genetic associations. ERICH was conducted from August 1, 2010, to August 1, 2017, and observed participants for 1 year. The UKB enrolled participants between 2006 and 2010 and will continue to observe them for 30 years. Data analysis was performed from November 11, 2019, to May 10, 2022.

Exposures

CKD stages 1 to 5.

Main Outcomes and Measures

The outcome of interest was ICH, ascertained in ERICH via expert review of neuroimages and in the UKB via a combination of self-reported data and International Statistical Classification of Diseases, Tenth Revision, codes.

Results

In the ERICH study, a total of 2914 participants with ICH and 2954 controls who had available data on CKD were evaluated (mean [SD] age, 61.6 [14.0] years; 2433 female participants [41.5%]; 3435 male participants [58.5%]); CKD was found to be independently associated with higher risk of ICH (odds ratio [OR], 1.95; 95% CI, 1.35-2.89; P < .001). This association was not modified by race and ethnicity. Replication in the UKB with 1341 participants with ICH and 501 195 controls (mean [SD] age, 56.5 [8.1] years; 273 402 female participants [54.4%]; 229 134 male participants [45.6%]) confirmed this association (OR, 1.28; 95% CI, 1.01-1.62; P = .04). Mendelian randomization analyses indicated that genetically determined CKD was associated with ICH risk (OR, 1.56; 95% CI, 1.13-2.16; P = .007).

Conclusions and Relevance

In this 3-stage study that combined observational and genetic analyses among study participants enrolled in 2 large observational studies with different characteristics and study designs, CKD was consistently associated with higher risk of ICH. Mendelian randomization analyses suggest that this association was causal. Further studies are needed to identify the specific biological pathways that mediate this association.

Abstract 105: Polygenic Burden Of Hypertension-related Alleles Leads To Non-traumatic Subarachnoid Hemorrhage At Younger Ages

Introduction: Non-traumatic subarachnoid hemorrhage (SAH) is strongly linked to hypertension, a condition highly influenced by common genetic variants. For complex diseases influenced by genetic and environmental factors, genetic predisposition plays a key role in earlier onset. We tested the hypothesis that persons with a higher polygenic burden of hypertension-related alleles have SAH at younger ages.

Methods: We analyzed data from the UK Biobank, a large cohort study that enrolled over 500,000 Britons aged 40-69. We included participants of European descent. We constructed two polygenic risk scores (PRS) using 807 independent genetic variants known to associate with higher systolic and diastolic blood pressure (BP). We fitted linear regression to assess the relationship between these PRS and the age-of-onset of SAH, using product terms to test for interaction with sex. We subsequently implemented Mendelian Randomization analyses using the inverse variance weighted and weighted median methods to evaluate causality.

Results: We evaluated a total of 1,178 SAH cases (mean age, 58; female sex, 722 [61.3%]). When evaluating all participants jointly, there was no association between the systolic BP PRS and age-of-onset for SAH (p=0.130). There was a significant interaction between the PRS and sex (p=0.002): each additional standard deviation of the systolic BP PRS was associated with an earlier onset of SAH in females (beta, -1.45; 95% CI, -2.31 to -0.58; p=0.001), but not in males (adjusted beta, 0.83; 95% CI, -0.37 to 2.02; p=0.176). In MR analyses, a 10mmHg increase in genetically determined systolic BP was associated with a 5-year earlier onset of SAH in female participants using both the inverse variance weighted (beta, -4.72; 95% CI, -7.34 to -2.10; p<0.001) and weighted median approaches (beta, -5.05; 95% CI, -9.19 to -0.90; p=0.017). Analyses with the diastolic BP SNPs yielded comparable results (all p<0.05).

Conclusions: Genetically determined hypertension is associated with earlier onset of non-traumatic SAH in women. These results indicate that genetic predisposition may play a more important causal role in younger patients and point to genetic information as possible tools for early identification of high-risk individuals.

Abstract WP191: Genetic Analyses Support A Causal Role Of Lung Cancer In Ischemic Stroke

Introduction: Lung cancer has been linked to increased risk of thromboembolic events, including stroke. However, a causal relationship between lung cancer and ischemic stroke (IS) has yet to be established.

Methods: We conducted a two-stage study using observational and genetic data from the UK Biobank, a large cohort study that enrolled over 500,000 Britons aged 40-69. We included participants of European descent. In Stage I, we used logistic regression to test the association between self-reported / ICD-defined lung cancer and risk of IS. In Stage II, we constructed a polygenic risk score (PRS) using 31 independent genetic variants known to associate with lung cancer, fitted logistic regression to assess the relationship between this PRS and risk of IS, and implemented the inverse variance weighted method of Mendelian randomization (MR). We tested for horizontal pleiotropy using the MR-Egger and MR Pleiotropy Residual Sum and Outlier (MR-PRESSO) approaches.

Results: Out of 409,629 participants of European descent enrolled in the UK Biobank, there were 5,060 IS cases (mean age, 61.6 [standard deviation 6.5]; female sex, 1813 [35.8%]). The prevalence of lung cancer was 1.9% (n=94) and 0.5% (n=1,961) among persons with and without IS, respectively (unadjusted p<0.001). In multivariable analyses, self-reported / ICD-defined lung cancer was associated with a 54% increase in risk of IS (adjusted OR, 1.54; 95% CI, 1.30-1.81; p<0.001). Genetic analyses supported a causal link between lung cancer and IS. In PRS analysis, each additional standard deviation of the lung cancer-related PRS was associated with a 3% increase in risk of IS (adjusted OR, 1.03; 95% CI, 1.01-1.06; p=0.018). In MR analysis, genetically determined lung cancer was associated with a 5% increase in risk of IS (OR, 1.05; 95% CI, 1.01-1.09; p=0.022). There was no significant horizontal pleiotropy (MR-Egger intercept p=0.663; MR-PRESSO global test p=0.993).

Conclusions: Genetically determined lung cancer is associated with increased risk of ischemic stroke. These findings provide evidence for a causal link between lung cancer and ischemic stroke. Further studies are needed to identify the biological pathways that mediate this link.

Nickels and tines: the myth of nickel allergy in intracranial stents

BACKGROUND

Most intracranial stents contain nickel alloy, and nickel allergy or hypersensitivity is common. Neurological injury following endovascular treatment with a nickel containing intracranial stent has been reported in patients with purported nickel allergy, but it is unclear whether these reactions represent true nickel hypersensitivity. We quantified nickel release from commonly used intracranial stents to investigate whether such stents should be avoided in patients with nickel allergy.

METHODS

We examined nickel release from seven commonly used intracranial stents: Enterprise, LVIS Jr, Neuroform, Wingspan, Zilver, Pipeline Flex Embolization Device, and Surpass Evolve. We incubated each stent in human plasma-like media for 30 days. Dimethylglyoxime (DMG) spot testing was performed on each stent to detect released nickel at 0 and 30 days. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was then used to quantify the nickel concentration of the media at 30 days. Nickel currency and nickel standard for atomic absorption spectrometry were used as positive controls.

RESULTS

DMG spot tests indicated nickel release only from nickel currency at 0 and 30 days of incubation. No nickel release was detected from any stent at 30 days using ICP-OES.

CONCLUSIONS

Nickel release from commonly used intracranial stents is negligible. These results suggest that previously reported hypersensitivity to these stents may be misattributed to nickel allergy, and that patients with nickel allergy may be safely treated with select nickel-containing stents.

Severe, Intolerable Fatigue Associated with Hyperresponse to Clopidogrel

OBJECTIVE

Clopidogrel is a commonly used antiplatelet agent for the prevention of thromboembolic complications following neuroendovascular procedures, but anecdotal data have raised concern for the possibility that clopidogrel may induce severe, intolerable fatigue. The purpose of this study is to systematically investigate this phenomenon.

METHODS

We performed a dual-institution, 9-year, retrospective study of patients undergoing clopidogrel therapy for neuroendovascular procedures. Patients were included only if their response to clopidogrel was assessed by platelet function testing using the VerifyNow P2Y₁₂ (VNP) assay. Hyperresponse to clopidogrel was defined as P2Y₁₂ reaction units ≤60. Patients were considered to have had clopidogrel-induced severe fatigue if the onset of symptoms followed the initiation of clopidogrel therapy; symptoms improved following a reduction in the dose of clopidogrel; and symptoms could not be attributed to any other medical explanation.

RESULTS

Data were collected on 349 patients. Five patients (1.4%) met criteria for clopidogrel-induced severe fatigue. All 5 patients were female, ages 39-68. VNP assessments obtained while patients were symptomatic revealed hyperresponse to clopidogrel (0-22 P2Y₁₂ reaction units). Symptoms improved in all 5 patients when the dose of clopidogrel was reduced by half. Notably, 30% of patients (n = 103) demonstrated a hyperresponse to clopidogrel on at least 1 VNP assessment, but 98 of these patients did not suffer from severe fatigue.

CONCLUSIONS

A syndrome of severe fatigue and other constitutional symptoms is a rare but clinically significant side effect of hyperresponse to clopidogrel in patients undergoing neuroendovasular intervention.

Obstructive Sleep Apnea as a Risk Factor for Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

To determine whether obstructive sleep apnea (OSA) is associated with intracerebral hemorrhage (ICH) risk, we assessed premorbid OSA exposure of patients with nontraumatic ICH and matched controls.

METHODS

Ethnic/Racial Variations of Intracerebral Hemorrhage is a multicenter, case-control study evaluating risk factors for ICH that recruited 3000 cases with ICH and 3000 controls. OSA status was ascertained using the Berlin Questionnaire as a surrogate for premorbid OSA. We performed logistic regression analyses to evaluate the association between OSA and ICH.

RESULTS

Two thousand and sixty-four (71%) cases and 1516 (52%) controls were classified as having OSA by the Berlin Questionnaire. Cases with OSA were significantly more likely to be male and have hypertension, heart disease, hyperlipidemia, and higher body mass index compared with those without OSA. OSA was more common among cases compared with controls (71% versus 52%, odds ratio, 2.28 [95% CI, 2.05-2.55]). In a multivariable logistic regression model, OSA was associated with increased risk for ICH (odds ratio, 1.47 [95% CI, 1.29-1.67]).

CONCLUSIONS

OSA is a risk factor for ICH.

Association of Serum IL-6 (Interleukin 6) With Functional Outcome After Intracerebral Hemorrhage

BACKGROUND AND OBJECTIVES

IL-6 (interleukin 6) is a proinflammatory cytokine and an established biomarker in acute brain injury. We sought to determine whether admission IL-6 levels are associated with severity and functional outcome after spontaneous intracerebral hemorrhage (ICH).

METHODS

We performed an exploratory analysis of the recombinant activated FAST trial (Factor VII for Acute ICH). Patients with admission serum IL-6 levels were included. Regression analyses were used to assess the associations between IL-6 and 90-day modified Rankin Scale. In secondary analyses, we used linear regression to evaluate the association between IL-6 and baseline ICH and perihematomal edema volumes.

RESULTS

Of 841 enrolled patients, we included 552 (66%) with available admission IL-6 levels (mean age 64 [SD 13], female sex 203 [37%]). IL-6 was associated with poor outcome (modified Rankin Scale, 4-6; per additional 1 ng/L, odds ratio, 1.30 [95% CI, 1.04-1.63]; P=0.02) after adjustment for known predictors of outcome after ICH and treatment group. IL-6 was associated with ICH volume after adjustment for age, sex, and ICH location, and this association was modified by location (multivariable interaction, P=0.002), with a stronger association seen in lobar (β, 12.51 [95% CI, 6.47-18.55], P<0.001) versus nonlobar (β 5.32 [95% CI, 3.36-7.28], P<0.001) location. IL-6 was associated with perihematomal edema volume after adjustment for age, sex, ICH volume, and ICH location (β 1.22 [95% CI, 0.15-2.29], P=0.03). Treatment group was not associated with IL-6 levels or outcome.

CONCLUSIONS

In the FAST trial population, higher admission IL-6 levels were associated with worse 90-day functional outcome and larger ICH and perihematomal edema volumes.

Abstract P410: Association of Serum GFAP With Hematoma Expansion and Poor Outcome After Intracerebral Hemorrhage: The Factor VII for ICH Trial

Background: Biomarkers may help identify patients most likely to benefit from therapies. We tested whether serum glial fibrillary acidic protein (GFAP), a biomarker elevated early after intracerebral hemorrhage (ICH) in response to blood-brain barrier disruption, is associated with hematoma expansion (HE) and outcome after ICH and whether GFAP levels modify the effect of factor VII treatment.

Methods: We performed an exploratory analysis of the recombinant activated factor VII for acute ICH (FAST) trial. FAST collected serum GFAP levels were collected at admission within 4 hours of ICH onset prior to factor VII treatment. We used regression analyses to evaluate the associations between serum GFAP, HE (dichotomized as &gte; 33% or &gt; 6 mL increase in ICH volume from baseline to 24h and as the absolute volume of expansion), and 3-month poor outcome (modified Rankin Scale score 4-6). We tested for interaction between GFAP and factor VII treatment by adding product terms to multivariable regression models.

Results: Of 841 enrolled patients, we included 567 (67%) with available GFAP levels (mean age 64 [SD 13], female sex 203 [37%]). GFAP was associated with HE (adjusted odds ratio [OR] 1.54, 95% CI 1.10-2.17) and poor outcome (adjusted OR 1.86, 95% CI 1.18-3.09). Compared to patients in the lowest GFAP quartile, those in the highest quartile had 2 times the odds of HE (95% CI 1.08-3.89) and 2.7 times the odds of a poor outcome (95% CI 1.33-5.70). GFAP modified the association between factor VII treatment and HE volume (multivariable interaction p=0.04): treatment was not associated with reduced HE volume in the lowest GFAP quartile (β -0.44, 95% CI -3.54 to 2.67), but was associated with reduced HE volume in higher quartiles (β -3.82, 95% CI -7.58 to -0.06).

Conclusions: In the FAST trial population, early GFAP levels were associated with HE and poor functional outcome. Factor VII treatment was associated with a greater reduction in HE volume in patients with higher GFAP levels. Serum GFAP may be useful for risk-stratifying patients early after ICH onset.

Abstract MP13: Polygenic Susceptibility to Atrial Fibrillation is Associated With Silent Cerebrovascular Disease in Stroke-Free Persons Without Atrial Fibrillation

Introduction: Clinically silent cerebrovascular disease is present in 40% of persons over the age of 60. We hypothesize that polygenic susceptibility to atrial fibrillation is associated with the burden of white matter disease in persons without atrial fibrillation or history of ischemic stroke.

Methods: We conducted a nested genetic and neuroimaging study within the UK Biobank, a large cohort study that enrolled community dwelling Britons aged 40 to 65 at recruitment. We used data on a subcohort of patients evaluated with brain MRIs. The volume of white matter hyperintensities (WMH) was estimated using the BIANCA lesion segmentation tool. Genomic data was ascertained via genotyping with the Affymetrix UK Biobank Axiom array followed by imputation with 1000 Genomes reference panels. To model the polygenic susceptibility to atrial fibrillation (AFIB), we constructed a polygenic risk score (PRS) using 957 independent genetic risk variants known to significantly associate with atrial fibrillation. We used logistic and linear regression to test for association between the PRS and WMH.

Results: A total of 38,914 study participants underwent brain MRI imaging in the UK Biobank. Of these, we excluded 124 (0.3%) with a history of stroke and 926 (2.4%) with AFIB. 37,864 study participants were included in this study, of which 19,059 (50.3%) had WMH. High genetic risk of AFIB was not associated with no-versus-any WMH (p=0.51). When evaluating persons with WMH lesions, high genetic risk of AFIB was associated with higher WMH volume (per 1 SD increase of the PRS, beta 0.019, SE 0.006; p=0.01). Gender was an important effect modifier of this association (interaction p=0.03): while high genetic risk of AFIB was associated with a significant increase in WMH volume in females (per 1 SD increase of the PRS, beta 0.03, SE 0.008; p<0.001), no association was found for males (p=0.99).

Conclusions: Polygenic susceptibility to atrial fibrillation is associated with more severe silent cerebrovascular disease in persons without atrial fibrillation. Further research should evaluate whether this genetic information can be used to identify persons for tailored diagnostic or therapeutic interventions.

Time-dynamic pulse modulation of spinal cord stimulation reduces mechanical hypersensitivity and spontaneous pain in rats

Enhancing the efficacy of spinal cord stimulation (SCS) is needed to alleviate the burden of chronic pain and dependence on opioids. Present SCS therapies are characterized by the delivery of constant stimulation in the form of trains of tonic pulses (TPs). We tested the hypothesis that modulated SCS using novel time-dynamic pulses (TDPs) leads to improved analgesia and compared the effects of SCS using conventional TPs and a collection of TDPs in a rat model of neuropathic pain according to a longitudinal, double-blind, and crossover design. We tested the effects of the following SCS patterns on paw withdrawal threshold and resting state EEG theta power as a biomarker of spontaneous pain: Tonic (conventional), amplitude modulation, pulse width modulation, sinusoidal rate modulation, and stochastic rate modulation. Results demonstrated that under the parameter settings tested in this study, all tested patterns except pulse width modulation, significantly reversed mechanical hypersensitivity, with stochastic rate modulation achieving the highest efficacy, followed by the sinusoidal rate modulation. The anti-nociceptive effects of sinusoidal rate modulation on EEG outlasted SCS duration on the behavioral and EEG levels. These results suggest that TDP modulation may improve clinical outcomes by reducing pain intensity and possibly improving the sensory experience.

Automated and rapid self-report of nociception in transgenic mice

There are currently no rapid, operant pain behaviors in rodents that use a self-report to directly engage higher-order brain circuitry. We have developed a pain detection assay consisting of a lick behavior in response to optogenetic activation of predominantly nociceptive peripheral afferent nerve fibers in head-restrained transgenic mice expressing ChR2 in TRPV1 containing neurons. TRPV1-ChR2-EYFP mice (n = 5) were trained to provide lick reports to the detection of light-evoked nociceptive stimulation to the hind paw. Using simultaneous video recording, we demonstrate that the learned lick behavior may prove more pertinent in investigating brain driven pain processes than the reflex behavior. Within sessions, the response bias of transgenic mice changed with respect to lick behavior but not reflex behavior. Furthermore, response similarity between the lick and reflex behaviors diverged near perceptual threshold. Our nociceptive lick-report detection assay will enable a host of investigations into the millisecond, single cell, neural dynamics underlying pain processing in the central nervous system of awake behaving animals.

Abstract WP214: Risk Factors for Recurrence of Vascular Events in Middle-Aged Stroke Survivors

Background: Stroke in middle-aged persons is emerging as a distinct entity from previously described "stroke in the young.” Risk factors for recurrence of vascular events in middle-aged stroke survivors have not been well described in a large, racially diverse US-based population.

Methods: We performed a retrospective longitudinal analysis of claims data from all hospitalizations in California (2005-2011), Florida (2005-2014), and New York (2005-2014). We included survivors of first-ever ischemic stroke (IS) and non-traumatic intracerebral hemorrhage (ICH). We used validated ICD-9 codes to identify recurrent vascular events, defined as a readmission with a primary diagnosis of IS, ICH, or myocardial infarction (MI). We used survival analysis and Cox proportional hazards regression to determine factors associated with recurrence risk in middle-aged (40-60 years) versus older (>60 years) adults.

Results: We identified 123,212 non-fatal hospitalizations for first-ever IS or ICH in middle-aged adults. There were 14,721 readmissions for recurrent vascular events (11.9%) over a mean follow-up of 4.0 years (standard deviation [SD] 2.8 years). The 1-year and 10-year recurrence rates were 5.5% (95% confidence interval [CI], 5.3%-5.6%) and 19.4% (95% CI, 19.0%-19.8%) respectively. In multivariable analysis, black (hazard ratio [HR] 1.44; 95% CI, 1.39-1.50; p<0.001) and Hispanic race (HR 1.10; 95% CI, 1.05-1.16; p<0.001), diabetes (HR 1.76; 95% CI, 1.70-1.82; p<0.001), smoking (HR 1.22; 95% CI, 1.18-1.27; p<0.001), hyperlipidemia (HR 1.08; 95% CI, 1.04-1.12; p<0.001), and hypertension (HR 1.06; 95% CI, 1.03-1.10; p<0.001) were associated with increased risk. The associations of black race and diabetes were modified by age category (both multivariable interactions p<0.001). Black race and diabetes were associated with greater increases in risk in middle-aged versus older adults (in older adults: black race HR 1.28; 95% CI, 1.25-1.31; p<0.001; diabetes HR 1.27; 95% CI, 1.25-1.30; p<0.001).

Conclusions: Black race and diabetes were the strongest risk factors for recurrence of vascular events in a middle-aged population. Further study of interventions to reduce recurrence and resulting disability in this younger, higher risk population is needed.

Abstract WP400: Causes of Death in a Longitudinal Analysis of Spontaneous Intracerebral Hemorrhage Survivors

Introduction: With improvements in acute care, more patients are surviving a first-time spontaneous intracerebral hemorrhage (ICH). In the growing survivor population, little is known about effective secondary stroke prevention strategies or long-term causes of illness and death. This study aims to determine the cause of death in first-time ICH survivors.

Methods: We performed a longitudinal analysis of prospectively collected claims data. We used data collected on all hospitalizations from California (2005-2011) and New York (2005-2014). State residents admitted with a primary diagnosis of non-traumatic ICH (ICD-9-CM code 431) who survived to discharge were included in the study. Patients were followed for a primary outcome of any readmission event resulting in death. Cause of death was defined as the primary diagnosis assigned at discharge. Kaplan-Meier survival analysis was used to estimate the risk of in-hospital death during follow-up. Cox proportional hazards and multinomial logistic regression were used to determine factors associated with the risk and cause for death. Subgroup analyses stratified by a history of atrial fibrillation (AF) were performed.

Results: Of 56,593 identified ICH survivors (mean age 69 [SD 15], 49% female), 6,931 (14%) died during a median follow-up period of 3.6 years (IQR 1.5-5.9). The one-year risk of death was 7% (95% CI 7.0-7.4) and the median time to death was 0.7 years (IQR 0.1-2.3). Patients who died were older (74 vs. 68, p<0.001) and more likely to have history of AF (24% vs. 16%, p<0.001), congestive heart disease (15% vs. 8%, p<0.001), and diabetes (32% vs. 26%, p<0.001). The leading causes of death were infection (29%), recurrent ICH (12%), cardiac causes (8%), respiratory failure (7%), and ischemic stroke (4%). Patients with AF were at an increased the risk of death from ischemic stroke (OR 2.04, 95% CI 1.56-2.68, p<0.001) and cardiac causes (OR 1.49, 95% CI 1.19-1.87, p=0.002) compared to those without AF.

Conclusions: The leading causes of inpatient death in ICH survivors are infection, recurrent ICH, and cardiac causes while survivors with AF are at an elevated risk for death by recurrent stroke. These findings may represent interventional targets in the effort to extend improved outcomes in ICH survivors.

Abstract TP347: Obstructive Sleep Apnea Frequency in Intracerebral Hemorrhage

Introduction: Obstructive sleep apnea (OSA) is a treatable condition and well-established risk factor for ischemic stroke, but the prevalence in ICH is unknown. We aim to characterize the frequency of OSA in spontaneous intracerebral hemorrhage (ICH).

Methods: The Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study is a prospective observational study evaluating risk factors for ICH among whites, blacks, and Hispanics. OSA status was determined using two different strategies: (1) the Berlin Questionnaire, a validated screening tool to identify those with a high likelihood of OSA where “high risk” is defined as > 1 point in at least 2 of 3 categories assessing snoring, fatigue, and hypertension, and (2) self-reported history of diagnosed sleep apnea.

Results: We evaluated 3000 ICH cases. Within this group, 2896 (96.5%) completed the Berlin questionnaire, with 2064 (71%) patients being high risk for OSA. Compared to patients with low risk of OSA, those at high risk were more likely to be male (61% versus 53%, p<0.001) with hypertension (93% versus 65%, p<0.001), diabetes (32% versus 20%, p<0.001), hyperlipidemia (49% versus 38%, p<0.001), and higher BMI (29.8 +/- 8.1 versus 26.8 +/- 6.5, p<0.001), and less likely to have lobar ICH location (29% versus 35%, p<0.001). Self-reported history of prior sleep apnea diagnosis was present in only 175 (9.5%) of ICH cases.

Conclusions: OSA is highly prevalent and underdiagnosed in our cohort of ICH patients. Given the effective treatments available for OSA, which have been shown to improve morbidity and mortality in patients with ischemic stroke, further studies are needed to assess the role of OSA as both a determinant of both risk and outcome in ICH.

Abstract 66: Causal Associations Between Genetically-determined Smoking and Risk of Subarachnoid Hemorrhage

Introduction: Animal and observational studies indicate that smoking is a risk factor for aneurysm formation and rupture, leading to subarachnoid hemorrhage (SAH). However, a definitive causal relationship between smoking and SAH has not been established. We leveraged the causal properties of mutation-disease associations to test the hypothesis that smoking is causally linked to SAH.

Methods: We conducted a one-sample Mendelian Randomization (MR) study within the UK Biobank, a prospective, population-based observational study. We restricted the analysis to study participants with genetically-confirmed European ancestry. SAH cases were ascertained using previously validated codes. As the instrument, we built a polygenic risk score (PRS) using independent (R2<0.1) genetic variants known to be associated (p<5x10-8) with smoking. For the primary MR analysis, we implemented the ratio method using the estimates obtained from testing the PRS for association with risk of SAH and smoking. In secondary analyses, we implemented the inverse-variance weighted (IVW) and weighted median (WM) methods. Pleiotropy was assessed via the MR-Egger approach.

Results: We included a total of 408,622 individuals in this study (mean age 57 [SD 8], female sex 220,944 [54%]). Of these, 132,568 (32%) ever smoked regularly and 904 (0.22%) had an SAH. Each additional standard deviation of the smoking PRS was associated with a 9% increased risk of SAH (OR 1.09, 95%CI 1.03-1.17; p=0.006) and 21% increased risk of smoking (OR 1.21, 95%CI 1.2-1.21; p=1x10-16). In the primary analysis, genetically-determined smoking was associated with a 63% increase in risk of SAH (OR 1.63, 95%CI 1.15-2.30; p=0.006). Secondary analyses using the IVW method (OR 1.57, 95%CI 1.13-2.17; p=0.007) and the WM method (OR 1.74, 95%CI 1.06-2.86; p=0.028) yielded comparable results. There was no significant pleiotropy (MR-Egger intercept p=0.38).

Conclusion: Genetically-determined smoking is strongly associated with the risk of SAH. These findings provide evidence for a causal link between smoking and the occurrence of this often-debilitating condition. Interventions aimed at reducing smoking behavior could offer significant benefits, especially to those at high risk of SAH.

Abstract 71: Sex and Genetic Predisposition Synergistically Influence Risk of Stroke and Myocardial Infarction in Middle-Aged Persons Without Risk Factors

Background and Hypothesis: Driven by aging-related physiological changes, the incidence of stroke and myocardial infarction rises rapidly in persons aged >40 years. A significant proportion of these acute vascular events (AVE) take place in persons without vascular risk factors. We tested the hypothesis that sex and genetic predisposition synergistically increase the risk of AVE in middle-aged persons without vascular risk factors.

Methods: We analyzed data from the UK Biobank, a prospective longitudinal study that enrolled persons aged 40 to 69 years. Our analysis was restricted to middle-aged participants, defined as those aged 40 to 60 years. Prevalent and incident cases of stroke (ischemic and hemorrhagic) and myocardial infarction were included. To quantify the genetic predisposition to sustain an AVE, we constructed a polygenic risk score using 68 independent (R 2 <0.1) genetic variants known to associate (p<5x10 -8 ) with AVE. Participants were classified as having low, intermediate or high genetic risk according to tertiles of the score. We used Cox models for association and interaction testing.

Results: Of the 502,536 study participants enrolled in the UK Biobank, 303,295 (60%) did not have any vascular risk factors. During the follow-up period, there were 5,746 AVEs, including 1,954 strokes and 3,792 myocardial infarctions. The cumulative risk of AVE was 0.12% (n=352), 0.46% (n = 1,386) and 1.32% (n = 4,008) at ages 40, 50 and 60 years (test-for-trend p<0.001). The risk of AVE was 3 times greater in men than women (HR 3.30, 95%CI 3.08 - 3.53). Compared to persons with low genetic risk, those with intermediate and high genetic risk had a 22% (HR 1.22, 95%CI 1.13 - 1.32) and 52% (HR 1.52, 95%CI 1.41 - 1.65) increase in risk of AVE, respectively. There was significant synergy (interaction) between sex and genetic predisposition: compared to females with low genetic risk, males with high genetic risk had 4 times (HR 3.91, 95%CI 3.58 - 4.26) the risk of AVE (interaction analysis p<0.001).

Conclusion: Genetic information constitutes a promising tool to risk stratify middle-aged persons without vascular risk factors. The synergistic effect of sex and genetic predisposition points to specific subgroups that could benefit from aggressive preventive interventions.