[Show abstract][Hide abstract] ABSTRACT: Objective – The effect of pre-stroke aspirin use on initial severity, hemorrhagic transformation and functional outcome of ischemic stroke is uncertain. Methods - Using a multicenter stroke registry database, patients with acute ischemic stroke of 3 subtypes [large artery atherosclerosis (LAA), small vessel occlusion (SVO) or cardioembolism (CE)] were identified. NIH stroke scale (NIHSS) and hemorrhagic transformation at presentation and discharge modified Rankin scale (mRS) were compared between pre-stroke aspirin users and non-users. Results - Among the 10,433 patients, 1,914 (18.3%) patients reported pre-stroke aspirin use. On crude analysis, initial NIHSS scores of aspirin users were higher than non-users [mean difference 0.35; 95% confidence interval (CI), 0.04 to 0.66]. However, a multivariable analysis with an application of inverse probability of treatment weighting based on a propensity score of pre-stroke aspirin, having an interaction effect of pre-stroke aspirin use and stroke subtype in the model, showed less stroke severity for aspirin users in LAA but not in SVO and CE than for non-users; mean difference in NIHSS scores in LAA was -0.97 (95% CI, -1.45 to -0.49). With respect to hemorrhagic transformation and mRS, no significant interaction effects were found. Pre-stroke aspirin use increased the risk of hemorrhagic transformation (adjusted odd ratio, 1.34; 95% CI, 1.05 to 1.73) but decreased the odds of the higher discharge mRS (0.86; 0.76 to 0.96). Interpretation - Pre-stroke aspirin use may reduce initial stroke severity in atherothrombotic stroke and can improve functional outcome at discharge despite an increase of hemorrhagic transformation irrespective of stroke subtype. This article is protected by copyright. All rights reserved.
Full-text · Article · Jan 2016 · Annals of Neurology
[Show abstract][Hide abstract] ABSTRACT: We aimed to examine whether direct access to hospitals offering intravenous thrombolysis is associated with functional outcomes in patients with acute ischemic stroke treated with intravenous thrombolysis. We enrolled patients who received intravenous thrombolysis within 4.5. hours of symptom onset using a prospective multicenter registry database. Patients referred directly from the field to organized stroke centers were compared with those who were transferred from non-thrombolysis-capable hospitals in terms of clinical outcomes at 90. days after intravenous recombinant tissue plasminogen activator treatment. We also investigated onset-to-door time and onset-to-needle time according to admission mode. A total of 820 patients (mean age of 67.3. years and median National Institutes of Health Stroke Scale score of 9) were enrolled. Seventeen percent of patients with AIS who received intravenous thrombolytic therapy at 12 hospitals (n = 142) were transferred from other hospitals. The direct admission group had a shorter median onset-to-admission time (63 versus 121. minutes, P <. 0.001) and onset-to-needle time (110 versus 161. minutes, P <. 0.001) as compared with the indirect admission group. Direct admission was associated with a good outcome with an odds ratio of 1.57 (95% confidence interval: 1.02-2.39, P = 0.036) after adjustment for baseline variables. Direct admission to a hospital with intravenous thrombolysis facilities available at all times was associated with shorter onset-to-needle time and better outcome in patients with AIS undergoing thrombolytic therapy. Our findings support the implementation of regional stroke care programs transporting patients directly to stroke centers to promote faster treatment and to achieve better outcomes.
Full-text · Article · Jan 2016 · Journal of Clinical Neuroscience
[Show abstract][Hide abstract] ABSTRACT: High residual platelet activation (HRPA) after ADP stimuli has associated with recurrent vascular events in acute atherothrombosis with the use of antiplatelet agents (APAs). However, there has been little evidence supporting this association in acute ischemic stroke (AIS). In this study, we evaluated the influences of HRPR after ADP stimuli on the 1-year incidence of recurrent cardiovascular events and mortality in AIS with APAs. We conducted an observational, referral center cohort study on 968 AIS patients with APAs from January 2010 to December 2013 who were evaluated using optical platelet aggregometry (OPA). All patients received the dual APA combination of aspirin and clopidogrel or aspirin alone. We evaluated their platelet function 5 days after hospital admission using OPA. HRPR after ADP stimuli was defined as platelet aggregation of 70 % or greater according to OPA after 10 µM ADP stimuli. The primary endpoint was a composite of all causes of death, myocardial infarction, and stroke at the 1-year follow-up. The secondary endpoints were each component of the primary endpoint. The event rate of primary endpoint was 11.3 % (109/968). Its rate was significantly higher in the patients with HRPR (16.7 %) than in those without (9.7 %). HPRP was independently associated with the primary endpoint (OR = 1.97, CI 1.22-3.18, p < 0.01). According to the AIS subtype, the presence of HRPR was independently significant for the occurrence of the primary endpoint in the large artery atherosclerosis (LAA) subtype only (OR = 2.26, CI 1.15-4.45, p = 0.02). In this study, the presence of HRPR after ADP stimuli is associated with a poor long-term outcome after acute ischemic stroke. In particular, the influence of this factor might be more prominent in LAA compared with other types of AIS.
No preview · Article · Dec 2015 · Journal of Thrombosis and Thrombolysis
[Show abstract][Hide abstract] ABSTRACT: Background:
Patients with acute ischemic stroke (AIS) are at high risk of subsequent vascular events. The aim of this study was to estimate rates of recurrent stroke, myocardial infarction (MI), and major vascular events during the first year after AIS in Korea.
Through a multicenter stroke registry in Korea, 12,227 consecutive cases of AIS were identified between November 2010 and May 2013 and were followed up for recurrent stroke, MI, and major vascular events up to 1 year after stroke.
Cumulative 30-day, 90-day and 1-year rates were 2.7%, 3.9%, and 5.7% for recurrent stroke; .1%, .3%, and .5% for MI; and 8.1%, 10.6%, and 13.7% for major vascular events, indicating that the early period is at high risk of recurrent stroke and major vascular events. The risk of recurrent stroke was substantially higher than the risk of MI: 13.0 times at 90 days and 11.4 times at 1 year. Compared to those with small-vessel occlusion (SVO), those with ischemic stroke subtypes other than SVO had a higher risk of recurrent stroke as well as major vascular events. Other common independent predictors for recurrent stroke and major vascular events were diabetes and prior stroke history.
During the first year after AIS, one in 18 had recurrent stroke and one in 7 major vascular events. More than two thirds of recurrent stroke and three quarters of major vascular events developed within 90 days in a Korean cohort of stroke patients. Better prevention strategies are required for high-risk patients during this high-risk period.
Full-text · Article · Dec 2015 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
[Show abstract][Hide abstract] ABSTRACT: Background and purpose:
In a recent pooled analysis of randomized clinical trials (RCTs), intravenous tissue plasminogen activator (TPA) improves the outcome in patients aged ≥80 years. However, it is uncertain whether the findings are applicable to clinical practice in Asian populations.
From a multicenter stroke registry database of Korea, we identified patients with acute ischemic stroke who were aged ≥ 80 years. Using multivariable analysis and propensity score (PS)-matched analyses, we assessed the effectiveness and safety of intravenous TPA within 4.5 hours.
Among 2,334 patients who met the eligible criteria, 236 were treated with intravenous TPA (mean age, 83±5; median NIHSS, 13 [IQR, 8-17]). At discharge, the TPA group compared to the no-TPA group had a favorable shift on the modified Rankin Scale (mRS) score (multivariable analysis, OR [95% CI], 1.51 [1.17-1.96], P=0.002; PS-matched analysis, 1.54 [1.17-2.04], P=0.002) and was more likely to achieve mRS 0-1 outcome (multivariable analysis, 2.00 [1.32-3.03], P=0.001; PS-matched analysis, 1.59 [1.04-2.42], P=0.032). TPA treatment was associated with an increased risk of symptomatic intracranial hemorrhage (multivariable analysis, 5.45 [2.80-10.59], P<0.001; PS-matched analysis, 4.52 [2.24-9.13], P<0.001), but did not increase the in-hospital mortality (multivariable analysis, 0.86 [0.50-1.48], P=0.58; PS-matched analysis, 0.88 [0.52-1.47], P=0.61).
In the setting of clinical practice, intravenous TPA within 4.5 hours improved the functional outcome despite an increased risk of symptomatic intracranial hemorrhage in very elderly Korean patients. The findings, consistent with those from pooled analysis of RCTs, strongly support the use of TPA for this population.
[Show abstract][Hide abstract] ABSTRACT: Background and purpose:
Estimating age- and sex-specific population attributable risks (PARs) of major risk factors for stroke may be a useful strategy to identify risk factors for targeting preventive strategies.
For this case-control matched study, consecutive patients aged 18-90 years and admitted to nine nationwide hospitals with acute ischemic stroke between December 2008 and June 2010, were enrolled as cases. Controls, individually matched by age and sex, were chosen from the 4th Korean National Health & Nutrition Examination Survey (2008-2010). Based on odds ratios and prevalence, standardized according to the age and sex structure of the Korean population, PARs of major risk factors were estimated according to age (young, ≤ 45; middle-aged, 46-65; and elderly, ≥ 66 years) and sex subgroups.
In 4,743 matched case-control sets, smoking (PAR, 45.1%) was the greatest contributing risk factor in young men, followed by hypertension (28.5%). In middle-aged men, the greatest contributing factors were smoking (37.4%), hypertension (22.7%), and diabetes (14.6%), whereas in women the greatest factors were hypertension (22.7%) and stroke history (10.6%). In the elderly, hypertension was the leading factor in men (23.7%) and women (23.4%). Other noticeable factors were stroke history (men, 19.7%; women, 17.3%) and diabetes (men, 12.5%; women, 15.1%). In young women, risk factors with a PAR greater than 10% were not found.
Smoking cessation in young people and hypertension and diabetes control in older people may be effective in reducing the burden of stroke on the population. In the elderly, secondary prevention could also be emphasized.
[Show abstract][Hide abstract] ABSTRACT: Experimental studies suggest that pre-stroke statin treatment has a dual effect of neuroprotection during ischemia and neurorestoration after ischemic injury. The aim of this study was to evaluate the effect of pre-stroke statin use on initial stroke severity and early clinical outcome.
We used a prospective database enrolling patients with acute ischemic stroke from 12 hospitals in Korea between April 2008 and January 2012. Primary endpoint was the initial stroke severity as measured by the National Institutes of Health Stroke Scale (NIHSS) score. Secondary endpoints were good outcome (modified Rankin Scale [mRS], 0-2) and overall mRS distribution at discharge. Multivariable regression model and propensity score (PS) matching were used for statistical analyses.
Among the 8340 patients included in this study, 964 patients (11.6 %) were pre-stroke statin users. The initial NIHSS score (mean [95 % CI]) was lower among pre-stroke statin users vs. non-users in multivariable analysis (5.7 [5.2-6.3] versus 6.4 [5.9-6.9], p = 0.002) and PS analysis (5.2 [4.7-5.7] versus 5.7 [5.4-6.0], p = 0.043). Pre-stroke statin use was associated with increased achievement of mRS 0-2 outcome (multivariable analysis: OR [95 % CI], 1.55 [1.25-1.92], p < 0.001; PS matching: OR [95 % CI], 1.47 [1.16-1.88]; p = 0.002) and favorable shift on the overall mRS distribution (multivariable analysis: OR [95 % CI], 1.29 [1.12-1.51], p = 0.001; PS matching: OR [95 % CI], 1.31 [1.11-1.54]; p = 0.001).
Pre-stroke statin use was independently associated with lesser stroke severity at presentation and better early functional recovery in patients with acute ischemic stroke.
[Show abstract][Hide abstract] ABSTRACT: Higher reperfusion rates have been established with endovascular treatment for acute ischemic stroke patients. There are limited data on the comparative performance of mechanical thrombectomy devices. This study aimed to analyse the efficacy and safety of the stent retriever device (Solitaire stent) by comparing procedure time, angiographic outcome, complication rate and long term clinical outcome with previous chemical thrombolysis and mechanical thrombectomy using penumbra system.
A retrospective single-center analysis was undertaken of all consecutive patients who underwent chemical thrombolysis and mechanical thrombectomy using Penumbra or Solitaire stent retriever from March 2009 to March 2014. Baseline characteristics, rate of successful recanalization (modified Thrombolysis in Cerebral Infarction score 2b-3), symptomatic intracerebral hemorrhage, procedure time, mortality and independent functional outcomes (mRS ≤2) at 3 month were compared across the three method.
Our cohort included 164 patients, mechanical thrombectomy using stent retriever device had a significant impact on recanalization rate and functional independence at 3 months. In unadjusted analysis mechanical thrombectomy using Solitaire stent retriever showed higher recanalization rate than Penumbra system and chemical thrombolysis (75% vs. 64.2% vs. 49.4%, p=0.03) and higher rate of functional independence at 3 month (53.1% vs. 37.7% vs. 35.4%, p=0.213). In view of the interrelationships between all predictors of variables associated with a good clinical outcome, when the chemical thrombolysis was used as a reference, in multiple logistic regression analysis, the use of Solitaire stent retriever showed higher odds of independent functional outcome [odds ratio (OR) 2.62, 95% confidence interval (CI) 0.96-7.17; p=0.061] in comparison with penumbra system (OR 1.57, 95% CI 0.63-3.90; p=0.331).
Our initial data suggest that mechanical thrombectomy using stent retriever is superior to the mechanical thrombectomy using penumbra system and conventional chemical thrombolysis in achieving higher rates of reperfusion and better outcomes. Randomized clinical trials are needed to establish the actual benefit to specific patient populations.
Preview · Article · May 2015 · Journal of Korean Neurosurgical Society
[Show abstract][Hide abstract] ABSTRACT: The alternative fuel jet propellant 8 (JP-8, NATO F-34) can be used as an auto-ignition source instead of diesel. Because it has a higher volatility than diesel, it provides a better air-fuel premixing condition than a conventional diesel engine, which can be attributed to a reduction in particulate matter (PM). In homogeneous charged compression ignition (HCCI) or dual-fuel premixed charge compression ignition (PCCI) combustion or reactivity controlled compression ignition (RCCI), nitrogen oxides (NOx) can also be reduced by supplying external exhaust gas recirculation (EGR). In this research, the diesel and JP-8 injection strategies under conventional condition and dual-fuel PCCI combustion with and without external EGR was conducted. Two tests of dual-fuel (JP-8 and propane) PCCI were conducted at a low engine speed and load (1,500 rpm/IMEP 0.55 MPa). The first test was performed by advancing the main injection timing from BTDC 5 to 35 CA to obtain the emissions characteristics. A fuel ratio of JP-8 to propane of approximately 30:70 was established based on the low heating value of each fuel without the addition of external EGR. The second test investigated the optimal point for low emissions and indicated mean effective pressure (IMEP) with a small amount of external EGR and a post-injection strategy. NOx emissions showed a 'bump' curve with an advancement of the main injection timing. The PM emissions were maintained below 0.63 mg/m3, which reveals almost zero PM emissions. The optimized test results showed appropriate NOx and PM emissions.
[Show abstract][Hide abstract] ABSTRACT: Ontology is one important method by which data is expressed in Semantic Web. For Semantic Web based on ontology, it is important to produce ontology of various domains, but for sharing and expanding ontology, ontology matching work is very important. Using only possessed information of concept in ontology matching has limitation. Therefore, in recent studies, using relationship between concepts, that is, structural information, precision can be being raised. For this, if we use structure-based ontology matching method, its precision can be increased much, but because its complexity metric is quite high, it is difficult to implement this method in large sized ontology. In this study, to decrease complexity metric, a technique with which structural information is changed into sequential information and a DTW algorithm application on ontology matching have been suggested. Also, it has been proved through testing that by implementing the method which has been suggested in this study, the performance of existing multi strategic systems can be improved.
No preview · Article · Feb 2015 · INFORMATION, Japan
[Show abstract][Hide abstract] ABSTRACT: Characteristics of stroke cases, acute stroke care, and outcomes after stroke differ according to geographical and cultural background. To provide epidemiological and clinical data on stroke care in South Korea, we analyzed a prospective multicenter clinical stroke registry, the Clinical Research Center for Stroke-Fifth Division (CRCS-5). Patients were 58% male with a mean age of 67.2±12.9 years and median National Institutes of Health Stroke Scale score of 3 [1-8] points. Over the 6 years of operation, temporal trends were documented including increasing utilization of recanalization treatment with shorter onset-to-arrival delay and decremental length of stay. Acute recanalization treatment was performed in 12.7% of cases with endovascular treatment utilized in 36%, but the proportion of endovascular recanalization varied across centers. Door-to-IV alteplase delay had a median of 45 [33-68] min. The rate of symptomatic hemorrhagic transformation (HT) was 7%, and that of any HT was 27% among recanalization-treated cases. Early neurological deterioration occurred in 15% of cases and were associated with longer length of stay and poorer 3-month outcomes. The proportion of mRS scores of 0-1 was 42% on discharge, 50% at 3 months, and 55% at 1 year after the index stroke. Recurrent stroke up to 1 year occurred in 4.5% of patients; the rate was higher among older individuals and those with neurologically severe deficits. The above findings will be compared with other Asian and US registry data in this article.
[Show abstract][Hide abstract] ABSTRACT: We hypothesized that the relative cerebral blood volume (rCBV) ratio on perfusion-weighted imaging (PWI) using MRI might serve as a predictor of early recanalization (ER) after intravenous tissue plasminogen activator (IV t-PA) administration for acute ischemic stroke.
Patients with acute middle cerebral artery (MCA) ischemic stroke (IS) were enrolled in the study. They were evaluated by MRI, including PWI and diffusion-weighted imaging, before administration of IV t-PA and underwent digital subtraction angiography (DSA) of the brain within 2 h after t-PA administration. We compared the rCBV ratio on PWI between patients with and without ER on DSA and investigated the proportion of patients with an excellent outcome at 90 days after t-PA administration (modified Rankin Scale score 0-1) among those with and without ER.
85 patients with acute MCA IS were included; 16 patients (18.8%) experienced ER on DSA after IV t-PA administration. Patients with ER more frequently had an excellent outcome at 90 days than those without ER. The rCBV ratio on PWI was higher in the ER group (1.01±0.21, p<0.01) than in the non-ER group (0.82±0.18). After adjusting for the presence of atrial fibrillation and the serum glucose level, the rCBV ratio on PWI (OR 1.07; 95% CI 1.02 to 1.12; p<0.01) was a significant independent indicator of ER.
The results of this study suggest that the rCBV ratio on PWI might serve as a useful indicator of ER after IV t-PA administration.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
No preview · Article · Jan 2015 · Journal of Neurointerventional Surgery
[Show abstract][Hide abstract] ABSTRACT: Background A stroke code can shorten time intervals until intravenous tissue plasminogen activator (IV t-PA) treatment in acute ischemic stroke (AIS). Recently, several reports demonstrated that magnetic resonance imaging (MRI)-based thrombolysis had reduced complications and improved outcomes in AIS despite longer processing compared with computed tomography (CT)-based thrombolysis. Methods In January 2009, we implemented CODE RED, a computerized stroke code, at our hospital with the aim of achieving rapid stroke assessment and treatment. We included patients with thrombolysis from January 2007 to December 2008 (prestroke code period) and from January 2009 to May 2013 (poststroke code period). The IV t-PA time intervals and 90-day modified Rankin Scale (mRS) scores were collected. Results During the observation period, 252 patients used IV t-PA under the CODE RED (MRI based: 208; CT based: 44). The remaining 71 patients (MRI based: 53; CT based: 18) received it before the implementation of our stroke code. After implementation of CODE RED, door-to-image time, door-to-needle time, and the onset-to-needle time were significantly reduced by 11, 18, and 22 minutes in MRI-based thrombolysis. Particularly, the proportion of favorable outcome (mRS score 0-2) was significantly increased (from 41.5% to 60.1%, P =.02) in poststroke than in prestroke code period in MRI-based thrombolysis. However, in ordinal regression, the presence of stroke code showed just a trend for favorable outcome (odds ratio,.99-2.87; P =.059) at 90 days of using IV t-PA after correction of age, sex, and National Institutes of Health Stroke Scale. Conclusions In this study, we demonstrated that a systemized stroke code shortened time intervals for using IV t-PA under MRI screening. Also, our results showed a possibility that a systemized stroke code might enhance the efficacy of MRI-based thrombolysis. In the future, we need to carry out a more detailed prospective study about this notion.
No preview · Article · Dec 2014 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
[Show abstract][Hide abstract] ABSTRACT: Voronoi diagrams are powerful for solving spatial problems among particles with different sizes. In particular, the Voronoi diagram of spheres, also called the additively-weighted Voronoi diagram, has proven its powerful capability for solving molecular biology/material science problems in an unified framework. Beta-complex is a generalization of (weighted) alpha-complex and they share similarities and dissimilarities. This paper presents the Beta Concept program which facilitates easy understanding of the powerful capability of the Voronoi diagram, its dual structure, and the beta-complex in the plane. Beta Concept is a Windows program with a graphic user interface written in the standard C++ language and is freely available at the Voronoi Diagram Research Center (http://voronoi.hanyang.ac.kr).
[Show abstract][Hide abstract] ABSTRACT: Background and purpose:
We aimed to generate rigorous graphical and statistical reference data based on volumetric measurements for assessing the relative severity of white matter hyperintensities (WMHs) in patients with stroke.
We prospectively mapped WMHs from 2699 patients with first-ever ischemic stroke (mean age=66.8±13.0 years) enrolled consecutively from 11 nationwide stroke centers, from patient (fluid-attenuated-inversion-recovery) MRIs onto a standard brain template set. Using multivariable analyses, we assessed the impact of major (age/hypertension) and minor risk factors on WMH variability.
We have produced a large reference data library showing the location and quantity of WMHs as topographical frequency-volume maps. This easy-to-use graphical reference data set allows the quantitative estimation of the severity of WMH as a percentile rank score. For all patients (median age=69 years), multivariable analysis showed that age, hypertension, atrial fibrillation, and left ventricular hypertrophy were independently associated with increasing WMH (0-9.4%, median=0.6%, of the measured brain volume). For younger (≤69) hypertensives (n=819), age and left ventricular hypertrophy were positively associated with WMH. For older (≥70) hypertensives (n=944), age and cholesterol had positive relationships with WMH, whereas diabetes mellitus, hyperlipidemia, and atrial fibrillation had negative relationships with WMH. For younger nonhypertensives (n=578), age and diabetes mellitus were positively related to WMH. For older nonhypertensives (n=328), only age was positively associated with WMH.
We have generated a novel graphical WMH grading (Kim statistical WMH scoring) system, correlated to risk factors and adjusted for age/hypertension. Further studies are required to confirm whether the combined data set allows grading of WMH burden in individual patients and a tailored patient-specific interpretation in ischemic stroke-related clinical practice.