Joon Tae Kim

Case Characteristics, Hyperacute Treatment, and Outcome Information from the Clinical Research Center for Stroke-Fifth Division Registry in South Korea

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.

Subarachnoid hemorrhage in a multimodal approach heavily weighted toward mechanical thrombectomy with solitaire stent in acute stroke.

Background and Purpose— Subarachnoid hemorrhage (SAH) may appear on computerized tomography scans after mechanical thrombectomy for acute ischemic stroke. The incidence and prognosis of this observation remain unknown. We investigated the frequency and clinical consequences of SAH after treating acute ischemic stroke with a multimodal approach heavily weighted toward mechanical thrombectomy with Solitaire stent. Methods— Seventy-four consecutive patients with acute ischemic stroke underwent mechanical thrombectomy with a Solitaire stent as a first-line treatment. Nonenhanced computerized tomography scans were performed before, immediately after, and 24 hours after treatment to detect SAH. Clinical outcome was assessed after treatment, on day 1, at discharge, and at 3 months. Clinical and radiological data were compared between patients with and without SAH. Results— Twelve patients (16.2%) exhibited SAH associated with pure SAH (n=4) or mixed SAH and contrast extravasation (n=8). The SAH was located in the ipsilateral Sylvian fissure (n=11) or bilateral parietooccipital sulci (n=1). Patients with SAH had no periprocedural vessel perforations or arterial dissections and no postprocedural neurological deteriorations. Rescue angioplasty was performed more frequently in SAH group than in control group (33.3% vs 9.7%; P=0.05). Patients with SAH and those without had similar recanalization rates and clinical outcomes. Conclusions— SAH on post-therapeutic computerized tomography scans were not uncommon after primary mechanical thrombectomy with a Solitaire stent, but they seemed to be benign. Rescue angioplasty and unidentified, small vessel ruptures due to mechanical stretch during stent retrieval might give rise to these lesions.

Treatment With Tissue Plasminogen Activator in the Golden Hour and the Shape of the 4.5-Hour Time-Benefit Curve in the National United States Get With The Guidelines-Stroke Population

Background: Earlier tissue plasminogen activator treatment improves ischemic stroke outcome, but aspects of the time-benefit relationship still not well delineated are: (1) the degree of additional benefit accrued with treatment in the first 60 minutes after onset, and (2) the shape of the time-benefit curve through 4.5 hours. Methods: We analyzed patients who had acute ischemic stroke treated with intravenous tissue plasminogen activator within 4.5 hours of onset from the Get With The Guidelines-Stroke US national program. Onset-to-treatment time was analyzed as a continuous, potentially nonlinear variable and as a categorical variable comparing patients treated within 60 minutes of onset with later epochs. Results: Among 65u2009384 tissue plasminogen activator–treated patients, the median onset-to-treatment time was 141 minutes (interquartile range, 110–173) and 878 patients (1.3%) were treated within the first 60 minutes. Treatment within 60 minutes, compared with treatment within 61 to 270 minutes, was associated with increased odds of discharge to home (adjusted odds ratio, 1.25; 95% confidence interval, 1.07–1.45), independent ambulation at discharge (adjusted odds ratio, 1.22; 95% confidence interval, 1.03–1.45), and freedom from disability (modified Rankin Scale 0–1) at discharge (adjusted odds ratio, 1.72; 95% confidence interval, 1.21–2.46), without increased hemorrhagic complications or in-hospital mortality. The pace of decline in benefit of tissue plasminogen activator from onset-to-treatment times of 20 through 270 minutes was mildly nonlinear for discharge to home, with more rapid benefit loss in the first 170 minutes than later, and linear for independent ambulation and in-hospital mortality. Conclusions: Thrombolysis started within the first 60 minutes after onset is associated with best outcomes for patients with acute ischemic stroke, and benefit declined more rapidly early after onset for the ability to be discharged home. These findings support intensive efforts to organize stroke systems of care to improve the timeliness of thrombolytic therapy in acute ischemic stroke.

Low-Versus Standard-Dose Alteplase for Ischemic Strokes Within 4.5 Hours A Comparative Effectiveness and Safety Study

Background and Purpose— The low-dose (0.6 mg/kg) alteplase strategy to treat acute ischemic stroke patients became widespread in East Asian countries, without rigorous testing against standard-dose (0.9 mg/kg) alteplase treatment. Our aim was to investigate the comparative effectiveness and safety of the low-dose versus standard-dose intravenous alteplase strategy. Methods— A total of 1526 acute ischemic stroke patients who qualified for intravenous alteplase and treated within 4.5 hours were identified from a prospective, multicenter, and nationwide stroke registry database. Primary outcomes were a modified Rankin scale score of 0 to 1 at 3 months after stroke and occurrence of symptomatic hemorrhagic transformation. Inverse probability of low-dose alteplase weighting by propensity scores was used to remove baseline imbalances between the 2 groups, and variation among centers were also accounted using generalized linear mixed models with a random intercept. Results— Low-dose intravenous alteplase was given to 450 patients (29.5%) and standard-dose intravenous alteplase to 1076 patients (70.5%). Low-dose alteplase treatment was comparable to standard-dose therapy according to the following adjusted outcomes and odds ratios (95% confidence intervals): modified Rankin scale score 0 to 1 at 3 months and 0.95 (0.68–1.32); modified Rankin scale 0 to 2 at 3 months and 0.84 (0.62–1.15); symptomatic hemorrhagic transformation and 1.05 (0.65–1.70); and 3-month mortality and 0.54 (0.35–0.83). The associations were unchanged when the analysis was limited to those without endovascular recanalization. Conclusions— The low-dose alteplase strategy was comparable to the standard-dose treatment in terms of the effectiveness and safety.

Air pollution is associated with ischemic stroke via cardiogenic embolism

Background and Purpose— The aim of the study was to assessed the impact of short-term exposure to air pollution on ischemic stroke subtype, while focusing on stroke caused via cardioembolism. Methods— From a nationwide, multicenter, prospective, stroke registry database, 13u2009535 patients with acute ischemic stroke hospitalized to 12 participating centers were enrolled in this study. Data on the hourly concentrations of particulate matter <10 &mgr;m, nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO) were collected from 181 nationwide air pollution surveillance stations. The average values of these air pollutants over the 7 days before stroke onset from nearest air quality monitoring station in each patient were used to determine association with stroke subtype. The primary outcome was stroke subtype, including large artery atherosclerosis, small-vessel occlusion, cardioembolism, and stroke of other or undetermined cause. Results— Particulate matter <10 &mgr;m and SO2 concentrations were independently associated with an increased risk of cardioembolic stroke, as compared with large artery atherosclerosis and noncardioembolic stroke. In stratified analyses, the proportion of cases of cardioembolic stroke was positively correlated with the particulate matter <10 &mgr;m, NO2, and SO2 quintiles. Moreover, seasonal and geographic factors were related to an increased proportion of cardioembolic stroke, which may be attributed to the high levels of air pollution. Conclusions— Our findings suggest that the short-term exposure to air pollutants is associated with cardioembolic stroke, and greater care should be taken for those susceptible to cerebral embolism during peak pollution periods. Public and environmental health policies to reduce air pollution could help slow down global increasing trends of cardioembolic stroke.

Grading and Interpretation of White Matter Hyperintensities Using Statistical Maps

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. Methods— 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. Results— 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. Conclusions— 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.

Comparative Effectiveness of Standard Care With IV Thrombolysis Versus Without IV Thrombolysis for Mild Ischemic Stroke

Background One third of patients presenting with initially mild strokes have unfavorable outcomes, and the efficacy of intravenous thrombolysis (IVT) in this population has not been proven. This study aimed to evaluate the comparative effectiveness of standard care with IVT versus without IVT in mild stroke patients. Methods and Results Using a multicenter stroke registry database, we identified patients with acute ischemic stroke who presented within 4.5 hours of symptom onset and had initial National Institutes of Health Stroke Scale scores ≤5. Multivariable logistic analysis and propensity score matching were used to adjust for baseline imbalances between the patients who did and did not receive IVT. Adjusted odds ratios and 95% CIs of IVT were estimated for 3‐month modified Rankin Scale scores of 0 to 1 and symptomatic. Of 13 117 patients with stroke who were hospitalized between April 2008 and May 2012, 1386 met the eligibility criteria, and 194 (14.0%) were treated with IVT. For a modified Rankin Scale of 0 to 1 at 3 months, the adjusted odds ratios were 1.96 (95% CI, 1.28 to 3.00; P=0.002) by multivariable logistic analysis and 1.68 (1.10 to 2.56; P=0.02) by propensity score matching analysis, respectively. There was a statistically nonsignificant excess of symptomatic hemorrhagic transformation (odds ratios=3.76 [0.95 to 16.42; P=0.06] and 4.81 [0.84 to 49.34; P=0.09]), respectively. Conclusions In this observational registry‐based study, standard care with IVT is more effective than not receiving IVT in mild ischemic stroke patients, and there is a statistically nonsignificant risk of symptomatic hemorrhagic transformation.

Effect of pre-stroke statin use on stroke severity and early functional recovery: a retrospective cohort study

BackgroundExperimental 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.MethodsWe 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.ResultsAmong the 8340 patients included in this study, 964 patients (11.6xa0%) were pre-stroke statin users. The initial NIHSS score (mean [95xa0% 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], pu2009=u20090.002) and PS analysis (5.2 [4.7–5.7] versus 5.7 [5.4–6.0], pu2009=u20090.043). Pre-stroke statin use was associated with increased achievement of mRS 0–2 outcome (multivariable analysis: OR [95xa0% CI], 1.55 [1.25–1.92], pu2009<u20090.001; PS matching: OR [95xa0% CI], 1.47 [1.16-1.88]; pu2009=u20090.002) and favorable shift on the overall mRS distribution (multivariable analysis: OR [95xa0% CI], 1.29 [1.12-1.51], pu2009=u20090.001; PS matching: OR [95xa0% CI], 1.31 [1.11-1.54]; pu2009=u20090.001).ConclusionsPre-stroke statin use was independently associated with lesser stroke severity at presentation and better early functional recovery in patients with acute ischemic stroke.

Stroke outcomes are worse with larger leukoaraiosis volumes

Leukoaraiosis or white matter hyperintensities are frequently observed on magnetic resonance imaging of stroke patients. We investigated how white matter hyperintensity volumes affect stroke outcomes, generally and by subtype. In total, 5035 acute ischaemic stroke patients were enrolled. Strokes were classified as large artery atherosclerosis, small vessel occlusion, or cardioembolism. White matter hyperintensity volumes were stratified into quintiles. Mean age (± standard deviation) was 66.3 ± 12.8, 59.6% male. Median (interquartile range) modified Rankin Scale score was 2 (1–3) at discharge and 1 (0–3) at 3 months; 16.5% experienced early neurological deterioration, and 3.3% recurrent stroke. The Cochran-Mantel-Haenszel test with adjustment for age, stroke severity, sex, and thrombolysis status showed that the distributions of 3-month modified Rankin Scale scores differed across white matter hyperintensity quintiles (P < 0.001). Multiple ordinal logistic regression analysis showed that higher white matter hyperintensity quintiles were independently associated with worse 3-month modified Rankin Scale scores; adjusted odds ratios (95% confidence interval) for the second to fifth quintiles versus the first quintile were 1.29 (1.10–1.52), 1.40 (1.18–1.66), 1.69 (1.42–2.02) and 2.03 (1.69–2.43), respectively. For large artery atherosclerosis (39.0%), outcomes varied by white matter hyperintensity volume (P = 0.01, Cochran-Mantel-Haenszel test), and the upper three white matter hyperintensity quintiles (versus the first quintile) had worse 3-month modified Rankin Scale scores; adjusted odds ratios were 1.45 (1.10–1.90), 1.86 (1.41–2.47), and 1.89 (1.41–2.54), respectively. Patients with large artery atherosclerosis were vulnerable to early neurological deterioration (19.4%), and the top two white matter hyperintensity quintiles were more vulnerable still: 23.5% and 22.3%. Moreover, higher white matter hyperintensities were associated with poor modified Rankin Scale improvement: adjusted odds ratios for the upper two quintiles versus the first quintile were 0.66 (0.47–0.94) and 0.62 (0.43–0.89), respectively. For small vessel occlusion (17.8%), outcomes tended to vary by white matter hyperintensitiy volume (P = 0.10, Cochran-Mantel-Haenszel test), and the highest quintile was associated with worse 3-month modified Rankin Scale scores: adjusted odds ratio for the fifth quintile versus first quintile, 1.98 (1.23–3.18). In this subtype, worse white matter hyperintensities were associated with worse National Institute of Health Stroke Scale scores at presentation. For cardioembolism (20.6%), outcomes did not vary significantly by white matter hyperintensity volume (P = 0.19, Cochran-Mantel-Haenszel test); however, the adjusted odds ratio for the highest versus lowest quintiles was 1.62 (1.09–2.40). Regardless of stroke subtype, white matter hyperintensities were not associated with stroke recurrence within 3 months of follow-up. In conclusion, white matter hyperintensity volume independently correlates with stroke outcomes in acute ischaemic stroke. There are some suggestions that stroke outcomes may be affected by leukoaraiosis differentially depending on stroke subtypes, to be confirmed in future investigations.

Comparative Effectiveness of Prestroke Aspirin on Stroke Severity and Outcome

The effect of prestroke aspirin use on initial severity, hemorrhagic transformation, and functional outcome of ischemic stroke is uncertain.