Jisung Lee

The Significance of Blood Pressure Variability for the Development of Hemorrhagic Transformation in Acute Ischemic Stroke

Background and Purpose— Elevated blood pressure (BP) is commonly observed in acute ischemic stroke and is known to be associated with hemorrhagic transformation (HT). However, the effect of BP variability on the development of HT is not known well. Methods— A consecutive series of patients with acute ischemic stroke, who were hospitalized within 24 hours of onset and showed no HT on initial gradient echo MRI, were enrolled in this study. BP measurements during the first 72 hours were obtained, and BP variability of each patient was described using various summary parameters: SD, maximum (max), minimum (min), difference between max and min (max−min), average squared difference between successive measurements (sv), and maximum sv (svmax). Results— Of 792 patients meeting the eligibility criteria, 70 (8.8%) developed HT. Among BP variability parameters categorized into quartiles, SBPmax, SBPmin, SBPmax−min, SBPsvmax, DBPSD, DBPmax, DBPmin, DBPmax−min, and DBPsvmax were significantly associated with HT independent of mean SBP, age, interval from onset to arrival, initial stroke severity, diabetes mellitus, stroke subtype, thrombolysis, initial glucose, and total cholesterol (P<0.05 on likelihood ratio test of trend). The analyses about the interaction between thrombolysis and variability parameters showed that the effects of BP variability on the development of HT did not differ by whether patients received thrombolysis or not. Conclusions— Our study suggests that we may consider not only the absolute level of BP but also its variability to prevent hemorrhagic transformation.

Risk Factors Associated With the Presence of Unruptured Intracranial Aneurysms

Background and Purpose— With the increased investigation of cerebral arteries using magnetic resonance angiography in the general population, the detection of unruptured intracranial aneurysms (UIAs) has increased. Understanding the distribution and factors associated with UIAs might be helpful for understanding the pathomechanism. Methods— Subjects who underwent magnetic resonance angiography with a health examination at the Health Screening and Promotion Center were enrolled. The incidence and risk factors of UIAs (age, sex, hypertension, diabetes mellitus, smoking, alcohol, and coronary artery disease) were investigated by comparing patients with and without UIAs. These risk factors were also investigated by the UIA location, distal internal carotid artery, anterior cerebral artery and middle cerebral artery (MCA), MCA bifurcation, anterior and posterior communicating artery, and posterior circulation. Results— Among 187 166 subjects who received health examination, 18 954 underwent magnetic resonance angiography. Of them, 367 (1.93%) had UIAs. Age (odds ratio [OR], 1.02; P=0.003), women (OR, 2.00; P<0.001), hypertension (OR, 2.21; P<0.001), smoking (OR, 1.66; P=0.001), and coronary artery disease (OR, 0.23; P<0.001) were independently associated with the presence of UIAs. Hypertension was associated with most UIAs, except for those located at sidewalls (anterior cerebral artery and MCA). MCA aneurysms were associated with old age and smoking. Distal internal carotid artery, posterior communicating artery, and MCA-bifurcation aneurysms were associated with female sex. Anterior communicating artery aneurysms were associated with smoking and alcohol. Posterior circulation UIAs were only associated with hypertension. Coronary artery disease was negatively associated with anterior circulation aneurysms. Conclusions— The risk factors for UIAs differ by their location, compared with the control. Interestingly, the presence of coronary artery disease was protective against the presence of UIAs.

Associations of cigarette smoking with intracranial atherosclerosis in the patients with acute ischemic stroke

BACKGROUNDnAlthough cigarette smoking has been established as an important risk factor for stroke, the effect on the atherosclerotic stenosis, which are based on observational studies, have been controversial. We set out to examine the differences in the risk factors between smokers and nonsmokers and to investigate the association of cigarette smoking with cerebral arterial stenosis.nnnMETHODSnA total of 989 consecutive patients with acute noncardioembolic ischemic stroke were prospectively enrolled from June 2004 to January 2010. The risk factor profiles were compared between smokers and nonsmokers. We analyzed the degree of stenosis in all MRA, and evaluated influencing factors in the patients with intracranial atherosclerosis (ICAS) and extracranial atherosclerosis (ECAS) who were randomly matched by age and sex.nnnRESULTSnThere were differences in the distribution of risk factors between the 467 (70.0%) nonsmokers and the 215 (30.0%) smokers. Nonsmokers were older (71.7±11.0 versus 61.7±12.0, p<0.001) and had a higher frequency of hypertension than smokers had (75.4% versus 64.0%, p=0.002). When smokers and nonsmokers were age- and sex-matched, smoking was more prevalent in patients with ICAS than with ECAS (32.9% versus 28.2%). Conditional regression analysis revealed that smoking and hypertension increased the odds of ICAS [smoking, odds ratio (OR): 1.83, p=0.026; hypertension, OR: 1.84, p=0.01], whereas hyperlipidemia increased the odds of ECAS (OR: 1.87, p=0.034).nnnCONCLUSIONnThe distributions of the major risk factors for ischemic stroke were different between smokers and nonsmokers. Cigarette smoking may be more associated with ICAS than with ECAS after adjusting for potential risk factors.

Impact of post-stroke cognitive impairment with no dementia on health-related quality of life.

Background and Purpose Health-related quality of life (HRQoL) is a multidimensional concept that signifies a subjective evaluation of perceived health; hence, it has gained wide acceptance in geriatrics. However, its application has not been tested in patients with post-stroke cognitive impairment with no dementia (PSCIND). We investigated whether PSCIND interferes with HRQoL measured by EQ-5D, compared the findings to those of healthy people with normal cognition, and evaluated the influence of each cognitive domain on this score. Methods In total, 1,528 subjects were identified who had undergone neuropsychological assessment using the 60-min protocol of the Korean version of Vascular Cognitive Impairment Harmonization Standards, EQ-5D, and magnetic resonance imaging at the stroke prevention clinic. Fifty PSCIND patients were matched to 50 post-stroke dementia (PSD) patients and 50 normal age- (±3 years) and sex-matched controls. The effects of PSCIND, PSD, and control groups upon the EQ-5Dindex score were tested by generalized estimating equation modeling. Results Estimated means±standard errors of EQ-5Dindex scores were as follows: 0.94±0.06 (control group), 0.86±0.08 (PSCIND group), and 0.61±0.32 (PSD group); and the difference among the three groups was statistically significant (P<0.0001). Pairwise comparisons showed that EQ-5Dindex scores in the PSCIND group differed from those in the PSD and control groups (both P<0.01). No cognitive domain was specifically associated with EQ-5Dindex scores after adjusting for functional status. Conclusions This study shows that PSCIND may interfere with the quality of life in stroke victims.

Differential Effect of Previous Antiplatelet Use on Stroke Severity According to Stroke Mechanism

Background and Purpose— The effect of previous antiplatelet use on stroke severity is controversial. We assume that this controversy is attributable to its difference according to the stroke mechanism. Methods— Using a prospective stroke registry, patients who were hospitalized because of ischemic stroke and had relevant lesions on MRI were selected. Patients who were using anticoagulants or whose stroke subtype was categorized as stroke of other determined etiology or undetermined etiology were excluded. Baseline stroke severity was measured using the National Institutes of Health Stroke Scale scores at presentation and was compared between no previous antiplatelet users and previous antiplatelet users with stratification by stroke subtypes. Results— Among the 1622 patients, a total of 490 (30.2%) patients reported use of an antiplatelet within 1 week of stroke onset. The baseline National Institutes of Health Stroke Scale score showed no difference between the nonantiplatelet and antiplatelet groups by crude comparison. However, the interaction between previous antiplatelet use and stroke subtype was significant (P=0.023) in a multivariable analysis; when the study subjects were stratified by stroke subtype, the difference in baseline National Institutes of Health Stroke Scale between the nonantiplatelet and platelet groups was significant in the large artery atherothrombosis group but not in those with cardioembolism and small-vessel occlusion before and after adjustments. Conclusions— Our study suggests that the reduction of initial stroke severity in the previous antiplatelet users may differ by stroke mechanism.

Weekend Admission in Patients with Acute Ischemic Stroke Is Not Associated with Poor Functional Outcome than Weekday Admission

Background and Purpose Stroke requires consistent care, but there is concern over the weekend effect, whereby a weekend admission results in a poor outcome. Our aim was to determine the impact of weekend admission on clinical outcomes in patients with acute ischemic stroke in Korea. Methods The outcomes of patients admitted on weekdays and weekends were compared by analyzing data from a prospective outcome registry enrolling 1247 consecutive patients with acute ischemic stroke admitted to four neurology training hospitals in South Korea between September 2004 and August 2005. The primary outcome was a poor functional outcome at 3 months, defined as modified Rankin Scale (mRS) of 3-6. Secondary outcomes were 3-month mortality, use of thrombolysis, complication rate, and length of hospitalization. Shift analysis was also performed to compare overall mRS distributions. Results On weekends, 334 (26.8%) patients were admitted. Baseline characteristics were comparable between the weekday and weekend groups except for more history of heart disease and shorter admission time in weekend group. Univariate analysis revealed poor functional outcome at 3 months, 3-month mortality, complication rate, and length of hospitalization did not differ between the two groups. In addition, overall mRS distributions were comparable (p=0.865). After adjusting for baseline factors and stroke severity, weekend admission was not associated with poor functional outcome at 3 months (adjusted odds ratio, 1.05; 95% CI, 0.74-1.50). Furthermore, none of secondary endpoints differed between the two groups in multivariate analysis. Conclusions Weekend admission was not associated with poor functional outcome than weekday admission in patients with acute ischemic stroke in this study. The putative weekend effect should be explored further by considering a wider range of hospital settings and hemorrhagic stroke.

Cardiac Vulnerability to Cerebrogenic Stress as a Possible Cause of Troponin Elevation in Stroke

Background Troponin elevation with electrocardiography changes is not uncommon in patients with acute ischemic stroke; however, it is still unclear whether the mechanism of these changes is due to cardiac problems or neurally mediated myocytic damage. Thus, we investigated cardiac and neurological predictors of troponin elevation in those patients. Methods and Results We retrospectively analyzed medical data of the prospectively registered ischemic stroke patients on stroke registry who were admitted and underwent a serum cardiac troponin I and 12‐lead electrocardiography within 24 hours of symptom onset. However, patients with well‐known troponin‐elevating comorbidities were excluded from the analysis. Among 1404 ischemic stroke patients, 121 (8.7%) had elevated troponin, which was defined as more than 0.04 mg/mL. Multivariable analysis identified electrocardiography abnormalities such as QTc‐prolongation (odds ratio [OR]: 1.52, 95% CI: 1.02–2.28), left ventricular hypertrophy (OR: 2.14, 95% CI 1.43–3.19), Q‐wave (OR: 2.53, 95% CI: 1.48–4.32), and ST elevation (OR: 2.74, 95% CI: 1.12–6.72) as cardiac variables associated with troponin elevation, and higher National Institutes of Health Stroke Scale score (OR: 1.04, 95% CI: 1.01–1.07) and insular cortical lesions (OR: 2.78, 95% CI: 1.85–4.19) as neurological variables associated with troponin elevation. Incidence of troponin elevation as well as QTc‐prolongation was increased further in combination with cardiac and neurological factors. Conclusions Certain cardiac and neurological conditions in acute ischemic stroke may contribute to troponin elevation. The proposed concept of cardiac vulnerability to cerebrogenic stress can be a practical interpretation of troponin elevation and electrocardiography abnormalities in stroke patients.

Medial Temporal Atrophy and Memory Dysfunction in Poststroke Cognitive Impairment-No Dementia

Background and Purpose It was recently reported that the prevalence of poststroke memory dysfunction might be higher than previously thought. Stroke may exist concomitantly with underlying Alzheimers disease (AD), and so we determined whether post-stroke memory dysfunction indicates manifestation of underlying subclinical AD. Methods Of 1201 patients in a prospective cognitive assessment database, we enrolled subjects with poststroke amnestic vascular cognitive impairment-no dementia (aVCIND; n=48), poststroke nonamnestic vascular cognitive impairment-no dementia (naVCIND; n=50), and nonstroke amnestic mild cognitive impairment (aMCI; n=65). All subjects had cognitive deficits, but did not meet the criteria for dementia. A standardized neuropsychological test battery and magnetic resonance imaging were performed at least 90 days after the index stroke (mean, 473 days). Visual assessment of medial temporal atrophy (MTA) was used as a measure of underlying AD pathology. Results The MTA score was significantly lower in the naVCIND group (0.64±0.85, mean±SD) than in the aVCIND (1.10±1.08) and aMCI (1.45±1.13; p<0.01) groups. Multivariable ordinal logistic regression analysis revealed that compared with naVCIND, aVCIND [odds ratio (OR)=2.69; 95% confidence interval (CI)=1.21-5.99] and aMCI (OR=5.20; 95% CI=2.41-11.23) were significantly associated with increasing severity of MTA. Conclusions Our findings show that compared with poststroke naVCIND, the odds of having more-severe MTA were increased for poststroke aVCIND and nonstroke aMCI.

Association between Hypertriglyceridemia and Lacunar Infarction in Type 2 Diabetes Mellitus

BACKGROUNDnAlthough recent studies have shown that the elevation of serum triglyceride (TG) is related to the increased incidence of ischemic stroke, the relationship between hypertriglyceridemia and subtypes of ischemic stroke is largely unknown. This study attempted to evaluate whether hypertriglyceridemia is associated with lacunar stroke in diabetes mellitus (DM).nnnMETHODSnA total of 2141 consecutive patients with acute ischemic stroke were enrolled from March 2005 to April 2014, excluding the subjects with undetermined/other determined etiology or no lipid data. We compared the lipid profiles among stroke subtypes. The estimated serum TG levels and the interaction between DM and stroke subtypes were determined by analysis of covariance (ANCOVA) and Tukeys multiple comparison.nnnRESULTSnIn ANCOVA test, the difference of estimated TG between DM and non-DM patients was largest in small-vessel occlusion (SVO; 159.7 [95% confidence interval {CI}, 143.2-176.2] versus 122.4 [95% CI, 106.1-138.7]), and a significant interaction was observed between DM and stroke subtypes for TG levels (P = .013) but not for total cholesterol (P = .363), low-density lipoprotein cholesterol (P = .171), or high-density lipoprotein cholesterol (P = .231). By Tukeys multiple comparison, SVO was consistently associated with DM for serum TG levels (P < .001).nnnCONCLUSIONSnIn acute ischemic stroke with DM, serum TG level was significantly associated with lacunar infarction adjusting for other lipid profiles and vascular risk factors. Further studies are warranted to reveal the pathophysiologic implication of hypertriglyceridemia for lacunar infarction in type 2 DM.

A simple oscillator design with the frequency controlled by patch size

A simple design for antenna-integrated planar oscillator with convenient controlling of operating frequency is presented. The oscillator circuit consists of a broadband negative-resistance active part and a passive load including a patch antenna. In the proposed design, patch antenna is resonator as well as radiating element. Hence, the antenna radiation frequency automatically becomes oscillation frequency. To verify the design method, two negative resistance circuits capable of supporting oscillation over full C-band and X-band are fabricated. The oscillation frequencies, output powers and phase noises at 100-KHz offset for different patch antennas are measured.