Jinkwon Kim

Brain glucose metabolic changes associated with neuropsychological improvements after 4 months of treatment in patients with obsessive-compulsive disorder.

Objective:  The study was designed to elucidate regional brain metabolic changes according to a treatment and their relationship with neuropsychological performance changes in obsessive–compulsive disorder (OCD).

Robust algorithm for arrhythmia classification in ECG using extreme learning machine.

BackgroundRecently, extensive studies have been carried out on arrhythmia classification algorithms using artificial intelligence pattern recognition methods such as neural network. To improve practicality, many studies have focused on learning speed and the accuracy of neural networks. However, algorithms based on neural networks still have some problems concerning practical application, such as slow learning speeds and unstable performance caused by local minima.MethodsIn this paper we propose a novel arrhythmia classification algorithm which has a fast learning speed and high accuracy, and uses Morphology Filtering, Principal Component Analysis and Extreme Learning Machine (ELM). The proposed algorithm can classify six beat types: normal beat, left bundle branch block, right bundle branch block, premature ventricular contraction, atrial premature beat, and paced beat.ResultsThe experimental results of the entire MIT-BIH arrhythmia database demonstrate that the performances of the proposed algorithm are 98.00% in terms of average sensitivity, 97.95% in terms of average specificity, and 98.72% in terms of average accuracy. These accuracy levels are higher than or comparable with those of existing methods. We make a comparative study of algorithm using an ELM, back propagation neural network (BPNN), radial basis function network (RBFN), or support vector machine (SVM). Concerning the aspect of learning time, the proposed algorithm using ELM is about 290, 70, and 3 times faster than an algorithm using a BPNN, RBFN, and SVM, respectively.ConclusionThe proposed algorithm shows effective accuracy performance with a short learning time. In addition we ascertained the robustness of the proposed algorithm by evaluating the entire MIT-BIH arrhythmia database.

Red blood cell distribution width is associated with poor clinical outcome in acute cerebral infarction

Increased red blood cell distribution width (RDW), which is a marker of anisocytosis, is associated with mortality and cardiovascular events in the general population and in patients with heart failure or coronary heart disease. We investigated whether RDW in acute cerebral infarction is predictive of functional outcome and mortality. A total of 847 consecutive patients with first-ever acute cerebral infarction who presented to the emergency department within seven days of symptom onset were enrolled in this study. We investigated the association of RDW with poor functional outcome (modified Rankin Scale >2) and all-cause mortality at three months, as well as survival time for one year after stroke onset. Multivariate logistic regression revealed that higher RDW was independently associated with poor functional outcome (adjusted odds ratio [OR], 1.222 per 1% increment in RDW, 95% confidence interval [CI] 1.059-1.409, p=0.006) and all-cause death (adjusted OR, 1.395 per 1% increment in RDW, 95% CI 1.168-1.665, p<0.001) at three months after stroke onset. RDW was an independent predictor of survival in multivariate Cox-proportional regression model (adjusted hazard ratio, 1.328 per 1% increment in RDW, 95%CI 1.178-1.498, p<0.001). The addition of RDW to a survival model significantly increased predictability for survival across the entire follow-up period (weighted average of the area-under the curves, 0.858 vs. 0.841, p<0.05). In conclusion, higher RDW measured in cases of acute stage cerebral infarction was associated with poor functional outcome and mortality. RDW may be used as a biomarker for the prediction of long-term outcomes in patients with acute cerebral infarction.

Different prognostic value of white blood cell subtypes in patients with acute cerebral infarction

OBJECTIVE We aimed to investigate the relationship of each white blood cells (WBC) subtype with neurologic severity and outcome in acute stroke. METHODS We included 779 patients with first-ever acute cerebral infarction within 72 h after symptom onset. We investigated the association between counts for WBC subtypes in peripheral blood at admission and (1) initial stroke severity; (2) early change in stroke severity within one week; and (3) functional outcome at three months. RESULTS Higher total WBC and neutrophil counts were associated with more severe stroke at admission (p<0.001). In contrast, lower lymphocyte counts were associated with a lesser improvement during the first week after admission (p<0.05) and with poor functional outcome at three months (OR=0.706 per 1000 lymphocyte counts/mm(3), p=0.020). CONCLUSIONS Our study merits further investigation on the role of each WBC subtype in ischemic injury and different prognostic value of WBC subtypes measured at admission in acute stroke.

Increases in Cerebral Atherosclerosis According to CHADS2 Scores in Patients With Stroke With Nonvalvular Atrial Fibrillation

Background and Purpose— The CHADS2 score is used for risk stratification of ischemic stroke in patients with nonvalvular atrial fibrillation and high CHADS2 scores are associated with increased risk of stroke. Most components of the CHADS2 score are also risk factors for atherosclerosis. Therefore, high CHADS2 scores can be associated with concomitant cerebral atherosclerosis and subsequently atherothrombotic stroke. The aim of this study was to determine whether there are differences in the presence and burden of concomitant cerebral atherosclerosis according to CHADS2 scores in patients with stroke with nonvalvular atrial fibrillation. Methods— We included 780 consecutive patients with nonvalvular atrial fibrillation who had undergone angiographic studies at index stroke between August 1994 and March 2010 in the present study. We investigated the relationships between the CHADS2 score and the presence, severity, and pattern of cerebral atherosclerosis and stroke mechanism. Results— Of the 780 patients, concomitant arterial stenosis (≥50%) was found in 231 patients (29.6%). The number of arteries with atherosclerosis increased as the CHADS2 score increased (P<0.001) as did the proportion of combined extracranial and intracranial atherosclerosis (P<0.001). Multivariate analyses showed that high risk based on the CHADS2 score was an independent predictor of concomitant cerebral atherosclerosis (OR, 3.121; 95% CI, 1.770 to 5.504) and the presence of proximal stenosis at the symptomatic artery (OR, 3.043; 95% CI, 1.458 to 6.350). Conclusions— The CHADS2 score can predict the presence of concomitant cerebral artery atherosclerosis. Increased risk of stroke in patients with high CHADS2 scores may be partly explained by increased frequency and burden of cerebral atherosclerosis.

Long-Term Mortality in Patients With Stroke of Undetermined Etiology

Background and Purpose— The determination of stroke etiology is essential for planning treatment for stroke prevention. However, the etiology of stroke is undetermined in many patients. Methods— During a 10-year period, consecutive patients with acute ischemic stroke were enrolled. The stroke etiology was determined based on the Trial of ORG 10172 in Acute Stroke Treatment classification. Long-term mortality and causes of death were identified using death certificates. The standardized mortality ratio was calculated to compare the mortality in patients with stroke and that in the general Korean population. Results— In total, 3278 patients were enrolled and followed-up for a median of 3.4 years (interquartile range, 1.5–5.7). The stroke subtype was undetermined in 37% because of negative evaluation (21.2%), multiple causes (10.6%), and incomplete evaluation (4.8%). Poor functional outcome at 3 months (modified Rankin scale score >2) was more frequent in patients with an incomplete evaluation than in those with the other stroke subtypes (49.6% vs 24.5%; P<0.001). During follow-up, 781 patients (23.8%) died. The overall cumulative death rate was highest in patients with an incomplete evaluation (12.7% within 30 days, 25.5% within 1 year, and 35.7% within 3 years), followed by those with cardioembolism. Multivariate analysis after adjusting for covariates including initial stroke severity, the mortality of patients with an incomplete evaluation was second lowest after cardioembolism, whereas that in patients with a negative evaluation was low. Conclusions— Long-term mortality in patients with an incomplete evaluation was quite high. Etiologic work-up helps to better define the stroke subtype and determine the prognosis.

Association of cerebral microbleeds with mortality in stroke patients having atrial fibrillation

Objectives: We investigated the association of cerebral microbleeds (CMBs) with long-term mortality in patients with nonvalvular atrial fibrillation (NVAF) according to burden and distribution of CMBs. Methods: This was a retrospective, hospital-based, observational study. In total, 504 consecutive ischemic stroke patients with NVAF who underwent brain T2-weighted, gradient-recalled echo MRI were included. Data for the date and causes of death were based on the death certificates from the Korean National Statistical Office. We determined the association of the presence, burden, and distribution of CMBs with mortality from all-cause, ischemic heart disease, ischemic stroke, and hemorrhagic stroke. Results: CMBs were found in 30.7% of patients (155/504). During a median follow-up of 2.5 years, 176 patients (34.9%) died (ischemic stroke, 81; hemorrhagic stroke, 12; ischemic heart disease, 32). Patients with CMBs died more frequently than those without (41.9% vs 31.8%, p = 0.028). After adjusting for age, sex, and other significant variables, the presence of multiple (≥5) CMBs was as an independent predictor for all-cause (hazard ratio [HR]: 1.99) and ischemic stroke (HR: 3.39) mortality. Patients with strictly lobar CMBs had an increased risk of hemorrhagic stroke mortality (HR: 5.91). Conclusions: The presence and burden of CMBs were associated with increased mortality in stroke patients with NVAF. Patients with lobar CMBs were at increased risk of death due to hemorrhagic stroke. The diagnosis of CMBs is of value in predicting long-term prognosis in stroke patients with NVAF.

The association between cerebral atherosclerosis and arterial stiffness in acute ischemic stroke.

OBJECTIVE Arterial stiffness is associated with cardiovascular risk factors and atherosclerosis. Measurement of pulse wave velocity (PWV) is one of the most representative and noninvasive techniques for assessing arterial stiffness. We investigated the association of cerebral atherosclerosis with brachial-ankle PWV (baPWV) in acute ischemic stroke patients. If present, we sought to determine whether the relationship differed between atherosclerosis in the intracranial artery and atherosclerosis in the extracranial artery. METHODS We included 801 patients with acute ischemic stroke who had undergone angiographic study and baPWV measurement between January 2007 and May 2010. Patients with cerebral artery atherosclerosis were categorized into those with intracranial atherosclerosis, those with extracranial atherosclerosis and those with both intracranial and extracranial atherosclerosis. We determined factors that were associated with baPWV. RESULTS Univariate and multivariate analyses showed that high baPWV was significantly associated with older age, lower body mass index, higher brachial systolic pressure, and diabetes mellitus. Increased baPWV was associated with the presence of atherosclerosis (≥ 50% stenosis) in the intracranial cerebral artery as well as in both the intracranial and extracranial arteries, but not with atherosclerosis in the extracranial cerebral artery. The burden of intracranial cerebral atherosclerosis, which was assessed based on the number of arteries with atherosclerosis, was also closely associated with baPWV. CONCLUSION Arterial stiffness was associated with the presence and burden of intracranial cerebral atherosclerosis in stroke patients, but was not associated with the extracranial cerebral atherosclerosis. These findings suggest a potential pathophysiological association between increased arterial stiffness and intracranial cerebral atherosclerosis.

The frequency and risk of preclinical coronary artery disease detected using multichannel cardiac computed tomography in patients with ischemic stroke.

Background: Atherosclerosis is a systemic disease. Many ischemic stroke patients may have concomitant coronary artery disease (CAD). Detection and treatment of preclinical CAD in stroke patients may improve long-term outcome and survival because CAD is a major cause of death during follow-up in stroke patients. However, association between coronary and cerebral artery atherosclerosis in stroke patients has not fully been investigated. This study aimed at examining the frequency and high-risk groups of CAD in ischemic stroke patients. Methods: Consecutive patients who were admitted due to acute ischemic stroke between July 2006 and June 2010 were prospectively enrolled in this study. A total of 1,304 patients who underwent MSCT coronary angiography and cerebral angiography were included in this study. By using 64-multislice computed tomography coronary angiography, we investigated the frequency of CAD and association between coronary and cerebral artery atherosclerosis in terms of location and burden (severity and extent) in stroke patients. We also sought to identify high-risk groups for CAD among stroke patients. Results: The frequency of significant (≧50%) CAD was 32.3% and the frequency of any degree of CAD was 70.1%. Diabetes mellitus, serum levels of total cholesterol, high-density lipoprotein cholesterol and triglyceride, and significant stenosis of the extracranial carotid, intracranial vertebral and basilar arteries were independently associated with CAD. However, no association was found between CAD and significant stenosis of the anterior, middle and posterior cerebral arteries. The association between CAD and cerebral atherosclerosis was stronger with increased severity and extent of cerebral atherosclerosis. When compared to patients with <2 risk factors and without significant cerebral atherosclerosis, those with multiple (≧2) risk factors and atherosclerosis in both the carotid and the vertebrobasilar arteries had very high risks of CAD [odds ratio (OR) 8.36; 95% confidence interval (CI) 4.15–16.87]. The risk was also high in patients with multiple risk factors and atherosclerosis in either the carotid or the vertebrobasilar artery (OR 4.13; 95% CI 2.62–6.51), and in those with <2 risk factors but atherosclerosis in both the carotid and the vertebrobasilar arteries (OR 3.40; 95% CI 1.22–9.47). Conclusions: A substantial portion of stroke patients had preclinical CAD, and there was a clear relationship between coronary and cerebral artery atherosclerosis in terms of location and burden. The risk of CAD was particularly high in stroke patients with multiple risk factors and atherosclerosis of the carotid and/or vertebrobasilar arteries.

Interarm blood pressure difference and mortality in patients with acute ischemic stroke

Objective: The objective of this study was to assess the prognostic value of interarm difference of blood pressure (IAD) measured in acute ischemic stroke and to investigate its association with systemic atherosclerosis. Methods: This was a hospital-based retrospective observational study. Survival data and systolic/diastolic IAD were collected in patients with acute ischemic stroke. Systemic atherosclerosis was determined based on coronary CT angiography, transesophageal echocardiography, ankle-brachial index examination, and cerebral angiography covering both intracranial and extracranial cerebral arteries. Results: Of 834 patients, 10.3% had a systolic IAD ≥10 mm Hg, and 6.0% had a diastolic IAD ≥10 mm Hg. During a mean follow-up period of 2.96 ± 0.95 years, 92 patients died (including 68 cardiovascular deaths). In multivariate Cox regression adjusted for cardiovascular risk factors and initial stroke severity, the presence of systolic IAD ≥10 mm Hg was associated with increased risk of all-cause mortality (hazard ratio [HR] 1.97, 95% confidence interval [CI] 1.16–3.35) and cardiovascular mortality (HR 2.49, 95% CI 1.39–4.46). Patients with diastolic IAD ≥10 mm Hg also had increased risk of all-cause mortality (HR 3.43, 95% CI 1.94–6.08) and cardiovascular mortality (HR 3.51, 95% CI 1.83–6.74). The presence of systolic or diastolic IAD ≥10 mm Hg was associated with peripheral artery disease in the lower limbs, but not with atherosclerosis in the cerebral artery, coronary artery, or the aorta. Conclusions: The presence of interarm systolic or diastolic blood pressure difference ≥10 mm Hg is a strong independent prognostic marker in acute ischemic stroke.