Original Paper Eur Neurol 2013;69:179–184 DOI: 10.1159/000342892
Received: May 10, 2012 Accepted: August 6, 2012 Published online: December 29, 2012
Differences of Ankle-Brachial Index according to Ischemic Stroke Subtypes: The Peripheral Artery Disease in Korean Patients with Ischemic Stroke (PIPE) Study Pil-Wook Chung a Dae-Hyun Kim b Hahn Young Kim c Kwang-Yeol Park d Tai Hwan Park e Ji Man Hong f Gyeong-Moon Kim g Oh Young Bang g Kyungmi Oh h Soo Joo Lee i a
Department of Neurology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Department of Neurology, Dong-A University College of Medicine, Busan, c Department of Neurology, Konkuk University School of Medicine, d Department of Neurology, Chung-Ang University Medical Center, Chung-Ang University College of Medicine, and e Department of Neurology, Seoul Medical Center, Seoul, f Department of Neurology, Ajou University School of Medicine, Suwon, g Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, and h Department of Neurology, Korea University Medical Center, Seoul, and i Department of Neurology, Eulji University Hospital, Eulji University School of Medicine, Daejeon, Republic of Korea b
Key Words Ankle-brachial index Ischemic stroke Stroke subtype
Abstract Background/Aims: Although previous studies showed a high prevalence of abnormal ankle-brachial index (ABI) in patients with ischemic stroke, few data exist regarding ABI in Asian patients with ischemic stroke. The purpose of the present study was to determine the prevalence and factors associated with abnormal ABI (^0.9) in a cohort of ischemic stroke patients. Methods: In this prospective multicenter study, 1,293 patients diagnosed with acute ischemic stroke or transient ischemic attack underwent ABI measurement to evaluate an association between abnormal ABI and vascular risk factors and clinical characteristics. Differences in ABI by stroke subtypes were also assessed. Results: Abnormal ABI of ^0.9 was found in 13.0%. Patients with abnormal ABI were more likely to be older and had higher initial stroke severity.
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The prevalence of abnormal ABI was 18.4% in large artery atherosclerosis, 7% in small artery disease, and 19.2% in cardioembolism (p ! 0.001). Multiple logistic regression analysis showed that age, hyperlipidemia, diabetes, and large artery atherosclerosis subtype were independent factors associated with abnormal ABI. Conclusions: These data suggest that the prevalence of abnormal ABI in Korean patients with ischemic stroke was lower than that in Caucasian patients, which might be associated with ethnic differences in underlying stroke subtypes. Copyright © 2012 S. Karger AG, Basel
Introduction
The ankle-brachial index (ABI) is an easy and reliable tool to identify patients with subclinical peripheral arterial disease (PAD) [1]. Low ABI has been established as a risk marker for cardiovascular disease and mortality Soo Joo Lee, MD, PhD Department of Neurology, Eulji University Hospital Eulji University School of Medicine, 1306, Dunsan-Dong Seo-Gu, Daejeon 302-799 (Republic of Korea) E-Mail sjoolee @ eulji.ac.kr
both in the general population as well as in patients with established coronary artery disease [2–6]. Recent reports have suggested a high prevalence of low ABI among patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA), with prevalence estimates ranging from 31 to 51% [4, 7, 8]. Additionally, low ABI is also associated with an increased all-cause mortality and an increased risk of cardiovascular events in patients with ischemic stroke [4, 8]. Vascular disease in one arterial territory strongly predicts disease in other vascular territories [9]. Despite reports of an increased prevalence of abnormal ABI in ischemic stroke patients, limited prevalence data exists regarding abnormal ABI among Asian patients with AIS. As such, the present study aims to assess the prevalence of low ABI among ethnic Korean patients hospitalized for AIS or TIA, as well as evaluate the factors associated with low ABI in this population.
Methods The Peripheral Artery Disease in Korean Patients with Ischemic Stroke (PIPE) Study is an observational, prospective, multicenter study that aims to evaluate the prevalence of abnormal ABI among patients with AIS or TIA and the associated 1-year outcomes with an ABI value in this population. The present study is the initial cross-sectional analysis of this prospective trial. Subjects This study was conducted in the department of neurology of nine tertiary referral hospitals. Between January 2010 and December 2010, consecutive patients with AIS or TIA within 7 days of symptom onset were enrolled in each of the participating hospitals. Diagnosis of stroke was confirmed by CT and/or MRI scan of the brain. All patients were evaluated per stroke registry protocol, which includes demographic characteristics, vascular risk factor assessment, ABI measurement, and medical history (specifically focusing on prior stroke, history of peripheral artery disease, and coronary artery disease). Stroke subtypes were classified according to the TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria [10]. Exclusion criteria for ABI assessment included severe disabling stroke precluding ABI measurement, discharge prior to ABI measurement, and refusal to participate in this study. 194 patients refused to participate in the study, 64 did not undergo the ABI test due to severe and unstable neurological state, 30 were discharged or transferred prior to investigation, and 2 patients were excluded due to other undefined reasons. Therefore, 290 of 1,583 screened patients were excluded from this study. All patients provided written informed consent for study participation. The study protocol was approved by the ethics committees of all participating hospitals prior to recruitment.
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Risk Factors All patients were included in a computerized database and their demographic characteristics, vascular risk factors and therapies during hospitalization were recorded. The following risk factors were assessed in the present study. Patients were diagnosed as having hypertension if they were receiving antihypertensive medication or had a blood pressure 1140/90 mm Hg on repeated measurement at least 1 week after stroke onset. Patients were diagnosed as having diabetes mellitus if they were currently being treated with insulin or oral hypoglycemic agents or if their fasting blood glucose level was 6126 mg/ dl on two separate occasions. Smoking status was defined as current smoking. Hypercholesterolemia was defined as taking a cholesterol-lowering agent or fasting cholesterol level 6220 mg/dl. Coronary artery disease was defined as a history of myocardial infarction, coronary angioplasty, coronary artery bypass surgery, or angina pectoris. Atrial fibrillation was diagnosed on the basis of prior history of atrial fibrillation or at least one electrocardiogram during hospitalization. Ankle-Brachial Index Measurement The ABI test was performed by specially trained nurses after the patient rested in the supine position for 5 min. Ankle and brachial systolic blood pressures were measured with a sphygmomanometer and a hand-held 8-MHz Doppler probe (Smartdrop 30EX; Hadeco, Kawasaki, Japan). ABI was calculated according to the AHA recommendations [11]. ABI was calculated as the ratio of the higher of the systolic pressure of the posterior tibial or dorsalis pedis artery to the higher of right and left brachial artery pressures. ABI was calculated separately for each leg, and the lower of the two ABI values were included in the analysis. ABI values ^0.9 were defined as low and were considered to represent subclinical PAD; an ABI of 0.91–1.4 was defined normal. An ABI of 11.4 was defined as noncompressible and was excluded from this analysis given the relative rarity of these values (n = 4) in this study. Statistical Analysis Statistical analyses were performed to identify the differences between patients with normal ABI and those with abnormal ABI. Clinical characteristics, vascular risk factors, and stroke subtypes were compared between the two groups. Either the Student t test or Mann-Whitney U test were used to analyze continuous variables, while the 2 test was used for categorical variables. Multivariable analyses were performed via multiple logistic regression to determine the factors associated with abnormal ABI. Variables with p values !0.1 in univariate analysis were included in the multivariable analysis. All statistical analyses were performed using PASW statistics 17.0 (SPSS, Inc., Chicago, Ill., USA).
Results
Of the 1,583 patients with AIS or TIA, 1,293 (81.7%) underwent ABI measurement and were included in this study. The included patients consisted of 758 (58.6%) men, were all Korean, and the mean age was 65.5 8 12.4 Chung /Kim /Kim /Park /Park /Hong / Kim /Bang /Oh /Lee
Table 1. Comparison of clinical characteristics between ABI groups
Abnormal ABI (n = 168) Male gender Age, years Vascular risk factors Hypertension Diabetes Hyperlipidemia Coronary heart disease Previous stroke Current smoking Atrial fibrillation Laboratory profiles Systolic blood pressure, mm Hg Fasting glucose, mg/dl Total cholesterol, mg/dl Triglyceride, mg/dl LDL, mg/dl White blood cells Clinical profiles Initial NIHSS Index event Cerebral infarction TIA Previous PAD symptoms TOAST classification LAA SAD (lacunar infarct) CE Undetermined Other etiology
Normal ABI (n = 1,125)
p
103 (61.3) 70.9810.4
655 (58.2) 64.7812.5
0.461
