| Object: As the diagnostic indicator of peripheral arterial disease (PAD),ankle-brachial index (ABI) has predictive value for the risk ofcardiovascular ischemic events[1]. Foreign studies[2-4]have confirmed that lowABI increased the risk of ischemic stroke, especially the large-arteryatherosclerosis (LAA)[3]. LAA can be further divided into simple intracranialcarotid stenosis (ICAS) and simple extracranial carotid stenosis (ECAS),besides, for the differences exist in vessels structure and hemodynamic,various vascular risk factors contribute to ECAS and ICAS differently.So it isnecessary to study the relationship between abnormal ABI and ECAS or ICASand then to assess whether a low ABI provides predictive value for the futurecardiovascular risk independently of other risk markers in patients after stroke.Hence, we recruited stroke patients,used ABI<0.95as an indicator[5]to reflectthe relationship between low ABI and ECAS or ICAS. Furthermore, studywhether a low ABI could independently predict the long-term cardiovascularrisk and the mortality in patients with ECAS and ICAS.Methods: This study included available consecutive patients due toischemic stroke and admitted into Department of Neurology, Third Hospital ofHebei Medical University from Dec.2011to Dec.2012.We screened thepatients who were clearly diagnosed as LAA and small artery disease (SAD)as research subjects. In the period of admission, all patients had standardetiology diagnose through history of disease, clinical manifestations, clinicalimaging and laboratory tests. A sphygmomanometer and doppler device withan8-MHz continuous-wave probe was used for the measurement of ABI.The diagnostic criteria of ECAS and ICAS was according to the results ofmagnetic resonance imaging (MRA), carotid duplexultrasonography,computed tomography (CT) and transcranial doppler sonography (TCD). The specific diagnostic criteria was according to theliteratures[6-8].Measurements of all patients’ ABI were conducted by an experiencedsonographer. The measurement and calculation methods of ABI referred to thereferences[9-10]. According to the domestic and foreign results[5,10], we use ABI<0.95and ABI≥1.3as abnormal ABI: ABI <0.95represented low ABI; ABI≥1.3represented high ABI;0.95≤ABI <1.3represented normal ABI.Based on the different parts of atherosclerosis, patients were divided intofour parts: symptomatic ICAS group, symptomatic ECAS group, combinedICAS and ECAS group and SAD group. All enrolled patients had ABI bemeasured. We recorded the patient’s age, gender and all cardiovascular riskfactors including: hypertension, diabetes, hyperlipidemia, smoking, history ofischemic stroke, family history of stroke, coronary atherosclerotic heartdisease and PAD. Multivariate logistic regression was used to analyze therelationship between low ABI and symptomatic ECAS and symptomaticICAS.We set the enrolled time as the starting following point and collected theinformation via telephone, outpatient follow-up and re-admission records. Thefollowing time was a2-years period, when the endpoint events appearedincluding myocardial infarction, coronary stenting, heart bypass surgery,stroke, all-cause and vascular death, the follow-up was end. Recorded theincidence of endpoint events and survival time (in months). Multivariate coxsurvival analysis was used to assess:(1) the predictive value of low ABI forendpoint events risk of all enrolled patients;(2) the predictive value of lowABI for stroke recurrence risk in ECAS group and ICAS group.Count data were shown as positive cases or constitute ratio. Rates betweenthe two groups were compared using χ2test. Logistic regression analysis wasused to analyze the correlation between abnormal ABI and ECAS or ICAS;Cox proportional hazard model was used to analyze survival analysis, P＜0.05was considered statistically significant. SPSS19.0software was used forstatistical analysis. Results:1Demographic situation and the incidence of low ABIWe recruited an inception cohort of300consecutive patients with acuteischemic stroke. The mean age of all patients was64.45±10.412. Thenumber of male was185(61.67%) and female was115(38.33%). The ECASgroup was composited by121(40.33%) patients and the number of ICASgroup was53(17.67%), SAD was81(27.00%).35.3%of patients had a lowABI,49.05%of ECAS had a low ABI, compared with29.75%of ICAS group,the difference was statistically significant (χ2=4.00，P=0.045).2Correlation analysis of low ABI and symptomatic ECAS, ICASIn multivariable logistic analyses，major risk factors for ECAS includedlow ABI (HR=2.284，95％CI1.027-5.083，P=0.043),smoking(HR=2.368，95％CI1.122-4.995， P=0.024) and diabetes (HR=3.726，95％CI1.740-7.978， P=0.001). Only hypertension (HR=2.251，95％CI1.181-4.290，P=0.014) was the independent risk factors for ICAS.3Predictive value of Low ABI for cardiovascular eventsAccording to the multivariable cox regression analysis:23.3%patientsexperienced outcome events, the rate was higher among patients with a lowABI compared with those with a normal ABI (32%vs15.24%), the differencewas statistically significant,(χ2=7.112，P=0.008).In univariate Cox regression analysis, after adjustment for age, gender,diabetes and other risks of cardiovascular, patients with a low ABI had a2.24times higher risk of endpoint events (HR=2.24，95％CI1.189-4.218，P=0.013) and high ABI was2.38times higher. Other factors associated with thecomposite outcome in univariate analysis were diabetes (HR=1.999，95％CI1.111-3.597，P=0.021).After adjustment for age, gender, diabetes and other risks ofcardiovascular, abnormal ABI does not appear to predict long-term strokerecurrence of all patients, ECAS group and ICAS group by univariate Coxregression analysis.Conclusion: ABI＜0.95was the independent risk factors for ICAS. ABI ＜0.95in patients with ischemic stroke is associated with increased2-yearcardiovascular event risk and mortality. However, low ABI does not appear topredict long-term stroke recurrence of all ischemic stroke or ECAS and ICAS. |
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