Increased Cerebral Artery Atherosclerosis in Korea more common in Caucasians.2,3,14 However, most of the recent data from Asian patients has been based upon findings from a small number of patients or from transcra- nial Doppler studies, which may result in a selection bias of patients included or arteries assessed.3,14-16 It is not possi- ble to perform conventional angiography, which is invasive, in all stroke patients. Therefore, in addition to a potential bias in patient selection, it might have been difficult to discern the pattern of EC or IC atherosclerosis in stroke patients as a whole. There was virtually no selection bias in using the angiographic studies in our study cohort by using MRA as well as DSA. Therefore, we could estimate global frequency as well as distribution of atherosclerosis. As a result, we showed that combined EC and IC atheros- clerosis is most common in Korean stroke patients. Among individual arteries, the MCA was the most commonly involved site, consistent with previous findings in Asian populations.13,16 Though in a DSA-only subgroup the involvement of the extracranial ICA was most com- mon, this result could have been biased as patients who were found to have severe stenosis of the extracranial ICA on MRA would have undergone additional DSA before carotid endarterectomy or stenting. In a recent German study, the extracranial ICA was the most common symp- tomatic site of atherosclerosis, followed by the MCA.20 These findings suggest that the ICA in the extracranial portion and the MCA in the intracranial portion are the most vulnerable sites for atherosclerosis regardless of race, though a difference in frequency exists. While the exact etiology of this pattern of racial difference remains uncer- tain, environmental as well as genetic factors have been suggested as contributing causes.21 The difference in risk factors among races has been also suggested as a cause, as the frequency of hypertension, diabetes, and obesity is greater in black, Chinese, Japanese, and Hispanic indivi- duals compared to Caucasians.22 Because approximately 92% of the consecutive patients enrolled for this study period had angiographic studies, we could investigate a temporally changing pattern of atheros- clerosis. Of note, the frequency and burden of atheroscle- rosis have been rapidly increasing in our study cohort, which were coupled to an increase in vascular risk factors. Korea is a representative country in Asia that is rapidly developing and has been significantly affected by wester- nized lifestyles during the last decade. It has been suggested that westernized lifestyles aggravate risk factors for atherosclerosis and contribute to the progression of precli- nical atherosclerosis.23 Accumulating evidence indicates that there have been rapid changes in the prevalence of vascular risk factors among the Korean population, most of which are related to lifestyle changes.7,24,25 The prevalence of hypertension in Korea has increased from 19.6% in 1990 to 27.0% in 2001.8 Moreover, in the 2001 survey, only 10.7% of hypertensive patients had their blood pressures adequately controlled. Thus, a recent and rapid increase in several vascular risk factors may in part be responsible for the increasing atherosclerotic burden. In the present study, a significant increase in the presence of risk factors was also noted. Among these risk factors, hyperten- sion and diabetes mellitus have increased, consistent with observations in the Korean general population.8,26 With the exception of smoking, classic risk factors for stroke were associated with EC or IC atherosclerosis with multiple logistic regression analysis. In addition, the num- ber of risk factors was associated with the burden of atheros- clerosis, suggesting a cumulative impact of risk factors on EC and IC atherosclerosis. Previous studies in stroke-free patients showed that the prevalence of IC atherosclerosis escalated with an increasing number of vascular risk factors27 and that combined EC and IC atherosclerosis was associated with a greater number of risk factors, consistent with our findings. The incidence of ischemic and total cerebrovascular events was greater in the combined EC and IC group when compared to the isolated EC and IC groups.28 These findings suggest that atherosclerosis in cerebral arteries could be substantially decreased by reducing the prevalence of vascular risk factors. Given their cumulative impacts, it is essential to identify and reduce the well-known determinants of these risk factors. Although the findings of this study were based upon a Korean population, many Asian countries may also undergo rapid lifestyle changes. Studies in Asian populations, including Japanese and Chinese, have shown that migration from traditional to westernized environments is associated with modification in diet and lifestyle, often leading to undesirable changes in blood sugar, lipid profile, and BMI and an increase in the risk of cardiovascular events.12,23,29,30 Likewise, the incidence of hypertension has been increas- ing in Asian counties, and the proportion of adequately controlled hypertensives remains low.31 Actually, in a study comparing the angiographic findings of Japanese stroke patients between 1963-65 and 1989-93, the proportion of patients with EC atherosclerosis was found to be higher in recent years.32 It is therefore likely that other Asian coun- tries share the issues raised in this study, which further increases the burden of cerebral artery atherosclerosis. Our study has several potential limitations. This is a single hospital-based study in patients with a symptomatic ischemic stroke, and the results were obtained from a certain part of Korea. Therefore, application of our data to the general population and to other countries should be cautious. While DSA is the gold standard for evaluating cerebral arteries, MRA as well as DSA was used in this study. MRA could erroneously detect false atherosclerotic Yonsei Med J http://www.eymj.org Volume 51 Number 3 May 2010 323