Young Dae Kim, et al. lesions, particularly in intracranial arteries. However, an increasing trend of atherosclerosis was also observed in a subgroup using DSA, indicating that the findings and con- clusions in our study were not impacted by the use of MRA data. While patients with PCSE were supposed to be excluded from the analysis, some patients who had PCSE that are particularly dependent on echocardiographic studies might be included because TEE was not performed in many patients. However, it is impossible to perform TEE in all patients since it requires that a patient is coo- perating, and most PCSE, which are detected on echocar- diographic studies in patients with sinus rhythm, are medium or low risk sources such as patent foramen ovale or spontaneous echo contrast.33 Furthermore, findings of increasing frequency and burden of atherosclerosis during the recent eight year period were not changed whether or not patients with PCSE were excluded for the analysis in this study. Finally, although the metabolic syndrome may be one of the important risk factors for atherosclerosis that can be affected by lifestyle changes, it was not included in the present analysis because the presence of the metabolic syndrome was not added to our registry until 2003. Despite these potential limitations, the present large- scaled study of Korean stroke patients who were enrolled consecutively for the recent eight-year period demonstrated that combined EC and IC atherosclerosis is the most common form and that its presence and burden have been increasing. The increase of atherosclerotic burden was coupled to an increase in risk factors for atherosclerosis, which is presumed to be, in part, related to lifestyle changes. Urgent concerns and efforts to prevent or reduce atheros- clerotic burden are necessary in Korea, and possibly in other Asian countries that may also undergo westernized lifestyle changes. ACKNOWLEDGEMENTS This work was supported by a grant of the Korea Healthcare Technology R & D Project, Ministry for Health, Welfare & Family Affairs, Republic of Korea (A060171, A085136) and supported by KOSEF through the National Core Research Center for Nanomedical Technology (R15-2004- 024-00000-0). REFERENCES 1. Gorelick PB, Caplan LR, Hier DB, Patel D, Langenberg P, Pessin MS, et al. Racial differences in the distribution of posterior circulation occlusive disease. Stroke 1985;16:785-90. 2. Caplan LR, Gorelick PB, Hier DB. Race, sex and occlusive cerebrovascular disease: a review. Stroke 1986;17:648-55. 3. Wong KS, Huang YN, Gao S, Lam WW, Chan YL, Kay R. Intracranial stenosis in Chinese patients with acute stroke. Neurology 1998;50:812-3. 4. Dahlöf B. Prevention of stroke in patients with hypertension. Am J Cardiol 2007;100:17J-24. 5. Enbergs A, Bürger R, Reinecke H, Borggrefe M, Breithardt G, Kerber S. 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Arch Neurol 2006;63:1287-91. 324 Yonsei Med J http://www.eymj.org Volume 51 Number 3 May 2010