Management of carotid artery stenosis.

The incidence of both ischemic and hemorrhagic stroke is more common in Asians compared to Caucasian (1). It is found there is a decreased incidence of ischemic stroke in Northern America but increased incidence in Africa, Mongolia and southeast Asia. In the epidemiological study of carotid artery stenosis (CAS), Framingham study showed the prevalence of significant extracranial CAS was 7% in women and 9% in men (2). Among all strokes in Caucasian population, 20 to 30% were due to extracranial CAS and 5 to 10% due to intracranial atherosclerosis (3, 4). Northern Manhattan stroke study also found intracranial atherosclerosis could be seen in 6 to 10% of ischemic strokes in white patients, but up to 29% among African Americans and Hispanics (5). Intracranial artery stenosis was more frequently found in Chinese population than extracranial artery stenosis with the range of 3.7% - 70.4% of intracranial CAS and 1.5%-49% of extracranial CAS (6). Intracranial artery stenosis is more common in Asian, Hispanic, and African-American populations. In hospitalized patients with symptomatic intracranial stenosis, it was only 1% in non-Hispanic whites, while 50% in Asian populations. Population-based studies revealed the prevalence of symptomatic intracranial disease was 1 in 100,000 for whites to 15 in 100,000 for African Americans, but 7% of the population aged more than 40 years for Chinese (7). Concurrent atherosclerosis of extracranial and intracranial arteries was also common in Asians. It was reported 10% to 48% in patients with symptomatic cerebrovascular disease, and 21% of stroke patients had concurrent stenoses in Hong Kong, 33% in China, 18% in Taiwan, and 48% of patients with more than 30% extracranial carotid stenosis had concurrent intracranial stenosis in South Korea (8). The study of concomitant atherosclerotic arterial diseases showed in patients with more than 50% significant CAS, the most frequent artery was coronary artery disease which was found in 68% of patients, while renal artery stenosis and limb artery stenosis were found in 20% and 21% of patients, respectively (9). Carotid artery stenosis of 70% or greater was detected in 37.7% patients with cerebrovascular disease, 24.5% patients with peripheral arterial disease, and 11.1% patients with coronary artery disease (10). Significant extracranial carotid and vertebral artery disease (ECCVD) identified by duplex ultrasonography is not uncommon in Chinese patients with coronary artery disease (CAD), and 22.9% ECCVD was seen in patients with CAD, comparable with that reported in white populations (11). In our Stroke Registry In Chang-Gung Healthcare System (SRICHS) from 2008 to 2011 (Fig. 1), we found large artery atherosclerosis (LAA) occupied 19.5% of total ischemic stroke patients and 3.1% had concurrent atrial fibrillation (12).