Evolution of Ischemic Stroke Subtypes in Hong Kong

Stroke is the 4th leading cause of mortality in Hong Kong. It also carries considerable socioeconomical consequences due to disability. Ischemic stroke can be classified by the TOAST classification, which includes large artery atherosclerosis, cardioembolism, small-artery occlusion and other causes (1). Among which, intracranial atherosclerosis (ICAS) had been major cause of acute ischemic stroke (AIS) in the Asia Pacific. It was estimated as high as 24.1% of AIS or transient ischemic attacks (TIAs) were attributed to ICAS in China (2). Management of ICAS related strokes has been challenging owing to its high rate of recurrence despite medical therapy. Recent randomized clinical trial suggested that aggressive medical therapy may result in reduction in recurrence compared with historical cohorts (3). Our group has previously observed a 2.5-fold increase in atrial fibrillation related stroke over a 15-year period (4). The inverstigator also observed a decline in ICAS related AIS as well as its recurrent stroke risk throughout the recent years. Possible mechanisms include better management of metabolic risk factors and aggressive secondary prevention. Other possible reasons are increased atrial fibrillation (AF), small vessel disease (SVD) or other stroke mechanisms. This study is aim to find the evolution of different stroke subtypes in relation to the characteristics of our stroke population over a 15-year period. This may influence territorial prevention strategy.