Low-attenuation plaques (LAPs) are associated with an increased risk of cardiovascular mortality and morbidity. South Asians experience poorer cardiovascular outcomes compared to Caucasian populations. We hypothesised that South Asian population has a higher prevalence of LAP compared to Caucasians and this difference predicts major adverse cardiovascular events. 72 Caucasian and 72 Morise score-matched South Asian patients were identified from a cardiac computed tomography angiography (CCTA) registry. Coronary artery plaque subtypes in proximal major epicardial and left main arteries were analysed from CCTA images using pre-determined attenuation ranges in Hounsfield units (HUs): 1 to 30 HU (low attenuation), 31 to 70 HU (intermediate attenuation), 71 to 150 HU (high attenuation), and mean coronary lumen + 2 standard deviations to 1000 HU (calcified). For each analysis, data comparison was performed for plaque volumes after normalising for the corresponding coronary artery outer vessel wall volume. The baseline characteristics and total plaque score of the two cohorts were similar. There were no statistically significant differences in low, intermediate, and high- attenuation, or calcified normalised plaque volumes between Caucasian and Morise score-matched South Asian cohorts. After a mean follow up of 32 months, major adverse cardiovascular events were similar between Caucasians and South Asians. In a Morise score-matched ethnicity study, we found no significant differences in plaque subtypes including LAP in South Asians compared to a Caucasian cohort. Other factors accounting for poor outcomes in South Asians should be investigated.
Keywords: Caucasian; Coronary plaque characteristics; Low-attenuation plaques; Morise score; South Asian.