Comparing ultrasonographically assessed carotid and abdominal aorta plaques in cardiovascular disease risk estimation

Individual risk estimation is an essential part of cardiovascular (CV) disease prevention. Several imaging parameters have been studied for this purpose. Based on mounting evidence, international guidelines recommend the ultrasound assessment of carotid artery plaques to refine individual risk estimation. Previous studies have not compared carotid artery and abdominal aorta plaques in CV risk estimation. Our aim was to explore this matter in a prospective study setting.

Participants were part of the Oulu Project Elucidating Risk of Atherosclerosis (OPERA) project. All participants (n = 1007, 50% males, aged 51.3 ± 6.0 years) were clinically examined in the beginning of 1990's and followed until the end 2014 for fatal and non-fatal CV events.

During a median follow-up of 22.5 (17.5-23.2) years, 246 (24%) participants suffered a CV event and 79 (32%) of those CV events were fatal. When compared to those without plaques, both carotid (hazard ratio, HR 2.854 [95% confidence interval, CI, 2.188-3.721, p < 0.001) and abdominal aorta plaques (HR 2.534 [1.503-4.274], p < 0.001) were major risk factors for CV events as an aggregate endpoint. These associations remained even after adjusting the multivariable models with age, sex, systolic blood pressure, smoking, diabetes, LDL cholesterol, and with previous CV events (coronary artery disease and stroke/transient ischemic attack). However, only carotid plaques were significant risk factors for fatal CV events: multivariable adjusted HR 2.563 (1.452-4.524), p = 0.001. Furthermore, reclassification and discrimination parameters were improved only when carotid plaques were added to a baseline risk model. Adding abdominal aorta plaques to the baseline risk model improved C-statistic from 0.718 (0.684-0.751) to 0.721 (0.688-0.754) whereas carotid plaques improved it to 0.743 (0.710-0.776).

Both carotid and abdominal aorta plaques are significant risk factors for CV events, but only carotid plaques provide prognostic information beyond traditional CV risk factors on fatal CV events. If one ultrasound parameter for plaque detection and CV risk estimation had to be chosen, carotid plaques may be preferred over abdominal aorta.