(P271) CAROTID PLAQUE BORDER ULCERATION IS ASSOCIATED WITH CORONARY ARTERY DISEASE AND FUTURE CARDIOVASCULAR EVENTS

Background: The majority of cardiovascular events are caused by atherosclerosis and subsequent plaque rupture. Recently, increasing evidence has suggested that plaque vulnerability to rupture, rather than plaque quantity, increases cardiovascular risk. Plaque surface ulceration has been associated with intraplaque hemorrhage and rupture, thus is a useful marker for assessing plaque instability. Fractal analysis is an emerging tool that assesses the complexity of a region of interest using a box-counting algorithm. This technique has been validated as a tool to quantify carotid plaque border irregularity. The objective of this study was to use fractal analysis to assess the relationship between ultrasound-detected carotid plaque surface irregularity, coronary artery disease (CAD), and cardiovascular risk.

METHODS AND RESULTS: Carotid B-mode ultrasound was performed on 458 consecutive participants referred for coronary angiography. Fractal analysis was performed on the carotid plaques in the long-axis view of B-mode ultrasound images. The region of interest was manually selected and the plaque border was extracted by computing edges in the areas of the highest gradient magnitude using Fiji software (Figure 1). Fractal dimension (FD) was computed for all plaques in the carotid bifurcation and the proximal 1 cm of the internal and external carotid arteries. The FDs of all plaque lesions were averaged to obtain an overall FD value per patient. The mean FD in the sample population was 1.1628±0.043. FD was significantly higher in participants with significant CAD (≥50% stenosis) than in those without significant CAD (1.1679±0.045 vs. 1.1545±0.039, p=0.003). Multivariate logistic regression demonstrated that FD was a significant independent risk factor for significant CAD. Additionally, Kaplan Meier analysis showed that an FD>1.1500 was associated with a significantly higher occurrence of 30-day cardiovascular events (p=0.045) (Figure 2). Multivariate Cox proportional hazards analysis demonstrated that FD was a significant and independent contributor to 30-day cardiovascular events (odds ratio: 1.85; 95% confidence interval: 1.02-3.54; p=0.04).

Conclusion: Fractal dimension is increased in patients with significant CAD and increased FD is associated with 30-day cardiovascular events. The relationship between the fractal dimension of carotid plaque lesions and cardiovascular outcomes established in the present study could facilitate its use as an imaging biomarker for cardiovascular risk.