Abstract 895: Distance From the Coronary Ostium as a Predictor of Vulnerable Plaque Morphology; An In-vivo Optical Coherence Tomography Study
Background: Plaque morphology predicts its vulnerability to cause acute coronary events; most of which occur due to disruption of lipid-rich thin-cap fibroatheroma (TCFA). Observational studies show that lesions causing acute events are clustered in the proximal coronary artery segments.
Aim: To evaluate whether the location of plaque in the coronary vessel is predictive of vulnerable plaque morphology identified by optical coherence tomography (OCT).
Methods: OCT was performed in patients undergoing catheterization. Plaque distance (PD) from the ostium was measured with angiography using standardised projections. A cut point derived from the median PD was used to define proximal and distal coronary segments. Lipid was quantified on OCT images as the number of quadrants on the cross-sectional image. TCFA were defined as lipid rich plaque with a fibrous cap thickness <65 μm. Macrophage content was calculated as the normalized standard deviation of the optical signal within the fibrous cap.
Results: 61 plaques from 50 patients were analysed. Mean age was 58 years. Median PD was 39mm (10.4–89.1). Proximal location was associated with plaque with a higher lipid content (Figure⇓). Plaques classified as TCFA were more frequent in proximal compared to distal segments (57% vs 20%, p = 0.018). There was a trend toward a higher macrophage density in proximal plaques (6.3 vs 5.3, p = 0.1). In a logistic regression model, with patient demographics and presentation as covariates, proximal location was an independent predictor of TCFA (p = 0.027).
Conclusion: Proximal location of plaque within the coronary artery is independently predictive of vulnerable plaque morphology.