Aims: Positive coronary arterial remodelling has been shown to be associated with unstable coronary syndromes and ex vivo histological characteristics of plaque vulnerability such as a large lipid core and high macrophage content. The aim of this study is to evaluate the in vivo association between coronary artery remodelling and underlying plaque characteristics identified by optical coherence tomography (OCT). OCT is a unique imaging modality capable of characterizing these important morphological features of vulnerable plaque.
Methods and results: OCT and intravascular ultrasound imaging was performed at corresponding sites in patients undergoing catheterization. OCT plaque characteristics for lipid content, fibrous cap thickness, and macrophage density were derived using previously validated criteria. Thin-cap fibroatheroma (TCFA) was defined as lipid-rich plaque (two or more quadrants) with fibrous cap thickness <65 microm. Remodelling index (RI) was calculated as the ratio of the lesion to the reference external elastic membrane area. A total of 54 lesions from 48 patients were imaged. Positive remodelling compared with absent or negative remodelling was more commonly associated with lipid-rich plaque (100 vs. 60 vs. 47.4%, P = 0.01), a thin fibrous cap (median 40.2 vs. 51.6 vs. 87 microm, P = 0.003) and the presence of TCFA (80 vs. 38.5 vs. 5.6%, P < 0.001). Fibrous cap macrophage density was also higher in plaques with positive remodelling showing a positive linear correlation with the RI (r = 0.60, P < 0.001).
Conclusion: Coronary plaques with positive remodelling exhibit characteristic features of vulnerable plaque. This may explain the link between positive remodelling and unstable clinical presentations.