Obstructive sleep apnea is associated with increased coronary plaque instability: an optical frequency domain imaging study

Figures

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  Fig. 1. Representative plaque images from optical frequency domain imaging (OFDI). a Ruptured plaque (white arrow) with fibrous cap discontinuity leading to communication between the lipid core (LC) and lumen. b Measurement of the lipid arc for a lipid-rich plaque. The maximum lipid arc was measured within a lipid-rich plaque (yellow lines). c A cholesterol crystal was defined as a thin, linear region of high signal intensity within the lipid plaque, without backscattering. d Measurement of fibrous cap thickness. The thickness was measured at the thinnest point three times, and the average was taken (white arrows). e Macrophage accumulation was defined as increased signal intensity within the fibrous cap, accompanied by heterogeneous backward shadows (arrowheads). f Microchannels were defined as small vesicular or tubular structures with diameters of 50–300 μm within the intima

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  Fig. 2. Semiquantification of macrophage accumulation in optical frequency domain imaging (OFDI). Representative cross–sectional OFDI images with the following grades: a grade 0, no macrophages; b grade 1, localized accumulation; c grade 2, clustered accumulation in < 1 quadrant; d grade 3, clustered accumulation in ≥ 1 and < 3 quadrants; and e grade 4, clustered accumulation in ≥ 3 quadrants

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  Fig. 3. Relationships of apnea hypopnea index (AHI) with plaque characteristics. AHI was significantly correlated with a lipid index (r = 0.400, P < 0.001) b minimum fibrous cap thickness (r = − 0.315, P = 0.008) c macrophage grade (r = 0.453, P < 0.001), and d number of microchannels (r = 0.431, P < 0.001), but not with e maximum thickness of calcification (r = 0.094, P = 0.440)