Imaging of Triglycerides in Human Coronary Plaques by Color Fluorescent Angioscopy and Microscopy

Native triglycerides (TG) deposited in the human vascular wall is not measurable or visible in vivo to date. We discovered that by exciting fluorescence at 345 nm and emitting at 420 nm, 3-amino-4-hydroxy-5-nitrobenzene sulfonic acid monohydrate (3-ANA) elicits a brown fluorescence that is characteristic of just TG. Therefore, localization of TG in coronary plaques and normal segments that were obtained from 19 human autopsy cases was examined by color fluorescent angioscopy (CFA) and microscopy using 3-ANA as a biomarker of TG. By CFA, the percentage (%) incidence of TG in 23 normal segments, 13 white plaques without lipid deposition, 18 white plaques (growth stage) with lipid deposition, 11 yellow plaques without necrotic core (mature stage), and 12 yellow plaques with necrotic core (advanced mature stage) was 95, 92, 50, 27, and 25, respectively. By color fluorescent microscopy, TG deposited mostly in the fibrotic area of the plaques. Contrary to the general belief that TG amount increases with plaque maturation, the results indicated that TG was deposited in most of the normal coronary segments, but the amount decreased with plaque maturation. If 3-ANA becomes applicable clinically, the CFA system could be used for imaging TG within coronary plaques in patients in vivo.