Intravascular Ultrasound and Near-Infrared Spectroscopic Characterization of Thin-Cap Fibroatheroma

Thin-cap fibroatheromas (TCFAs) are considered precursors for plaque rupture and subsequent acute coronary events. We investigated intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) characteristics of lesions that were histopathologic TCFAs. IVUS, NIRS, and histopathology were performed in 271 atherosclerotic lesions from 107 fresh coronary arteries from 54 patients at necropsy. The plaque burden and remodeling index calculated by IVUS and maximum lipid core burden index within any 4-mm segment (maxLCBI4mm) calculated by NIRS were compared among each plaque type based on histopathologic classifications but focusing on TCFA. Lesions classified as TCFAs had the largest plaque burden, the highest remodeling index, and the greatest maxLCBI4mm. Plaque burden ≥69% (90% sensitivity, 75% specificity, and area under the curve 0.87); remodeling index ≥1.07 (80% sensitivity, 79% specificity, and area under the curve 0.84); and maxLCBI4mm ≥323 (80% sensitivity, 85% specificity, and area under the curve 0.84) predicted a histopathologic TCFA. In conclusion, a large plaque burden and a high remodeling index assessed by IVUS and lipid-rich plaque determined by the NIRS maxLCBI4mm are useful predictive markers of TCFA.