Near-Infrared Spectroscopy Analysis of Coronary Chronic Total Occlusions

To examine the presence and localization of lipid-core plaque (LCP) in coronary vessels with chronic total occlusions (CTOs) using near-infrared spectroscopy (NIRS).

NIRS imaging was performed after guidewire crossing of the occlusion in 15 patients with CTOs. LCP was defined as ≥2 adjacent 2 mm yellow blocks on the block chemogram. We also measured the maximum lipid-core burden index (LCBI) in a 4 mm length of artery (maxLCBI4mm). Large LCP was defined as maxLCBI4mm ≥500.

Median patient age was 64 years (interquartile range [IQR], 61-67 years) and all patients were men with high prevalence of diabetes mellitus (64%) and prior coronary artery bypass graft surgery (27%). The CTO target vessel was the right coronary artery (46%), left anterior descending artery (27%), or circumflex artery (27%). Median occlusion length was 35 mm (IQR, 30-50 mm). LCP was present in 11 of 15 CTO vessels (73%) and a large LCP in 4 of 15 CTO vessels (27%). LCP was located at the proximal cap in 6 CTOs (55%), the CTO body in 6 CTOs (55%), and the distal cap in 2 CTOs (18%). The median overall LCBI and maxLCBI4mm were 145 (IQR, 79-243) and 415 (IQR, 267-505), respectively. All patients underwent successful stenting without any complications. The 12-month incidence of in-stent restenosis and target-lesion revascularization was 25%, and all patients who developed restenosis had an LCP at baseline.

LCPs are commonly encountered in coronary CTO vessels, suggesting an active intraplaque atherosclerotic process. The impact of LCP on postintervention outcomes requires further study.