Abstract 12775: The Impact of Spotty Calcification on Microstructures Within Thin-cap Fibroatheromas: Frequency Domain Optical Coherence Tomography Analysis
Background: Thin-cap fibroatheroma (TCFA) is a vulnerable plaque phenotype, typically not heavily calcified. Small amounts of calcium in a spotty distribution have been reported as a morphological characteristic of unstable lesions. The relationship between spotty calcification and features of vulnerable plaques has not been characterized.
Methods: We analyzed 210 non-culprit lipid plaques (TCFA/non-TCFA: 105/105) in 111 patients with stable coronary artery disease by using frequency domain optical coherence tomography (FD-OCT). TCFA was defined as a lipid-rich plaque with fibrous cap thickness ≤ 65 um at the thinnest part on a cross-sectional image. Spotty calcification was defined as the presence of lesions ≤4mm in length and containing an arc of calcification ≤90°. We calculated lipid index in each TCFA by multiplying the mean lipid arc and lipid length. FD-OCT-derived plaque microstructures were compared in TCFA with and without spotty calcification.
Results: The prevalence of spotty calcification was significantly higher in TCFA compared to non-TCFA (42 v. 27%, p≤0.01). Patients with TCFA containing spotty calcification were less likely to be obese (p=0.01) and have lower prevalence of optimal LDL-C (p≤0.05) and HDL-C (p≤0.05) than non-TCFA patients. FD-OCT demonstrated that the presence of spotty calcification within TCFA had larger lipid index (p≤0.01) and higher prevalence of cholesterol crystal (p≤0.01). Additionally, the increasing number of spotty calcification within TCFA was positively correlated to lipid index (r2=0.06, p≤0.01) and cholesterol crystal (r2=0.07, p≤0.01). Fibrous cap thickness and the prevalence of microchannel were similar in TCFA with and without spotty calcification.
Conclusions: Spotty calcification was observed in over 40% of TCFA. This plaque phenotype indicates greater plaque vulnerability, reflected by large lipid core and frequent cholesterol crystallization.
- © 2013 by American Heart Association, Inc.