In-vivo detection of the frequency and distribution of thin-cap fibroatheroma and ruptured plaques in patients with coronary artery disease: an optical coherence tomographic study.

Objectives: The purpose of this study was to assess the prevalence and to quantify the thin-cap fibroatheroma (TCFA) and ruptured plaques in patients with coronary artery disease using optical coherence tomography (OCT).

Background: TCFA lesions are the most prevalent precursors of plaque rupture, and are responsible for acute coronary syndromes (ACS). There are limited data regarding the frequency and distribution of TCFA in diseased coronary arteries.

Methods: Coronary artery OCT was performed in 78 vessels in 47 patients, with stable angina (SA) or ACS. OCT plaque characteristics were derived using criteria that had been validated earlier. TCFA was defined as rich in lipid (two or more quadrants) with thin fibrous cap (<65 μm). Comparison was made between SA and unstable angina, and culprit and nonculprit vessels.

Results: There was a higher incidence of TCFA and plaque rupture (65 vs. 24%, P=0.003, and 40 vs. 15%, P=0.04) in ACS patients. This was reflected in a higher lipid pool (2.66 vs. 2.26 quadrants, P=0.04) and minimum fibrous cap thickness (52 vs. 74 μm, P=0.001) in ACS patients. The mean numbers of TCFA (2.5) were similar in patients with SA and ACS. However, the maximal length of TCFA (2.63 vs. 5.54 mm, P=0.026) and plaque rupture sites (P=0.046) were higher in ACS vessels. No relationship was found between baseline characteristics and TCFA incidence and plaque rupture. We identified ACS (P=0.002), higher mean lipid pool (P=0.002), longer TCFA length (P=0.007) and higher number of TCFA (P=0.02) as predictors of plaque rupture sites.

Conclusion: In this in-vivo study, we identified a higher incidence of longer TCFAs and plaque rupture sites associated with ACS.