Necrotic core and thin cap fibrous atheroma distribution in native coronary artery lesion-containing segments: a virtual histology intravascular ultrasound study.

OBJECTIVES: The aim of this study was to assess the longitudinal topographical relationships between minimal luminal area (MLA) sites and plaques with the most vulnerable characteristics using radiofrequency-based virtual histology intravascular ultrasound analysis.

METHODS: We analyzed 69 native coronary artery segments with de-novo lesions (>50% stenosis) obtained from 50 patients with ischemic coronary artery disease. Maximal necrotic core (maxNC) was defined as a virtual histology intravascular ultrasound frame with the maxNC area and virtual histology-characterized thin cap fibrous atheroma was defined as a cross-section, which contained a plaque burden of more than 40%, relative necrotic core area of 10% or more, and a narrow band encircling the lumen containing relative necrotic core area of more than 10%, in three consecutive frames.

RESULTS: MaxNC was present at the MLA site in only 17.4% of the segments, proximal in 52.2% (by 5.0 ± 5.4 mm), and distal to MLA in 30.4% (by 4.0 ± 5.1 mm). Non-MLA sites with maxNC (n=57) compared with MLA sites had reduced plaque burden (64.5 ± 11.2% vs. 76.0 ± 10.5%, P<0.001), increased remodeling index (1.04 ± 0.17 vs. 0.89 ± 0.15, P<0.001), less fibrotic tissue (47.7 ± 13.4% vs. 54.8 ± 13.8%, P<0.001), and higher dense calcium deposition (15.3 ± 10.8% vs. 11.9 ± 10.3%, P<0.001). Plaques containing maxNC and virtual histology-characterized thin cap fibrous atheroma were found in 23 of the non-MLA sites compared with two of the MLA sites (P<0.0001).

CONCLUSIONS: In coronary artery segments with intermediate-to-severe stenosis, plaques containing maxNC are mostly located away from the MLA site and more often comprise virtual histology-characterized thin cap fibrous atheroma. Such data may carry practical implications for coronary revascularization procedures.