Abstract 21455: Histolopathologic Validation of Intravascular Ultrasound Diagnosis of a Calcified Coronary Nodule, a Type of Plaque Suspected to be Vulnerable
Background: Calcified nodule is a suspected type of vulnerable plaque, accounting for approximately 3% of coronary events although its intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) features have never been validated. We assessed IVUS and NIRS characteristics of calcified nodules in comparison with histopathology.
Methods: IVUS and NIRS were performed in 856 pathologic slices in 41 coronary artery segments (13 LAD, 5 LCX, 23 RCA) in 18 autopsy hearts. Pathologic sections were analyzed every 2mm; qualitative and quantitative findings of matched IVUS and NIRS were analyzed.
Results: IVUS detected calcification in 285 frames;17 (6.0%) were calcified nodules and 268 (94.0%) were non-nodular calcium by histopathology Two (11.8%) calcified nodules were solitary and 15 (88.2%) were adjacent to non-nodular calcium. IVUS characteristics of calcified nodules were (1) convex shape of luminal surface (94.1% vs 9.7 % in non-nodular calcium, p<0.001) and (2) irregular luminal surface (64.7% vs 11.6% in non-nodular calcium, p<0.001) (Figure). 64.7% of calcified nodules were located distal to the minimum lumen area (MLA) site and the rest proximal to the MLA site (distance 9.1±8.7mm), but none at the MLA site. Lumen area at the calcified nodule site was larger (6.2±2.4 vs 4.3±1.6mm2, p<0.001) and plaque burden less (57±6 vs 68±5 %, p<0.001) than at the MLA site. NIRS showed minimal lipid core plaque at calcified nodule sites compared to reference fibroatheromas (Table) .
Conclusions: Calcified nodules contain minimal lipid core by NIRS and have distinct IVUS features (irregular and convex luminal surface), permitting their prospective identification in vivo.
- © 2010 by American Heart Association, Inc.