| Background: A calcified nodule is a suspected type of vulnerable plaque accounting for approximately 3% of coronary events. Because 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% in calcified nodule vs 9.7 % in non-nodular calcium, p<0.001), (2) convex shape of luminal side of calcium (100% vs 16.0 %, p<0.001), (3) irregular luminal surface (64.7% vs 11.6%, p<0.001), and (4) irregular superficial surface (leading edge) of calcium (88.2% vs 19.0%, p<0.001). 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. Conclusion: Calcified nodules have distinct IVUS features (irregular and convex luminal surface) and contain minimal lipid core by NIRS, permitting their prospective identification in vivo. Background: Pathologic studies suggest that calcified coronary nodules are a rare cause of thrombotic events. The frequency, distribution, predictors, and outcomes of calcified nodules detected in vivo have never been described.Methods: Following successful stenting in 697 patients (167 female, median age of 58.1 years) with acute coronary syndromes (ACS), three-vessel grayscale and virtual histology (VH) intravascular ultrasound (IVUS) was performed in the proximal-mid segments of all three coronary arteries as part of a prospective, multicenter study. Based on recent histologic validation, an independent core lab identified calcified nodules as distinct calcification with an irregular, protruding and convex luminal surface. Patients were followed for (median) three years.Results: Overall, 314 calcified nodules were detected in 250 of 1573 analyzable arteries (185 of 623 patients). Thus, the prevalence of calcified nodules was 17% per artery and 30% per patient. Two or more calcified nodules were detected in 48 coronary arteries (3%) in 76 patients (12%). The location of the calcified nodules were <40mm of the ostium of the coronary artery in 85% of LAD and 86% of LCX while calcified nodules within the RCA were evenly and more distally distributed. Patients with calcified nodules were significantly older, had more plaque volume, and more thick-cap fibroatheroma, but fewer non-culprit lesion major adverse events on follow-up.Conclusion: Calcified nodules in untreated non-culprit coronary segments in patients with ACS are more prevalent than previously recognized; their distribution mirrors the origin of most thrombotic events (proximal LAD and LCX and throughout the RCA). However, calcified nodules caused fewer non-culprit lesion major adverse events during 3-years of follow-up. |
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