Identifying Thin-Cap Fibroatheroma: Virtual-Histology Intravascular Ultrasound or Optical Coherence Tomography?

Leonardo Roever^*

Department of Clinical Research, Federal University of Uberlandia, Av. Para, 1720 - Bairro Umuarama Uberlandia -MG-CEP 38400-902, Brazil

*Corresponding Author:

Leonardo Roever
Department of Clinical Research
Federal University of Uberlandia, Av. Para 1720 - Bairro
Umuarama Uberlandia - MG - CEP 38400-902, Brazil
Tel: 553488039878
E-mail: leonardoroever@hotmail.com

Received Date: October 14, 2015 Accepted Date: October 15, 2015 Published Date: November 05, 2015

Citation: Roever L (2015) Identifying Thin-Cap Fibroatheroma: Virtual-Histology Intravascular Ultrasound or Optical Coherence Tomography?. Atheroscler open access 1:e105.

Copyright: © 2015 Roever L. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Atherosclerosis: Open Access

Introduction

Studies have shown that two-thirds of all myocardial infarctions are caused by the rupture of plaques with large lipid content and necrotic core (NC), resulting in luminal thrombosis [1-4]. Thin-cap fibroatheroma (TCFA) are characterized as a presence of a large lipid pool with overlying thin fibrous cap (<65 μm) and is associated with future major adverse cardiovascular events [5-7]. The diagnosis requires a high spatial resolution (axial, lateral, elevation) and temporal [8].

Virtual-histology intravascular ultrasound (VH-IVUS) is an invasive imaging modality which is used to identify plaque components, including NC, calcification, fibrous, and fibrofatty tissue (accuracies of >93.5% to characterize coronary plaque composition and a diagnostic accuracy of 76% for TCFA) [9-10]. Intravascular optical coherence tomography (OCT) allows plaque characterization using near-infrared light to display high-resolution (≈20 μm) images of coronary lesions (sensitivities around 75% for fibrous, 95% for fibrocalcific, and 92% for lipid-rich plaques)[11].

Brown and colleagues conducted a study in 258 regions of interest from autopsied human hearts, with plaque composition and classification assessed by histology and compared with coregistered ex vivo VH-IVUS and OCT. Sixty-seven regions of interest were classified as fibroatheroma on histology, with 22 meeting criteria for TCFA. On VH-IVUS, plaque (10.91 ± 4.82 versus 8.42 ± 4.57 mm²; P=0.01) and necrotic core areas (1.59 ± 0.99 versus 1.03 ± 0.85 mm²; P=0.02) were increased in TCFA versus other fibroatheroma. On OCT, although minimal fibrous cap thickness was similar (71.8 ± 44.1 μm versus 72.6 ± 32.4; P=0.30), the number of continuous frames with fibrous cap thickness ≤ 85 μm was higher in TCFA (6.5 [1.75-11.0] versus 2.0 [0.0-7.0]; P=0.03). Maximum lipid arc on OCT was an excellent discriminator of fibroatheroma (area under the ROC, 0.92; 95% CI, 0.87-0.97) and TCFA (area under the ROC, 0.86; 95% CI, 0.81-0.92), with lipid arc ≥ 80° the optimal cut-off value. The sensitivity, specificity, and diagnostic accuracy for TCFA identification was 63.6%, 78.1%, and 76.5% for VH-IVUS and 72.7%, 79.8%, and 79.0% for OCT. Combining VH-defined fibroatheroma and fibrous cap thickness ≤ 85 μm over 3 continuous frames improved TCFA identification, with diagnostic accuracy of 89.0% [11].

This study demonstrated that VH-IVUS and OCT can identify TCFA, although OCT accuracy may be improved using lipid arc ≥ 80° and fibrous cap thickness ≤ 85 μm over 3 continuous frames. Combined VH-IVUS/OCT imaging improved TCFA identification.

References

1. Virmani R, Kolodgie FD, Burke AP, Farb A, Schwartz SM (2000) Lessons from sudden coronary death: a comprehensive morphological classification scheme for atherosclerotic lesions. ArteriosclerThrombVascBiol 20: 1262-1275.
2. Tanaka A, Shimada K, Sano T, Namba M, Sakamoto T et al. (2005) Multiple plaque rupture and C-reactive protein in acute myocardial infarction.J Am CollCardiol 45: 1594-1599.
3. Rioufol G, Finet G, Ginon I, Andre-Fouet X, Rossi R, et al. (2002) Multiple atherosclerotic plaque rupture in acute coronary syndrome: a three-vessel intravascular ultrasound study. Circulation 106: 804-808.
4. Davies MJ, Thomas A (1984) Thrombosis and acute coronary-artery lesions in sudden cardiac ischemic death. N Engl J Med 310: 1137-1140.
5. Stone GW, Maehara A, Lansky AJ, de Bruyne B, Cristea E, et al. (2011) A prospective natural-history study of coronary atherosclerosis. N Engl J Med 364: 226-235.
6. Cheng JM, Garcia-Garcia HM, de Boer SP, Kardys I, Heo JH, et. Al. (2014) In vivo detection of high-risk coronary plaques by radiofrequency intravascular ultrasound and cardiovascular outcome: results of the ATHEROREMO-IVUS study. Eur Heart J 35: 639-647.
7. Calvert PA, Obaid DR, O’Sullivan M, Shapiro LM, McNab D, et. al. (2011) Association between IVUS findings and adverse outcomes in patients with coronary artery disease: the VIVA (VH-IVUS in Vulnerable Atherosclerosis) Study. JACC Cardiovasc Imaging 4: 894-901.
8. Virmani R, Burke AP, Kolodgie FD, Farb A (2002) Vulnerable plaque: the pathology of unstable coronary lesions. J IntervCardiol 15: 439-446.
9. Nair A, Margolis MP, Kuban BD, Vince DG (2007) Automated coronary plaque characterisation with intravascular ultrasound backscatter: ex vivo validation.EuroIntervention 3:113-120.
10. Obaid DR, Calvert PA, Gopalan D, Parker RA, Hoole SP, et al. (2013) Atherosclerotic plaque composition and classification identified by coronary computed tomography: assessment of computed tomography-generated plaque maps compared with virtual histology intravascular ultrasound and histology. CircCardiovasc Imaging 6: 655-664.
11. Brown AJ, Obaid DR, CostopoulosC, Parker RA, Calvert PA, et al. (2015) Direct Comparison of Virtual-Histology Intravascular Ultrasound and Optical Coherence Tomography Imaging for Identification of Thin-Cap Fibroatheroma. CircCardiovasc Imaging 8: e003487.