International Journal of Cardiology 270 (2018) 68–69
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International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Editorial
Hybrid invasive coronary imaging with intravascular ultrasound and optical coherence tomography: Informing research and guiding practice Laura Gatto a,b, Francesco Prati a,b, Giuseppe Biondi-Zoccai c,d,⁎, Arturo Giordano e,f a
Division of Cardiology, S. Giovanni-Addolorata Hospital, Rome, Italy Centro Per La Lotta Contro L'Infarto, Rome, Italy c Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy d Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli, Italy e Unità Operativa di Interventistica Cardiovascolare, Presidio Ospedaliero Pineta Grande, Castel Volturno, Italy f Unità Operativa di Emodinamica, Casa di Salute Santa Lucia, San Giuseppe Vesuviano, Italy b
a r t i c l e
i n f o
Article history: Received 27 June 2018 Accepted 3 July 2018 Available online 6 July 2018
If we knew what it was we were doing, it would not be called research, would it? [Albert Einstein] Coronary angiography is the gold standard for the assessment of coronary artery disease (CAD), but it simply shows coronary lumen [1]. Cardiovascular outcomes depend not only on luminal narrowing but also on plaque composition. Thus, great efforts have been made in developing new imaging modalities that may permit to better understand the pathophysiology of CAD, refine diagnosis, gauge prognosis, and guide decision making. Computed tomography (CT) has become the most feasible noninvasive imaging tool for CAD [2]. Furthermore, it is nowadays the only non-invasive imaging technique able to define the coronary wall, assessing plaques and evaluating atherosclerosis progression/regression [3]. Low-attenuation density at CT correctly identifies a lipid-rich core, however CT is still insufficient to recognize thin-cap fibroatheroma (TCFA). Plaque burden, positive remodeling and spotty calcifications represent traditional features of vulnerable plaques assessed by CT, but a new element, called napkin ring sign, has been identified. This refers to a thin ring-like rim of contrast enhancement surrounding the coronary plaque, mainly reflecting neovascularization through the vasa-vasorum with active inflammation, and it appears specific for the detection of a thin fibrous cap.
DOI of original article: https://doi.org/10.1016/j.ijcard.2018.05.117. ⁎ Corresponding author at: Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Corso della Repubblica 79, 04100 Latina, Italy. E-mail address:
[email protected] (G. Biondi-Zoccai).
https://doi.org/10.1016/j.ijcard.2018.07.027 0167-5273/© 2018 Elsevier B.V. All rights reserved.
Magnetic resonance imaging (MRI) is a promising tool, but its application was traditionally limited to larger arteries. Moreover, MRI, using ultra-small particles of iron oxide, is capable of identifying macrophages and it can be used for the serial assessment of the effects of lipidlowering therapy. Yet, this latter technique still plays an investigational role due to reduced spatial and temporal resolution, which limits routine clinical application [4]. Grey-scale intravascular ultrasound (IVUS) provides real-time, high resolution, tomographic images of the coronary tree. The detection of the lumen contours and the media–adventitia interface permits assessment of lumen and total vessel cross-sectional area and the estimation of plaque burden. In addition, it can define morphology, severity, and composition of atherosclerotic lesions. Radiofrequency analysis of ultrasonic signals (virtual histology [VH]-IVUS) permits further characterization of plaque features, which well correlates with histological analysis [5]. In a landmark study evaluating the natural history of atherosclerosis in acute coronary syndromes (ACS) [6], both culprit and non-culprit lesions were similarly responsible of major adverse cardiac events (MACE) over 3 years, with the important difference though that most non-culprit lesions latter causing events showed only a mild angiographic narrowing at baseline. A multivariate analysis based on VH-IVUS results, identified three independent predictors of MACE: plaque burden ≥70%, minimal luminal area ≤ 4.0 mm2 and the presence of TCFA, defined as a lipid-rich plaque with only a thin fibrous layer of intimal tissue covering the necrotic core. Optical coherence tomography (OCT), an imaging technique based on infrared light, is able to study atherosclerotic and stented segments with higher resolution than IVUS [7]. Therefore, OCT highlights important plaque elements as rupture, erosion, thrombus, lipid cores, calcium and calcific nodules; it can directly measure fibrous cap thickness and also allows better detection features of sub-optimal stenting (dissection, underexpansion, tissue/thrombus prolapse, strut malapposition/ uncoverage). Its major limitation is poor penetration: as the external elastic membrane of the vessel cannot usually be seen, it is not possible to assess true vessel size and plaque burden. Lipid-rich plaques show a specific chemical signature related to the presence of cholesterol esters. Ex-vivo studies also revealed the possibility of lipid identification using
Editorial
near-infrared spectroscopy (NIRS), a new imaging modality, presenting its data as a chemogram where the yellow regions are those with higher probability for the presence of lipid-core plaque (LCP). Although all these techniques provide a plethora of information, each presents specific limitations and to overcome these drawbacks hybrid (integration) imaging has been proposed. Fusion of IVUS and OCT represents indeed the ideal invasive imaging modality and can be done straightforwardly in the post-processing phase. Previous evidence suggests that the combined use of both techniques identifies more carefully high-risk plaques and is useful in planning and optimizing stent implantation [8]. Despite the obvious clinical and research significance of combined acquisition of IVUS and OCT, a hybrid catheter is not available yet clinically. Further improvements are mandatory before routine use, as existing catheters still have important limitations: large size, difficulties in the co-registration of both images, low image quality and slow image acquisition rate. The only hybrid intravascular imaging with widespread clinical uptake is IVUS-NIRS fusion through a new catheter housing a NIRS light source and an IVUS probe on its tip, allowing simultaneous image acquisition. Conversely, non-invasive fusion imaging modalities have already proved valuable not only in research but also in other clinical settings. For instance, the combination of angiographic data provided by CT and myocardial perfusion information given by scintigraphy can identify hemodynamically significant coronary stenoses and can be used to plan revascularization in patients with stable angina and multivessel disease [9]. Previous IVUS studies revealed that plaques with echo-signal attenuation (EA) might be related to deterioration of coronary flow after revascularization. In this issue of the Journal, Kimura et al. further contribute to the evidence base on the benefits of invasive hybrid coronary imaging by investigating the role of EA-plaques in stable and ACS patients, based on pre-intervention IVUS and OCT assessment in 609 coronary lesions [10]. Notably, EA-plaques found in subjects with stable angina showed less features of vulnerability and minor incidence of thrombus formation. These important results underline the significance of combined use of IVUS and OCT to better define differences in plaques vulnerability in various clinical settings and their effect on clinical outcomes, despite the difficulty to acquire both images for the increase in cost and procedural time. Therefore, further efforts are warranted in coming years to improve catheter design, opening new frontiers for hybrid invasive imaging technique. In addition, we can foresee in the future further hybrid imaging fusion efforts enabling the compilation
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of several data sources (e.g. coronary CT, myocardial perfusion scintigraphy, VH-IVUS and OCT) into a multidimensional synthesis capturing several patient features, as well as his/her correct diagnosis and precise prognosis. Conflicts of interest Prof. Biondi-Zoccai has consulted for Abbott and Bayer. References [1] P. Garrone, G. Biondi-Zoccai, I. Salvetti, N. Sina, I. Sheiban, P.R. Stella, P. Agostoni, Quantitative coronary angiography in the current era: principles and applications, J. Interv. Cardiol. 22 (2009) 527–536. [2] F. Nudi, M. Lotrionte, L.M. Biasucci, M. Peruzzi, A.G.M. Marullo, G. Frati, V. Valenti, A. Giordano, G. Biondi-Zoccai, Comparative safety and effectiveness of coronary computed tomography: systematic review and meta-analysis including 11 randomized controlled trials and 19,957 patients, Int. J. Cardiol. 222 (2016) 352–358. [3] F. D'Ascenzo, P. Agostoni, A. Abbate, D. Castagno, M.J. Lipinski, G.W. Vetrovec, G. Frati, D.G. Presutti, G. Quadri, C. Moretti, F. Gaita, G.B. Zoccai, Atherosclerotic coronary plaque regression and the risk of adverse cardiovascular events: a metaregression of randomized clinical trials, Atherosclerosis 226 (2013) 178–185. [4] T. Saam, T.S. Hatsukami, N. Takaya, B. Chu, H. Underhill, W.S. Kerwin, J. Cai, M.S. Ferguson, C. Yuan, The vulnerable, or high-risk, atherosclerotic plaque: noninvasive MR imaging for characterization and assessment, Radiology 244 (2007) 64–77. [5] G. Sangiorgi, F. Bedogni, P. Sganzerla, G. Binetti, L. Inglese, P. Musialek, G. Esposito, A. Cremonesi, G. Biasi, J. Jakala, A. Mauriello, G. Biondi-Zoccai, The Virtual histology In CaroTids Observational RegistrY (VICTORY) study: a European prospective registry to assess the feasibility and safety of intravascular ultrasound and virtual histology during carotid interventions, Int. J. Cardiol. 168 (2013) 2089–2093. [6] G.W. Stone, A. Maehara, A.J. Lansky, B. de Bruyne, E. Cristea, G.S. Mintz, R. Mehran, J. McPherson, N. Farhat, S.P. Marso, H. Parise, B. Templin, R. White, Z. Zhang, P.W. Serruys, PROSPECT Investigators, A prospective natural-history study of coronary atherosclerosis, N. Engl. J. Med. 364 (2011) 226–235. [7] F. Prati, S. Uemura, G. Souteyrand, R. Virmani, P. Motreff, L. Di Vito, G. Biondi-Zoccai, J. Halperin, V. Fuster, Y. Ozaki, J. Narula, OCT-based diagnosis and management of STEMI associated with intact fibrous cap, JACC Cardiovasc. Imaging 6 (2013) 283–287. [8] N. Gonzalo, H.M. Garcia-Garcia, E. Regar, P. Barlis, J. Wentzel, Y. Onuma, J. Ligthart, P.W. Serruys, In vivo assessment of high-risk coronary plaques at bifurcations with combined intravascular ultrasound and optical coherence tomography, JACC Cardiovasc. Imaging 2 (2009) 473–482. [9] F. Nudi, A.E. Iskandrian, O. Schillaci, M. Peruzzi, G. Frati, G. Biondi-Zoccai, Diagnostic accuracy of myocardial perfusion imaging with CZT technology: systemic review and meta-analysis of comparison with invasive coronary angiography, JACC Cardiovasc. Imaging 10 (2017) 787–794. [10] S. Kimura, T. Sugiyama, K. Hishikari, S. Nakagama, S. Nakamura, T. Misawa, M. Mizusawa, K. Hayasaka, Y. Yamakami, Y. Sagawa, K. Kojima, H. Ohtani, H. Hikita, A. Takahashi, The clinical significance of echo-attenuated plaque in stable angina pectoris compared with acute coronary syndromes: a combined intravascular ultrasound and optical coherence tomography study, Int. J. Cardiol. (2018) 1–6.
