The effect of coronary artery plaque composition, morphology and burden on Absorb bioresorbable vascular scaffold expansion and eccentricity — A detailed analysis with optical coherence tomography
Introduction
Percutaneous coronary intervention (PCI) has evolved in recent decades with the use of bare metal stents (BMS) to drug eluting stents (DES) [1] and most recently bioresorbable scaffolds (BVS). The Absorb BVS (Abbott Vascular, Santa Clara, USA) consists of a semi-crystalline poly-l-lactide backbone coated with the anti-proliferative agent, everolimus [2]. The poly-l-lactide backbone is progressively degraded by hydrolysis from 6 to 12 months and is fully resorbed after 2 years [3].
Metallic stent expansion parameters such as eccentricity and symmetry have a known association with adverse clinical outcomes [4], [5]. In the MUSIC trial, the use of intravascular ultrasound (IVUS) demonstrated that the set criteria (stent apposition, stent minimal lumen area ≥ 90% of average reference lumen area, eccentricity index ≥ 0.7) were correlated with favourable clinical and angiographic outcomes [6].
Assessment of lumen geometry, plaque composition, morphology and burden has markedly advanced in recent times with the advent of intravascular optical coherence tomography (OCT). OCT is a light-based imaging modality that provides high-resolution cross-sectional images of the coronary vasculature. It has high axial (10 μm) and lateral resolutions (20–40 μm) [7], allowing for unprecedented diagnostic imaging detail of the coronary vasculature during PCI [8]. OCT differentiates tissue characteristics based on polarisation properties of light and permits precise measurements of plaque morphology, composition and burden within the coronary arteries [8], [9], [10], [11].
Due to its unique design, BVS has different expansion characteristics compared with metallic stents and thus knowledge from metallic stents cannot be transferred directly to BVS. It has previously been demonstrated that appropriate BVS deployment is related to angiographic assessment of maximal lumen diameter prior to the implantation [12]. However, there is currently limited information regarding BVS expansion characteristics with respect to coronary plaque burden. Therefore we sought to evaluate the effect of coronary plaque composition, morphology and burden on Absorb BVS expansion using OCT.
Section snippets
Study design and patient population
Seventeen consecutive patients undergoing OCT-guided BVS implantation from August 2012 to March 2013, at the Royal North Shore Hospital were reviewed. All BVS case data were entered prospectively into a local database, based on a predetermined data set. This included information on patient demographics, risk factors, and outcome measures. All information was entered by the operator at the time of the index procedure and cross-checked and updated by an independent audit officer at the end of the
Statistics
The relationship between each plaque characteristic and scaffold expansion and scaffold eccentricity index was analysed by a repeated measures ANOVA to take into account repeated measures on each scaffold analysed. Statistical significance was accepted as p < 0.05. SAS version 9.3 (SAS Institute Inc., Cary, NC, USA) was used for all statistical analyses.
Patient demographics and procedural data
Two thousand three hundred and thirty four OCT cross-section frames totalling 462.6 mm of BVS were analysed in 17 patients with unstable angina pectoris who underwent OCT-guided BVS implantation. Patient demographics and procedural data can be seen in Table 1. A total of 20 BVS were implanted. The mean subject age was 50.2 years with a SD of 11.7 years. Fourteen (82%) were males, 13 (76%) patients were dyslipidemic, 9 (53%) were hypertensive, 4 (24%) were current smokers and 3 (18%) were diabetic.
Results
Greater calcific plaque burden as represented by greater CP area (mean SEI 78.9% vs. average SEI 80.0%, p < 0.05), thicker CP (78.5% vs. 80.4%) and CP closer to the lumen (78.3% vs. 80.2%, p < 0.001) significantly correlated with a reduced BVS expansion for each cross section analysed within the coronary vasculature (Fig. 2). The correlation was maintained even after CP thickness was adjusted for using the underlying target vessel size (78.5% vs. 80.4%, p < 0.001). However, the correlation was no
Discussion
A number of different forces may affect coronary BVS deployment. These include transmitted forces from non-diseased sections of the coronary artery, the elastic recoil of the diseased segment, as well as atheromatous lesion characteristics.
Thus, in order to obtain optimal BVS implantation it is crucial to understand these aspects, in particular how individual lesion characteristics may play a role. Underlying coronary atheromatous lesions have a number of different characteristics and our study
Limitations
Although OCT has many benefits for in-vivo assessment of the coronary vasculature, it also has some limitations. In-order to have adequate OCT pullbacks for analysis, blood within the vessel lumen needs to be purged prior to imaging. This makes assessment of long vessel segments with a single pullback difficult as residual blood attenuates the light penetration and may create suboptimal imaging for lumen border and coronary vasculature delineation [22]. Eccentric wire position in the lumen can
Conclusion
The current study is one of the first to study plaque burden and its effect on BVS expansion characteristics. BVS expansion and eccentricity are significantly impacted by plaque composition, morphology and burden. Although significant associations between plaque burden and BVS expansion characteristics were demonstrated, the clinical significance of these findings is unknown. Further research into this area to examine the clinical significance on cardiovascular outcomes is needed.
Disclosures
Associate Professor Ravinay Bhindi was supported by Heart Research Australia, Sydney, Australia. Associate Professor Gemma Figtree was supported by Sydney Medical Foundation, Sydney Australia. All other authors have reported that they have no relationships to disclose.
References (23)
- et al.
Evaluation of the second generation of a bioresorbable everolimus-eluting vascular scaffold for the treatment of de novo coronary artery stenosis: 12-month clinical and imaging outcomes
J. Am. Coll. Cardiol.
(2011) - et al.
Local determinants of thrombus formation following sirolimus-eluting stent implantation assessed by optical coherence tomography
J. Am. Coll. Cardiol. Intv.
(2009) - et al.
Stent underexpansion and residual reference segment stenosis are related to stent thrombosis after sirolimus-eluting stent implantation: an intravascular ultrasound study
J. Am. Coll. Cardiol.
(2005) - et al.
Intravascular optical imaging technology for investigating the coronary artery
J. Am. Coll. Cardiol. Img.
(2011) - et al.
Diagnostic accuracy of optical coherence tomography and integrated backscatter intravascular ultrasound images for tissue characterization of human coronary plaques
J. Am. Coll. Cardiol.
(2006) - et al.
Assessment of coronary arterial plaque by optical coherence tomography
Am. J. Cardiol.
(2006) - et al.
Stent thrombosis with drug-eluting stents: is the paradigm shifting?
J. Am. Coll. Cardiol.
(2013) - et al.
Treatment of a left anterior descending artery chronic total occlusion using a bio-absorbable scaffold, utilising optical coherence tomography
Int. J. Cardiol.
(2013) - et al.
Visualization of coronary atherosclerotic plaques in patients using optical coherence tomography: comparison with intravascular ultrasound
J. Am. Coll. Cardiol.
(2002) - et al.
The race to achieve the gold standard in coronary imaging
Rev. Esp. Cardiol.
(2009)
Recent progress in percutaneous coronary intervention: evolution of the drug-eluting stents, focus on the XIENCE V drug-eluting stent
Coron. Artery Dis.
Cited by (17)
Spreading New (OCT-)Light on Bioresorbable Vascular Scaffolds' Performance. Can the Future of BRS Become Brighter?
2019, Cardiovascular Revascularization MedicineEffect of Plaque Composition, Morphology, and Burden on DESolve Novolimus-Eluting Bioresorbable Vascular Scaffold Expansion and Eccentricity — An Optical Coherence Tomography Analysis
2019, Cardiovascular Revascularization MedicineCitation Excerpt :The preparation and post-BRS-deployment management in the aforementioned study by Shaw et al. [8] was not detailed; therefore, the diverging results could be explained by different methods of lesion preparation. This would indicate that a careful pre-dilatation can overcome the negative impact of CP plaque burden on the BRS implantation result, taking into consideration that only the median CP arc angle but not CP area, CP thickness, or CP depth is slightly smaller in our cohort compared with the patients studied by Shaw et al. [8]. A second aspect that might account for the different results may be the different BRS device used.
Final shape of biovascular scaffolds and clinical outcome. Results from a multicenter all-comers study with intravascular imaging
2017, International Journal of CardiologyIs bioresorbable vascular scaffold acute recoil affected by baseline renal function and scaffold selection?
2016, International Journal of CardiologyCitation Excerpt :Furthermore, in contrast with metal stents aggressive post-dilatation can lead scaffold fractures in BVS use [19]. Shaw et al. demonstrated that BVS expansion and eccentricity were highly affected by plaque composition, morphology and burden; consequently lower scaffold eccentricity index and scaffold expansion index are associated with greater calcified plaque area and thickness [4]. Patients with RI have more complex and advanced coronary artery disease, hence a higher peri-procedural risk for PCI [11].
Optical coherence tomography assessment of incidence, morphological characteristics, and spontaneous healing course of edge dissections following percutaneous coronary intervention with stent implantation in patients with non-ST segment elevation myocardial infarction
2016, International Journal of CardiologyDoes Asymmetric Expansion of Bioresorbable Vascular Scaffolds Cause Stent Failure?∗
2016, JACC: Cardiovascular Interventions