Post-implantation shear stress assessment: an emerging tool for differentiation of bioresorbable scaffolds

Erhan Tenekecioglu,Taku Asano,Ply Chichareon,Rasha Al-Lamee,Robert Van Geuns,Kerem Pekkan,Patrick W Serruys,Johan H C Reiber,Rodrigo Modolo,Yuki Katagiri,Yosuke Miyazaki,Ryo Torii,Kuniaki Takahashi,Yoshinobu Onuma,Carlos Colet,Christos V Bourantas,Kadem Al-Lamee

doi:10.1007/s10554-018-1481-3

Abstract

Optical coherence tomography based computational flow dynamic (CFD) modeling provides detailed information about the local flow behavior in stented/scaffolded vessel segments. Our aim is to investigate the in-vivo effect of strut thickness and strut protrusion on endothelial wall shear stress (ESS) distribution in ArterioSorb Absorbable Drug-Eluting Scaffold (ArterioSorb) and Absorb everolimus-eluting Bioresorbable Vascular Scaffold (Absorb) devices that struts with similar morphology (quadratic structure) but different thickness. In three animals, six coronary arteries were treated with ArterioSorb. At different six animals, six coronary arteries were treated with Absorb. Following three-dimensional(3D) reconstruction of the coronary arteries, Newtonian steady flow simulation was performed and the ESS were estimated. Mixed effects models were used to compare ESS distribution in the two devices. There were 4591 struts in the analyzed 477 cross-sections in Absorb (strut thickness = 157 µm) and 3105 struts in 429 cross-sections in ArterioSorb (strut thickness = 95 µm) for the protrusion analysis. In cross-section level analysis, there was significant difference between the scaffolds in the protrusion distances. The protrusion was higher in Absorb (97% of the strut thickness) than in ArterioSorb (88% of the strut thickness). ESS was significantly higher in ArterioSorb (1.52 ± 0.34 Pa) than in Absorb (0.73 ± 2.19 Pa) (p = 0.001). Low- and very-low ESS data were seen more often in Absorb than in ArterioSorb. ArterioSorb is associated with a more favorable ESS distribution compared to the Absorb. These differences should be attributed to different strut thickness/strut protrusion that has significant effect on shear stress distribution.

Highlights

As a promising technology, bioresorbable scaffolds (BRS) introduced new terms such as degradation, disappearance and recovery in vasomotricity, into the interventionalists’ jargon
In Optical coherence tomography (OCT), in the device level analysis in-scaffold mean lumen area were comparable in the two scaffold groups
In the cross-section level analysis, in-scaffold mean lumen area was slightly higher in Absorb (7.62 ± 1.10 mm2) compared with the ArterioSorb (7.35 ± 0.86 mm2) (p = 0.052) (Table 4)

Summary

Introduction

Bioresorbable scaffolds (BRS) introduced new terms such as degradation, disappearance and recovery in vasomotricity, into the interventionalists’ jargon. Relatively high thrombosis events have been a serious setback in the development of this technology and jeopardized the change in the paradigm in percutaneous coronary revascularization [1, 2]. In the era of metallic DES, beside the implantation techniques, the stent design and strut thickness were deemed responsible for the adverse events [3, 4]. Stent/scaffold implantation creates a new endoluminal surface with near-wall blood flow interference that have major mechano-transduction impact [5]. In instrumented vessel segments disturb the blood flow in relation to the scaffold design, strut geometry and strut thickness [6, 7]. While laminar and relatively high shear stress is athero-protective and holds the platelets and endothelium quiescent, low and oscillatory shear stress upregulates inflammatory oxidative reactions, can induce thrombus formation, promote reactive neointima and subject the vessel wall to atherosclerotic changes [8, 9]

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