Impact of stent malapposition on intracoronary flow dynamics: An optical coherence tomography-based patient-specific study

Percutaneous coronary intervention with stent implantation has emerged as a popular approach to treat coronary artery stenosis. Stent malapposition (SM), also referred as incomplete stent apposition, could reduce stent tissue coverage and hence increase the risk of late stent thrombosis. The objective of this study was to investigate the impact of SM on intracoronary flow dynamics by combining optical coherence tomography (OCT) image-based model reconstruction and computational analysis. Firstly, a stenosed coronary artery model was reconstructed from OCT and angiography imaging data of a patient. Two structural analyses were carried out to simulate two types of coronary artery stent implantations: a fully-apposed (FA) case and a SM case. Then, based on the two deformed coronary geometries, two computational fluid dynamics (CFD) analyses were performed to evaluate the differences of hemodynamic metrics between the FA and the SM cases, including wall shear stress (WSS), time-averaged WSS (TWSS), oscillatory shear index (OSI), WSS gradient (WSSG), time-averaged WSSG (TWSSG), and relative residence time (RRT). The results indicated that maximum flow velocity was higher in the SM case than that of the FA case, due to the incomplete expansion of the stent and artery. Moreover, the SM case had a lower percentage of areas of adverse WSS ( 10/Pa) but a higher percentage of areas of adverse OSI (> 0.1) and WSSG (> 5000 Pa/m). Specifically, the differences of OSI, WSSG, and RRT between the two cases were relatively small. It was suggested that SM might not be responsible for negative hemodynamic metrics which would further result in stent thrombosis on the basis of the present specific model.