In this article, we analyze the influence of fluid dynamics variables on the development of obstructive coronary artery disease in the medium term after percutaneous coronary intervention with stent implantation. We have analyzed a group of seven patients and the study is focused on the mid-right coronary artery. In these patients we have studied the relationship between wall shear stress and arterial wall thickness both immediately after stent implantation and six months later. The realistic three-dimensional (3D) reconstruction of the arteries is performed with the data obtained with intravascular ultrasound (IVUS) and angiography. The commercial code Fluent is used to solve the Navier–Stokes equations. Special attention is paid to the shear stress on the wall arteries and the corresponding thickness. The results show that there is a negative correlation for most of the cases between the wall shear stress and increase in wall thickness. A model is proposed to study the instability at the wall, and qualitative agreement is found.