Coronary artery stretch versus deep injury in the development of in-stent neointima

Abstract

Objective: To investigate the relative importance of stent induced arterial stretch and deep injury to the development of in-stent neointima. Setting: Normal porcine coronary arteries Methods: 30 BiodivYsio stents (Biocompatibles) were deployed at a stent to artery ratio of 1.25:1 (a moderate injury) and harvested at 28 days. Multiple serial cross sections were analysed morphometrically and the neointimal areas were correlated with the type and degree of injury. Results: Arterial stretch occurred in 78% of struts (77% of sections) and produced moderate neointimal growth (neointimal area 1.93 (0.13) mm 2 ). Deep injury (rupture of the internal elastic lamina) occurred in 20% of struts (23% of sections) and produced a 1.7-fold increase in neointimal area (3.33 (0.41) mm 2 ) compared with stretch only (p = 0.0002). With even deeper injury (rupture of the external elastic lamina), there was a 2.6-fold increase in neointimal area (5.01 (0.48) mm 2 ) compared with stretch only (p = 0.02). A new injury score, incorporating both stretch and deep injury, correlated with neointimal area (r = 0.60, p < 0.001). Conclusions: Stretch of the coronary artery in a stent is common, and a major contributor to neointima formation, even in the absence of deep injury. Deep injury is, however, a more potent stimulus to neointima formation than stretch. Greater degrees of stretch are associated with thicker neointima. Where neither deep injury nor stretch are seen, the stent has no effect upon the development of neointima. Stents are now used in more than 70% of percutaneous coronary interventions. In-stent restenosis is important because it is common and difficult to treat. It is known from intravascular ultrasound (IVUS) studies that in-stent dimensions and stent length are the main predictors of in-stent restenosis.

Angiographic Restenosis After Myocardial Bridge Stenting: A Comparative Study With Direct Stenting of De-Novo Atherosclerotic Lesions

“…[19][20][21] It is not clear how much the underlying atherosclerotic plaques contribute to in-stent restenosis, but both the deep injury and the vessel stretch were shown to trigger the development of in-stent neointima in even normal coronary arteries. 22) Although maximum deployment pressures were not different between the two groups, an additional external force on the vessel wall might have caused a deeper injury in the MB group. Furthermore, the persistence of external compression in MB constitutes an important difference between two groups.…”

Sequential Structural and Fluid Dynamics Analysis of Balloon-Expandable Coronary Stents: A Multivariable Statistical Analysis

“…7,22,23,32,35,46,77,81,82,86 The mechanical impact of the investigated stents was evaluated in terms of the equivalent von Mises stress (ES) distribution predicted in the artery wall. The ES is calculated as follows:…”

“…Over the past two decades, several clinical studies have identified strong correlations between neointimal hyperplasia following coronary stent deployment and both stent-induced arterial injury 7,22,23,32,35,46,77,81,82,86 and altered vessel hemodynamics. 6,17,18,20,21,52,71,79,88 In light of these observations, a significant body of research has been carried out in this area.…”

Computational analysis of mechanical stress–strain interaction of a bioresorbable scaffold with blood vessel

“…In truth, the damage of the internal elastic lamina (border between intima and media) or external elastic lamina (border between media and adventitia) has been strongly correlated with neointimal growth. This deep injury concept points to media and adventitia (Gunn et al, 2002). The expansion of a stent within an eccentric artery induced considerably higher stresses in these two vessel layers.…”