Correlations Between the Contrast Density Gradient along the Coronary Stents and Functional Significance of In-stent Restenosis

Introduction: Coronary artery disease (CAD) is the leading cause of death worldwide and is associated with a significant socio-economic impact. In many cases, patients are treated with implanted coronary stents that carry a significant risk for reobstruction. The aim of our study was to evaluate the importance of coronary computed tomography angiography (CCTA) in evaluating the significance of in-stent restenosis lesions and for establishing the indication for reintervention in these cases.

Materials and methods: We evaluated 25 patients who underwent CCTA examination. We determined the contrast density, expressed in Hounsfield units at two levels, proximal and distal to the stent.

Results: There were no statistically significant differences between the study groups in terms of gender (41.17% females in Group 1 vs. 37.5% in Group 2, p = 1), presence of hypertension (41.17% in Group 1 vs. 62.5% in Group 2, p = 0.31), smoking status (41.17% in Group 1 vs. 37.5% in Group 2, p = 0.31), incidence of dyslipidemia (47.05% vs. 50%, p = 1) and diabetes mellitus (35.29% vs. 0%, p = 0.31). However, the age of the study population was significantly higher in the groups with significant ISR (58.94 ± 8.35 vs. 47.25 ± 11.2, p = 0.02). Patients who showed significant angiographic in-stent stenosis (more than 70%) were found to have a higher transluminal attenuation gradient, compared with those with less severe lesions (14.5 ± 5.4 vs. 5.14 ± 2.4, p = 0.02).

Conclusions: The transluminal attenuation gradient, assessed by CCTA is a non-invasive-derived parameter that can help the clinician to determine the right time for revascularization in case of in-stent restenosis.