Date Published: January 25, 2019
Publisher: Public Library of Science
Author(s): Diogo A. Fonseca, Pedro E. Antunes, Manuel J. Antunes, Maria Dulce Cotrim, Carmine Pizzi.
In this study, we aimed at performing a histomorphometric analysis of human left internal thoracic artery (ITA) samples as well as at correlating the histomorphometric findings with the clinical profile, including risk factors and medication. Distal segments of ITA were obtained from 54 patients undergoing coronary artery bypass grafting. Histological observation was performed in paraffin-embedded transverse sections of ITA through four staining protocols: hematoxylin-eosin, van Gieson, Masson’s trichrome and von Kossa. Morphometric analysis included the intimal width (IW), medial width (MW) and intima/media ratio (IMR). No overt atherosclerotic lesions were observed. Mild calcifications were observed across the vascular wall layers in almost all samples. Multivariable linear regression analysis showed associations between IW and IMR and the following clinical variables: age, gender, kidney function expressed as eGFR and myocardial infarction history. Age (odds ratio = 1.16, P = 0.004), female gender (odds ratio = 11.34, P = 0.011), eGFR (odds ratio = 1.03, P = 0.059) and myocardial infarction history (odds ratio = 4.81, P = 0.040) were identified as the main clinical predictors for intimal hyperplasia. Preatherosclerotic lesions in ITA samples from patients undergoing coronary revascularization were associated not only with classical cardiovascular risk factors such as age and gender, but also with other clinical variables, namely kidney function and myocardial infarction history.
Vascular structural changes have been associated with cardiovascular diseases . In particular, carotid intima-media thickness (IMT) is associated with risk factors  and is an independent predictor for cardiovascular outcomes [1, 3–5]. Furthermore, Iwamoto et al.  suggested the use of the brachial IMT as a marker for the atherosclerosis grade. In this study, the authors also showed that increased brachial IMT was associated with decreased flow-mediated dilation, thus suggesting a strong connection between the structural and functional properties of the vascular system.
Due to a higher functional and structural integrity, the human ITA has been recognized as a special vessel, which has been used in a wide array of studies, including as a model to study vascular physiology. Despite being considered an atherosclerosis-resistant vessel, several studies have emerged showing structural changes from intimal hyperplasia to overt atherosclerotic lesions, as previously reviewed by us . Although distinct evidence has emerged regarding the relationship with risk factors, risk factors such as age [21, 22], arterial hypertension , diabetes mellitus , smoking  and chronic kidney disease  have been associated with structural changes such as intimal or medial thickening, increased IMR and/or others.