Histomorphologic Assessment of the Internal Thoracic Artery in Patients Undergoing Coronary Artery Bypass Grafting: Impact of Smoking

Aim. To identify the age- and smoking-related histopathological changes in the internal thoracic artery (ITA) in patients with coronary artery disease (CAD). Materials and Methods. A histopathological study was performed on cross-sections of discarded distal segments of the left ITA obtained during coronary artery bypass grafting (CABG). The study included 38 patients with stable CAD aged 40-76 years (mean age 61.34±1.39 years), comprising 30 men and 8 women. Patients were divided into two age groups: Group I (n=16, <60 years) and Group II (n=22, ≥60 years). Subgroups IA (n=9; mean age 52.55±2.22 years) and IIA (n=7; mean age 65.85±1.58 years) comprised current smokers; subgroups IB (n=7; mean age 53.85±1.80 years) and IIB (n=15; mean age 68.0±1.07 years) comprised never-smokers. Results. Major risk factors for atherosclerosis were more frequent in subgroup IA compared to never-smokers of the same age (IB). Subgroup IA also demonstrated a significantly higher prevalence (p<0.05) of triple-vessel disease with coronary stenosis ≥75 % (100.0 %), alongside significantly higher mean SYNTAX (33.65±0.48 vs 19.64±2.12) and Gensini scores (134.22±15.82 vs 51.14±14.94) compared to IB. Patients in subgroup IA showed a significantly higher prevalence of intimal hyperplasia (p<0.05) and the highest mean intima-to-media ratio (1.23±0.32 vs 0.78±0.20, p<0.05). The most pronounced pathological changes across all ITA layers were observed in subgroup IA, including marked intimal thickening, fatty streaks and fibrous plaques, edema, delamination, medial and adventitial sclerosis, inflammatory infiltration of all vessel wall layers, and adventitial hemorrhages. Among patients aged over 60 years, smoking-related changes in the ITA followed a similar trend; however, their severity was less pronounced, which may be attributed to the confounding progression of age-related vascular remodeling. Conclusions. Smoking is associated with a more severe metabolic and comorbid profile, multivessel coronary artery disease, and advanced proatherogenic alterations within the internal thoracic artery wall. These pathological changes are most pronounced in patients with coronary artery disease under the age of 60.