Comparative Histopathology of Radial Artery Versus Internal Thoracic Artery and Risk Factors for Development of Intimal Hyperplasia and Atherosclerosis

BACKGROUND: In this study, we examined the comparative histopathology, morphometry, and risk factors for the development of intimal hyperplasia and atherosclerosis in the radial artery (RA) and the internal thoracic artery (ITA). METHODS AND RESULTS: Paired specimens of RAs and ITAs, obtained from 150 patients who underwent CABG, were evaluated with histopathology; 110 pairs of arteries were suitable for morphometric analysis. The severity of disease was evaluated on the basis of percentage of luminal narrowing, intimal thickness index, and intima-to-media ratio. Risk factors were determined with stepwise linear regression. Intimal hyperplasia was seen in 141 RAs (94%) and 103 ITAs (69%) (P<0.001). Atherosclerosis was seen in 5% of RAs and 0.7% of ITAs (P=0.04). Medial calcification was found only in RAs (20 of 150, 13.3%) (P<0.001). Morphometric analysis showed that compared with ITAs, RAs had a significantly higher intimal area, medial area, percentage of luminal narrowing, intimal thickness index, and intima-to-media ratio (all P<0.001) Factors found to be significant (P<0.05) predictors of the 3 severity indices of intimal hyperplasia, including atherosclerosis, in RAs were peripheral vascular disease, smoking, age, and diabetes. Risk factors for intimal hyperplasia in ITAs were age and smoking. CONCLUSIONS: The RA is more likely to have atherosclerosis, intimal hyperplasia, and medial calcification than the ITA. Morphometric analysis indices showed marked differences between the RA and the ITA. Care should be taken when selecting the RA as a conduit in CABG, particularly in patients who are elderly, diabetic, smoke, or have peripheral vascular disease.