Mid-term structural change in the radial artery grafts after coronary artery bypass grafting

Background. Currently, excellent patency rates of radial artery grafts for coronary artery bypass grafting in the early period have been reported. However, the long-term result of radial artery grafts remains unclear. We investigated the midterm structural change in radial artery grafts using intravascular ultrasound imaging (IVUS). Methods. IVUS studies were performed on 15 radial artery grafts in the early phase and 11 in the midterm phase (20.3 ± 13. 7 days and 37.6 ± 7.2 months after surgery, respectively). The radial artery grafts were observed throughout the entire length and 10 cross-sectional images were selected from each graft for measurement of the thickness of the intima (IN) and intima-plus-media (IN + MD). Grafts having palpable arteriosclerosis at the time of harvesting were excluded. IN and IN + MD were compared between the early and midterm phases using repeated measures analysis of variance. The coefficient of variation of IN and IN + MD was calculated as an index of irregularity and compared between the phases. Results. IVUS revealed uniform and thin intima and media in the early and midterm groups and IVUS images were similar between the groups. There was no significant difference in both IN and IN + MD between the groups (IN, p = 0.83; IN + MD, p = 0.55). The median of coefficient of variation of IN and IN + MD was 8.5% and 8.1% in the early group and 8.7% and 9.3% in the midterm group. Again, there was no significant difference between the groups (IN, p = 0.87; IN + MD, p = 0.27). Conclusions. The present study suggested that structural changes rarely developed in radial artery grafts over several years after surgery.