Heavy metal ions can cause allergic and inflammatory reactions that might be associated with in-stent restenosis. This randomized multicenter clinical study was designed to determine if carbon ion–implanted stents reduce luminal late loss by blocking heavy metal ion diffusion into the surrounding tissue.

A total of 225 patients with 230 native coronary lesions were randomly assigned to receive either a carbon ion–implanted Arthos^Inert stent (group 1, n = 113) or a bare metal Arthos stent (group 2, n = 117). The primary endpoint was in-stent luminal late loss at 6-month angiographic follow-up, and the secondary endpoints were the 6-month angiographic restenosis rate and the occurrence of the major adverse cardiac events (MACE) including death, nonfatal myocardial infarction, and target lesion revascularization at 12 months.

The baseline characteristics were similar in the 2 groups. In-hospital events did not occur in any patients. Angiographic follow-up at 6 months was obtained in 184 lesions (80%). At follow-up, the luminal late loss was similar in the 2 groups (0.91 ± 0.77 mm in group 1 vs 0.88 ± 0.80 mm in group 2, P = .79), and the angiographic restenosis rates were 11.0% in group 1 and 16.1% in group 2 (P = .31). The occurrence rates of MACE at 12 months were 9.1% in group 1 and 10.4% in group 2 (P = .73).

The initial and long-term outcomes of the carbon ion–implanted stent were excellent. However, it did not improve long-term outcomes vs the bare metal stent.