Clinical and angiographical follow-up after implantation of a 6-12 μCi radioactive stent in patients with coronary artery disease

Aims: This study is the contribution by the Thoraxcenter, Rotterdam, to the European ³²P Dose Response Trial, a non-randomized multicentre trial to evaluate the safety and efficacy of the radioactive Isostent™ in patients with single coronary artery disease. Methods and Results: The radioactivity of the stent at implantation was 6-12 μCi. All patients received aspirin indefinitely and either ticlopidine or clopidogrel for 3 months. Quantitative coronary angiography measurements of both the stent area and the target lesion (stent area and up to 5 mm proximal and distal to the stent edges) were performed pre- and post-procedure and at the 5-month follow-up. Forty-two radioactive stents were implanted in 40 patients. Treated vessels were the left anterior descending coronary artery (n = 20), right coronary artery (n = 10) or left circumflex artery (n=10). Eight patients received additional non-radioactive stents. Lesion length measured 10 ± 3 mm with a reference diameter of 3.07 ± 0.69 mm. Minimal lumen diameter increased from 0.98 ± 0.53 mm pre-procedure to 2.29 ± 0.52 mm (target lesion) and 2.57 ± 0.44 mm (stent area) post-procedure. There was one procedural non-Q wave myocardial infarction, due to transient thrombotic closure. Thirty-six patients returned for angiographical follow-up. Two patients had a total occlusion proximal to the radioactive stent. Of the patent vessels, none had in-stent restenosis. Edge restenosis was observed in 44%, occurring predominantly at the proximal edge. Target lesion revascularization was performed in 10 patients and target vessel revascularization in one patient. No additional clinical end-points occurred during follow-up. The minimal lumen diameter at follow-up averaged 1.66 ± 0.71 mm (target lesion) and 2.12 ± 0.72 (stent area); therefore late loss was 0.63 ± 0.69 (target lesion) and 0.46 ± 0.76 (stent area), resulting in a late loss index of 0.65 ± 1.15 (target lesion) and 0.30 ± 0.53 (stent area). Conclusion: These results indicate that the use of radioactive stents is safe and feasible, however, the high incidence of edge restenosis makes this technique currently clinically non-applicable.