Intracoronary radiation for the prevention of restenosis following PTCA

The prevention and treatment of a restenosis, which occurs in ca. 30% of the cases following balloon dilatation of coronary stenoses, using intravascular radiation relies on the proliferation deterrent that is inherent in every radiation therapy. A total of 12 placebo-controlled, randomized trials have been completed: 7 regarding in-stent restenosis, 2 regarding de-novo stenosis (or restenosis without a stent) as strict inclusion criteria, and 3 with all types of stenoses. In these 12 trials, 1,676 patients were allotted to the placebo groups and 1,794 to the therapy groups. For in-stent restenoses, vessel size as defined for inclusion was between 2.4 mm und 5.5 mm, stenosis length between < 20 mm and ≤ 80 mm. In all trials with in-stent restenosis, the primary endpoints were reached; the restenosis rate in the longest coronary segment analyzed was between 45% and 68.8% in the control groups and between 21% and 53.5% in the brachytherapy groups. The respective values for the TVR were between 24.1% and 67.6% in the control groups and between 16% and 41.7% in the brachytherapy groups. In the control groups, MACE was between 25.9% and 67.6%; it was between 18% and 41.7% in the brachytherapy groups. Attaining results for de-novo stenoses was problematic due to 'geographic miss' apparently playing a larger role in these cases; but when taking this into consideration, good results were also attained. The known limitations due to late stent thromboses (4-15% in older trials) were to the most part eliminated by administration of clopidogrel for one year and the limitations due to the 'edge effect' by the application of longer radiation sources. With antiproliferative coated stents as treatment for de-novo stenoses, we can count on intracoronary brachytherapy losing significance in this area. But for in-stent restenoses, intracoronary brachytherapy is the only evidence-based interventional form of therapy. (orig.)