Edge stenosis after intracoronary radiotherapy: angiographic, intravascular, and histological findings.

A73-year-old hypertensive, dyslipidemic man with known complex coronary artery disease has had operative revascularization twice in the last 10 years. He has also undergone multiple angioplasty procedures on the saphenous vein graft (SVG) to the obtuse marginal (OM) and right coronary arteries. The left internal mammary artery conduit to the left anterior descending artery remains patent. The SVG to the OM was treated for in-stent restenosis with Excimer laser angioplasty, and the patient was included in the SVG Washington Radiation for In-Stent restenosis Trial (WRIST) protocol. No additional stent was placed. After the intervention, the patient received intracoronary g-radiation therapy (iridium-192 ribbon39 seeds; 35 mm; Best Medical International). The prescribed dose was 15 Gy to a distance 2.0 mm from the surface of the source. The patient received Plavix (clopidogrel 250 mg BID) for 1 month and is now taking aspirin (325 mg) every day. He did well until recently, when he presented with exertional chest discomfort. Thallium stress testing demonstrated lateral wall ischemia. An angiogram taken 6 months after g-radiation showed focal edge stenosis at the proximal margin of the stent in the SVG to OM (Figure 1). Intravascular ultrasound pullback at 0.5 mm/s (3.2 F, 30 MHz, Boston Scientific/CVIS) showed a soft concentric plaque (Figure 2), which was subjected to directional atherectomy (DVI Inc) and balloon angioplasty. Two pieces of the edge restenotic tissue were analyzed histologically; they showed typical hypocellularity or acellularity after brachytherapy (Figure 3).