Effects of Intracoronary b-Radiation Therapy After Coronary Angioplasty An Intravascular Ultrasound Study

Background—Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound. Methods and Results —Through a 5F noncentered catheter for delivery of a Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was 20.0260.60 mm, with a 20.0960.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.6961.72 mm 2 after treatment to 6.04 62.63 mm at follow-up), with no significant change in external elastic membrane area (13.71 64 54 to 14.2264.71 mm) over the 6-month follow-up. Wall area was 8.01 63.85 mm after radiation therapy and 8.1963.44 mm at follow-up (P5NS). No significant differences were noted between the different dose groups. Conclusions—b-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, b-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up. (Circulation. 1999;99:1660-1665.)