Principal Findings:

Primary clinical endpoint was cumulative composite of death, MI, repeat target lesion revascularization at 6 months. At 6 months angiographic endpoints were restenosis (diameter stenosis greater than or equal to 50%), magnitude of late loss, and late loss index. Rate of restenosis (binary angiographic) was 19% in the irradiated group vs 58% in the placebo group (p=0.001). The main angiographic pattern of restenosis in the radiation group occurred at the edges of the stent. Late luminal loss was lower in the radiated vs placebo patients. Late loss index was 0.16 +/- 0.73mm in the radiated patients vs 0.70 +/- 0.46 in placebo patients (p=0.0001). At 6 months 29.2% of radiated patients had a major cardiac event (death, Q wave MI, and target vessel revascularization) vs 67.6% in the placebo group (p<0.001). There was no difference in death at 6 months between radiated (4.6%) or nonradiated groups (6.2%) and no patients had Q wave infarcts. Hence the major clinical difference was a reduction in target vessel revascularization in the radiation group (26.1%) vs the placebo group (67.6%;p<0.001). Target lesion revascularization also was lower in the radiation group (13.8%) vs the placebo group (63.1%) and the same pattern was observed at 12 months.