Background—Several clinical trials indicate that intracoronary radiation is safe and effective for treatment of restenotic coronary arteries. We previously reported 6-month and 3-year clinical and angiographic follow-up demonstrating significant decreases in target lesion revascularization (TLR) and angiographic restenosis after radiation of restenotic lesions. The objective of this study was to document the clinical outcome 5 years after treatment of restenotic coronary arteries with catheter-based iridium-192 (¹⁹²Ir).

Methods and Results—A double-blind, randomized trail compared ¹⁹²Ir to placebo sources in patients with restenosis after coronary angioplasty. Over a 9-month period, 55 patients were enrolled; 26 were randomized to ¹⁹²Ir and 29 to placebo. At 5-year follow-up, TLR was significantly lower in the ¹⁹²Ir group (23.1% versus 48.3%; P=0.05). There were 2 TLRs between years 3 and 5 in patients in the ¹⁹²Ir group and none in patients in the placebo group. The 5-year event-free survival rate (freedom from death, myocardial infarction, or TLR) was greater in ¹⁹²Ir-treated patients (61.5% versus 34.5%; P=0.02).

Conclusions—Despite apparent mitigation of efficacy over time, there remains a significant reduction in TLR at 5 years and an improvement in event-free survival in patients treated with intracoronary ¹⁹²Ir. The early clinical benefits after intracoronary radiation with ¹⁹²Ir seem durable at 5-year clinical follow-up.