Gamma radiation for in‐stent restenosis: effect of lesion length on angiographic and clinical outcomes

The relation between lesion length and effectiveness of gamma radiation treatment (gamma-RT) has not been well described. We evaluated the acute and long-term outcome according to baseline lesion length in 130 patients treated with (192)Ir in the Washington Radiation for In-Stent Restenosis Trial; 44 (35.5%) had baseline short in-stent restenosis (ISR) lesions (length < 15 mm) and 80 (64.5%) long ISR lesions (length > or = 15 mm). At 6-month follow-up after gamma-RT, the short ISR group had larger lumen dimensions and lower late loss than the long ISR group. Restenosis rate was significantly higher in patients with long ISR for both the placebo (74% vs. 39%; P = 0.01) and the gamma-RT arm (31% vs. 5.3%; P = 0.04). gamma-RT significantly improved the angiographic outcome in the short-lesion groups but had the more pronounced effect on the reduction of clinical events after treatment of long ISR group. Lesion length remains a powerful predictor of recurrent ISR and clinical events after treatment of ISR even with gamma-RT.