Serial intravascular ultrasound of intracoronary gamma-radiation assessment of the efficacy therapy for preventing recurrence in very long, diffuse, in-stent restenosis lesions

Background-The efficacy of coronary gamma -irradiation in preventing recurr ent in-stent restenosis (ISR) is well established. However, brachytherapy m ay be less effective in very long, diffuse ISR lesions. Methods and Results-We used serial intravascular ultrasound (IVUS) to study patients with long, diffuse ISR lesions (length, 36 to 80 mm.) who were en rolled in (1) Long WRIST (Washington Radiation In-Stent Restenosis Trial), a double-blind, placebo-controlled trial of intracoronary gamma -irradiatio n (15 Gy at 2 mm from the source) and (2) high-dose (HD) Long WRIST, a regi stry that used a dose prescription of 18 Gy at 2 mm from the source. IVUS w as performed using automated pullback (0.5 mm/s). Stent, lumen, and intimal hyperplasia were measured at 2-mm intervals. Complete postintervention and follow-up IVUS imaging was available in 30 irradiated and 34 placebo patie nts from Long WRIST and in 25 patients from HD Long WRIST. Stent length was longer in HD Long WRIST than in placebo or treated patients in Long WRIST (P = 0.0064 and P = 0.0125 respectively). Otherwise, baseline measurements were similar. At follow-up, the minimum lumen area was largest in the HD Lo ng WRIST patients (4.0 +/- 1.4 mm); areas were 2.9 +/- 1.0 mm(2) in irradia ted patients in Long WRIST and 1.9 +/- 1.1 mm(2) in placebo patients in Lon g WRIST (P < 0.005 for all comparisons). Conclusions-Serial IVUS analysis shows that gamma -irradiation reduces recu rrent in-stent neointimal hyperplasia in long, diffuse ISR lesions; however , it is even more effective when given at a higher dose.