IVUS-based dosimetry on patients with repeat-radiated coronary arteries to the same site.

Abstract Background and Purpose Intracoronary radiation reduces recurrent in-stent restenosis (ISR). Repeat radiation may become necessary due to recurrent ISR. This study reports outcome-related dose calculations for twice-radiated coronary artery segments. Materials and Methods A total of 22 patients with angiographic evidence of ISR in a previously treated native coronary artery were assigned for repeat percutaneous coronary intervention and intravascular brachytherapy (IVBT). Intravascular brachytherapy was performed either with a 192 Ir- or a 90 Sr/Y-source (prescription dose: 14–18 and 23 Gy each at 2 mm from the center of the source), or a 32 P-source (20 Gy 1-mm deep to the vessel wall). The mean time interval between the two IVBT treatments was 394±306 days. For each patient, angiograms and intravascular ultrasound cross sections were reviewed, on the basis of anatomical landmarks, matched, and the twice-radiated vessel segment identified. Results Clinical follow-up at 379±146 days revealed a target vessel revascularization rate of 18.2% and a target lesion revascularization rate of 13.6%. One death was reported. Maximal dose and average dose at the endothelium were 261 and 124±72.3 Gy, and maximal dose and average dose at the adventitia–media border were 159 and 50.3±29.3 Gy. Fourteen patients had 1.71 times longer recurrence-free interval compared to the interval between both IVBT treatments. Conclusions Repeat IVBT to the same ISR site is safe without any adverse clinical events at an average 12 months' follow-up. A second IVBT treatment led to a prolonged ISR-free survival for the majority of patients. The choice of isotope did not influence outcome.