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

Background and PurposeIntracoronary 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 MethodsA 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 192Ir- or a 90Sr/Y-source (prescription dose: 14–18 and 23 Gy each at 2 mm from the center of the source), or a 32P-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.ResultsClinical 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.ConclusionsRepeat 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.