Time Course of Stent Endothelialization After Intravascular Radiation Therapy in Rabbit Iliac Arteries

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Abstract
Background— Late total occlusion after vascular brachytherapy (VBT) continues to be a serious complication. Delayed reendothelialization was suggested as a pivotal cause, but the time course for complete healing is unknown. Methods and Results— Seventy-two rabbit iliac arteries underwent stent implantation and were treated with γ-radiation using 192 Ir. The prescribed doses were 0 Gy (controls, n=24 arteries), 15 Gy (n=24), or 30 Gy (n=24) at 2 mm. Animals were killed at 1 month (n=24), 3 months (n=24), or 6 months (n=24) and were analyzed for histomorphometry or scanning electron microscopy. Intimal area was reduced after VBT at 3 months with 15 and 30 Gy (0.66±0.07 and 0.66±0.04 mm 2 , respectively) compared with controls (1.01±0.11 mm 2 , P 2 in controls, P Conclusions— Reendothelialization after VBT is not completed at 6 months after VBT. Special care with prolonged antiplatelet therapy should be considered beyond that time point.