Additional stenting promotes intimal proliferation and compromises the results of intravascular radiation therapy: an intravascular ultrasound study

Background

Vascular brachytherapy (VBT) reduces in-stent restenosis (ISR). However, additional stenting at the time of radiation may be associated with a worse outcome.

Methods and results

Intravascular ultrasound (IVUS) was performed after VBT and at 6 months follow-up in 79 native artery ISR patients treated with γ-radiation who participated in the Washington Radiation for In-Stent restenosis Trial (WRIST), Gamma-1, and Angiorad Radiation Technology for In-Stent restenosis Trial in Coronaries (ARTISTIC) trials. Patients were treated with ¹⁹²Ir at 14 or 15 Gy at 2 mm from the source. Additional stents were used to treat the ISR lesions in 45 patients; these patients were then compared with the 34 patients treated without restenting. Paired measurements included stent, lumen, and intimal hyperplasia volumes. After the VBT procedure, intimal hyperplasia volume was smaller in the group treated with additional stents (54 ± 33 mm³ vs 34 ± 33 mm³, P = .012), but minimal lumen area was similar between the 2 groups (4.3 ± 1.5 mm² vs 4.7 ± 1.4 mm² respectively, P = NS). Between the time of the VBT procedure and follow-up, intimal hyperplasia volume increased by 27 ± 19 mm³ in the restented group and by 9 ± 21 mm³ in the group treated without additional stents (P = .014). At 6 months, intimal volume was similar in the 2 groups, but minimal lumen area was slightly smaller in the group treated with additional stents (3.4 ± 1.8 mm² vs 4.2 ± 1.7 mm², P = .053). Patients treated with additional stents had more target lesion revascularizations than the group treated without additional stents (38% vs 15%, P = .02).

Conclusions

Additional stenting reduces intimal hyperplasia within the stents acutely. However, it compromises the benefit of VBT by promoting higher intimal regrowth within months after radiation.