Mechanisms of balloon angioplasty and repeat stenting in patients with drug-eluting in-stent restenosis.

Background: Mechanisms of lumen gain during reinterventions in patients with drug-eluting stent (DES) in-stent restenosis (ISR) remain unsettled.

Methods: We sought to assess the mechanisms of acute lumen gain after balloon angioplasty (BA) and repeat drug-eluting stent (DES) implantation in patients with DES-ISR. Following a prospective protocol 29 consecutive patients with DES-ISR were sequentially treated with BA and new DES implantation under a multimodality intracoronary imaging assessment including intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Imaging studies were systematically obtained, at baseline, after BA, and after DES. Results of interventions were compared using volumetric and morphometric (ISR pattern and injury score) analyses.

Results: IVUS and OCT demonstrated that acute lumen gain after BA and DES equally results from a reduction in intra-stent neointimal volume and further DES expansion. As compared with BA, repeat DES implantation not only increased final lumen (baseline 39.6±18.5mm(3), post-BA 58.6±26.6mm(3), post-DES 84.2±30.8mm(3), all p<0.001) but also provided a smoother lumen (injury score 1.57±0.86 vs 0.22±0.26, p<0.001). At the 9th month of angiographic follow-up (86% patients) in-stent late loss was 0.44±0.5mm and 4 patients (16%) developed ISR. The ISR pattern on OCT was not associated with the injury score after interventions or late angiographic findings. Likewise, the injury score did not predict late angiographic outcome.

Conclusions: In patients with DES ISR, lumen gain equally results from a reduction in intra-stent neointimal volume and further DES expansion. As compared with BA, repeat DES implantation provides a larger and smoother coronary lumen.