Therapeutic implications of in-stent restenosis located at the stent edge. Insights from the Restenosis Intra-stent Balloon angioplasty versus elective Stenting (RIBS) randomized trial

In patients with in-stent restenosis (ISR) several anatomic subgroups have been identified. ISR affecting the stent edge (EDG) is a poorly characterised subgroup with undefined therapeutic implications. We sought to determine the implications of ISR affecting the stent EDG. 450 patients included in the "Restenosis Intra-stent: Balloon angioplasty vs elective Stenting" (RIBS) randomized study, were analysed. EDG ISR was predefined in the protocol and the pattern of ISR analysed in a centralized core-lab. Fifty-two patients (12%) had EDG ISR (29 stent group, 23 balloon arm). Patients with EDG ISR had less severe [minimal lumen diameter (MLD) (0.78+/-0.3 vs 0.66+/-0.3 mm, p=0.05)] and shorter lesions (lesion length 10.2+/-6 vs 13.2+/-7 mm, p=0.003). Patients with EDG ISR more frequently required crossover (12% vs 3%, p=0.006) but eventually the immediate angiographic result and the long-term clinical and angiographic outcome was similar to that found in patients without EDG ISR. Patients with EDG ISR treated in the balloon and stent arms had similar baseline characteristics. However, after intervention, the immediate angiographic result was better in the stent arm (MLD 2.79+/-0.4 vs 2.35+/-0.3 mm, p=0.001). This difference persisted at late follow-up: MLD (1.93+/-0.7 vs 1.39+/-0.7 mm, p=0.01), recurrent restenosis (20% vs 50%, p=0.03). In addition, the 1-year event-free survival was significantly better (83% vs 52%, log rank p=0.01; Cox HR 0.28, 95%CI 0.09-0.79) in the stent arm. Moreover, stent implantation was an independent predictor of freedom from target vessel revascularization (HR 0.15, 95%CI 0.03-0.67, p=0.003). EDG ISR constitutes a specific subgroup with relevant therapeutic implications. In patients with EDG ISR, repeat stent implantation provides better clinical and angiographic outcome than conventional balloon angioplasty.