Stent healing response following delivery of paclitaxel via durable polymeric matrix versus iopromide-based balloon coating in the familial hypercholesterolaemic swine model of coronary injury

Aims: The routine use of paclitaxel-coated balloons (PCB) in combination with bare metal stents (BMS) in de novo coronary lesions has been questioned. In this study, we aimed to compare the vascular response of BMS implanted using a second-generation PCB (BMS+PCB) with the TAXUS stent (PES) and a BMS control (BMS) in the familial hypercholesterolaemic swine (FHS) model of coronary injury. Methods and results: A total of 17 stents (PES=6, BMS+PCB=6, and BMS=5) were implanted in the coronary territory of 10 FHS using a 20% overstretch injury ratio. Imaging evaluation (QCA and IVUS) was conducted in all animals at baseline and 28 days following stent implantation. Following terminal imaging all animals were euthanised and stented coronary segments harvested for histological evaluation. At 28 days, the lowest degree of percentage diameter stenosis by QCA was achieved by the PES (2.9±9%) followed by the BMS+PCB (9.5±16.4%) and the BMS group (25.65±18.7%, p<0.05). In histology, percentage area of stenosis (BMS+PCB=29.6±6.4% vs. PES=21.5±3.3% vs. BMS=55.2±12.9%; p<0.01) and neointimal thickness (BMS+PCB=0.26±0.1 mm vs. PES=0.21±0.1 mm vs. BMS=0.59±0.2 mm; p<0.01) were significantly reduced in both paclitaxel groups in comparison to BMS controls. Both BMS+PCB and BMS groups had higher endothelialisation scores (PES=1.50±0.9 vs. BMS+PCB=2.73±0.4 vs. BMS=3.00; p<0.05) and lower peri-strut inflammatory scores (PES=0.83±0.4 vs. BMS+PCB=0.20±0.2 vs. BMS=0.43±0.6, p<0.05) when compared to PES. Neointima maturity (PCB+BMS: 2.00 [2-2.4] vs. PES: 1.00 [0.3-1] vs. BMS: 3.00, p<0.05) and fibrin deposition (PCB+BMS: 1.40±0.3 vs. PES: 2.17±0.7 vs. BMS: 0.27±0.3, p<0.05) scores in PCB+BMS appeared to fall between the PES and the BMS ranges.