Preclinical randomised safety, efficacy and physiologic study of the silicon dioxide inert-coated Axetis and bare metal stent: short-, mid- and long-term outcome.

AIMS: To evaluate the short-, mid- and long-term safety, efficacy and vascular physiology of Axetis silicon dioxide (SiO2, abrading the micropores) inert-coated stent implantation in a randomised preclinical setting. METHODS AND RESULTS: Coronary arteries of domestic pigs were randomised to receive either Axetis or BMS (same design) stents with one-, three- and six-month follow-up (FUP), controlled by coronary angiography, optical coherence tomography (OCT), intravascular ultrasound (IVUS) and histology (n=32). The time-dependent vasomotor reaction of coronary arteries to stenting was measured using modified myography (n=12). Complete endothelialisation of the Axetis stent was confirmed by OCT, IVUS and histology at one-month FUP. Histopathology revealed continuous healing of the vessel wall with a gradual reduction of inflammation and fibrin score during the six-month FUP in both stent types. Significantly smaller neointimal area and %area stenosis were measured in Axetis stents compared with BMS at each FUP time point. Vascular reactivity measurements showed significantly better endothelium-dependent vasodilation of stented arteries with Axetis implantation. CONCLUSIONS: Implantation of the Axetis SiO2-coated stent resulted in a significantly better safety, efficacy and vessel physiology profile compared with BMS of the same design with a continuous decrease in vessel inflammation during the six-month FUP.

Time course of endothelium-dependent and -independent coronary vasomotor response to coronary balloons and stents. Comparison of plain and drug-eluting balloons and stents.

OBJECTIVES: This study sought to determine the time dependency of the endothelium-dependent and -independent vascular responses after percutaneous coronary intervention (PCI) with drug-eluting (DEB) or plain balloons, bare-metal (BMS), and drug-eluting (DES) stents, or controls. BACKGROUND: Long-term endothelial dysfunction after DES implantation is associated with delayed healing and late thrombosis. METHODS: Domestic pigs underwent PCI using DEB or plain balloon, BMS, or DES. The dilated and stented segments, and the proximal reference segments of stents and control arteries were explanted at 5-h, 24-h, 1-week, and 1-month follow-up (FUP). Endothelin-induced vasoconstriction and endothelium-dependent and -independent vasodilation of the arterial segments were determined in vitro and were related to histological results. RESULTS: DES- and BMS-treated arteries showed proneness to vasoconstriction 5 h post-PCI. The endothelium-dependent vasodilation was profoundly (p < 0.05) impaired early after PCI (9.8 ± 3.7%, 13.4 ± 9.2%, 5.7 ± 5.3%, and 7.6 ± 4.7% using plain balloon, DEB, BMS, and DES, respectively), as compared with controls (49.6 ± 9.5%), with slow recovery. In contrast to DES, the endothelium-related vasodilation of vessels treated with plain balloon, DEB, and BMS was increased at 1 month, suggesting enhanced endogenous nitric oxide production of the neointima. The endothelium-independent (vascular smooth muscle-related) vasodilation decreased significantly at 1 day, with slow normalization during FUP. All PCI-treated vessels exhibited imbalance between vasoconstriction-vasodilation, which was more pronounced in DES- and BMS-treated vessels. No correlation between histological parameters and vasomotor function was found, indicating complex interactions between the healing neoendothelium and smooth muscle post-PCI. CONCLUSIONS: Coronary arteries treated with plain balloon, DEB, BMS, and DES showed time-dependent loss of endothelial-dependent and -independent vasomotor function, with imbalanced contraction/dilation capacity.