NOVEL NANOCRYSTALLINE DIAMOND COATING OF CORONARY STENTS REDUCES NEOINTIMAL HYPERPLASIA IN PIG MODEL. RESULTS OF BIOKOM - NANOTECHNOLOGY FOR SOCIETY PROJECT

Objective: Diamond is known as hard, biocompatible material which at the same time offers possibility of functionalisation by simple covalent carbon chemistry. Our aim was to study performance of nanocrystalline diamond (NCD) coated stainless steel (SS) coronary stent in a pig coronary model. BIOKOM project is part of Nanotechnology for Society program of Academy of Sciences of Czech republic.
Methods: Specific technique (linear antenna microwave plasma enhanced CVD apparatus with a pulsed power supply) allowed coating of SS coronary stents with uniform layer of NCD with 50nm thickness. Good mechanical properties of coating were demonstrated ex vivo by micro-Raman spectroscopy, atomic force microscopy, and scanning electron microscopy previously. In January 2012 26 coronary stents (13 NCD coated and 13 SS) of 3,0/15mm size were implanted in randomized fashion into pig coronary arteries with balloon/artery ratio equal to 1.2. Follow-up angiography and optical coherence tomography (OCT) was performed at 6 weeks.  Late loss was measured in standard fashion by OCT; all stents were evaluated in 1mm cuts and statistics is based on per stent averages.  Animal experiment was approved by Czech Ministry of Health.
Results: All animals survived till follow-up and all stents were patent at angiography. There was no difference in proximal or distal reference segment size by angiography nor OCT. Average stent area of NCD/SS stent was similar at 6.36/6,23mm2, p=0.57. However there was significantly larger lumen area in NCD group – 4.8 versus 3.85mm2, p=0.02 and lumen loss was 0,39mm in NCD group versus 0,62mm in SS group, p=0.01.
Conclusion:  Implantation of nanocrystalline diamond coated coronary stent significantly reduces neointimal hyperplasia by 37% in comparison to standard stainless steel stent implantation.