Intravascular ultrasound assessed incomplete stent apposition and stent fracture in stent thrombosis after bare metal versus drug-eluting stent treatment the Nordic Intravascular Ultrasound Study (NIVUS)

BACKGROUND: This prospective multicenter registry used intravascular ultrasound (IVUS) in patients with definite stent thrombosis (ST) to compare rates of incomplete stent apposition (ISA), stent fracture and stent expansion in patients treated with drug-eluting (DES) versus bare metal (BMS) stents. ST is a rare, but potential life threatening event after coronary stent implantation. The etiology seems to be multifactorial. METHODS: 124 patients with definite ST were assessed by IVUS during the acute ST event. The study was conducted in 15 high-volume percutaneous coronary intervention -centers in the Nordic-Baltic countries. RESULTS: In early or late ST there were no differences in ISA between DES and BMS. In very late ST, ISA was a more frequent finding in DES than in BMS (52% vs.16%; p=0.005) and the maximum ISA area was larger in DES compared to BMS (1.1±2.3mm(2) vs. 0.1±0.5mm(2); p=0.004). Further, ISA was more prevalent in sirolimus-eluting than in paclitaxel-eluting stents (58% vs. 37%; p=0.02). Stent fractures were found both in DES (16%) and BMS (24%); p=0.28, and not related to time of stent thrombosis occurrence. For stents with nominal diameters ≥2.75mm, 38% of the DES and 22% of the BMS had a minimum stent area of less than 5mm(2); p=0.14. CONCLUSIONS: Very late stent thrombosis was more prevalent and associated with more extensive ISA in DES than in BMS treated patients. Stent fracture was a common finding in ST after DES and BMS implantation.