Abstract 4368: Impact of Baseline Thrombus on Acute Tissue Protrusion and Late Neointimal Formation After Stent Implantation in Acute Myocardial Infarction: An Intravascular Ultrasound Substudy From the HORIZONS-AMI Trial
Backgrounds: Intracoronary thrombus is a key factor in the pathogenesis of acute myocardial infarction (AMI). We assessed the relationship between pre-intervention intracoronary thrombus and tissue protrusion after stent implantation.
Methods: HORIZONS-AMI was a prospective, dual-arm, factorial, trial in which pts with STEMI were randomized to
unfractionated heparin + GPIIb/IIIa inhibition vs bivalirudin (1:1); and
paclitaxel-eluting TAXUS stents (PES) vs bare metal EXPRESS stents (BMS) (3:1).
A total of 347 pts in whom IVUS was performed after stent implantation and at 13-month follow-up were enrolled in a formal IVUS substudy and analyzed at an independent core laboratry.
Results: Intracoronary thrombus - defined as haziness, filling defect, or total occlusion on the pre-intervention angiogram - was identified in 268 (75%) pts by core laboratory analysis. Baseline clinical characteristics and stent profiles were similar between thrombus and non-thrombus groups. Direct stenting was less common in thrombus group. The incidence and volume of tissue protrusion was significantly greater in the thrombus group compared to the non-thrombus group. By multivariable logistic regression that intracoronary thrombus was an independent predictor for tissue protrusion (OR=2.2, 95%CI=1.2– 4.2, p=0.014). However, tissue protrusion volume was not correlated with neointimal hyperplasia volume at 13 month follow-up for either PES (p=0.9) or BMS (p=0.1). Similarly, the presence of angiographic thrombus at baseline was not predictive of neointimal hyperplasia (15.6 [5.2, 33.5 vs.16.1 [6.2, 33.4], p=0.96).
Conclusions: The presence of angiographic thrombus pre-intervention is an important predictor of tissue protrusion after stent implantation in pts with AMI; however, neither angiographic thrombus nor tissue protrusion is associated with neointimal hyperplasia at 13-month follow-up.