RISK-FACTORS FOR ACUTE AND SUBACUTE STENT THROMBOSIS AFTER HIGH-PRESSURE STENT IMPLANTATION - A STUDY BY INTRACORONARY ULTRASOUND

Background In the era of coronary stenting with high-pressure expansio n, stent thrombosis remains a major life-threatening risk. Because of its superior imaging mode, intracoronary ultrasound could provide insi ght into potential risk factors for stent thrombosis. Patients and Met hods In 215 patients with stent implantations controlled by intracoron ary ultrasound, four occurrences of subacute stent thrombosis, two com plete acute thrombotic occlusions, and four occurrences of incomplete acute thrombosis were observed. All scents were expanded with inflatio n pressures of at least 14 atm (17 +/- 3 atm). The clinical data and t he qualitative and quantitative ultrasound information were compared b etween stents with thrombosis and stents without thrombosis. The lumin al area and the plaque harder of the reference segments, and of the sm allest and largest site of the stented segment after the initial and f inal expansion, were measured. Results Stents in the left anterior des cending artery were more often involved in stent thrombosis than other vessels, but the vessel dimensions in this target vessel were smaller than in the right coronary artery. The plaque burden was considerably larger after stent implantation with subsequent thrombosis compared w ith no thrombosis (74.1 +/- 8.8% vs 63.6 +/- 8.0%; p < 0.001), and the stent area was smaller (4.80% +/- 1.33 mm(2) vs 6.86 +/- 2.08 mm(2); P < 0.01). In stents with thrombosis the plaque burden of the stent si te with the smallest and largest lumen differed by 15.2%, whereas the difference in plaque burden in stents without thrombosis was 2.7%. Int racoronary ultrasound showed that the best risk predictor of thrombosi s was the residual plaque burden of the stented segment (odds ratio 15 .7 [confidence interval 2.4 to 104.7]), and a small stent area after i mplantation (odds ratio 6.8 [confidence interval 1.9 to 24.3]). Conclu sion in a multivariate risk analysis plaque burden was the strongest i ndependent risk factor for stent thrombosis. The amount of residual pl aque mass around the stent might be a potential trigger for thrombus f ormation.