Intravascular Ultrasound Analysis of Factors Associated with Suboptimal Stent Expansion after High Pressure Balloon Inflation

Hong, Myeong Ki; Park, Seong Wook; Lee, Cheol Whan; Lee, Sang Gon; Lee, Il Soo; Park, Hoon Ki; Kim, Jin Woo; Choi, Kee Joon; Kang, Duk Hyun; Song, Jae Kwan; Kim, Jae Joong; Kim, You Ho; Park, Jong Hoon; Park, Seung Jung

Abstract

BACKGROUND
The intracoronary stent implantation is regarded as an effective treatment modality of coronary artery disease. However, inadequate stent expansion was associated with subacute stent thrombosis and late restenosis. The high-pressure inflation stenting reduced the incidence of stent thrombosis and restenosis. Therefore, we intended to evaluate factors associated with suboptimal stent expansion after high-pressure balloon inflation.
METHODS
One hundred and thirty eight patients with 150 lesions were treated with 168 stents of various types. Intravascular ultrasound(IVUS) images were obtained after angiographic optimization(<10% or residual stenosis) with high-pressure inflation stenting. In a subgroup of 61 selected patients with 61 lesion, IVUS images were obtained before predilation of the lesions. The quantitative off-line measurement of IVUS parameters were perfoemed. An optimal stent expansion was defined by IVUS as minimal stent cross sectional area(CSA) of > or =90% of the distal reference lumen CSA. Severe calcifications were defined by IVUS as are of calcium > or =180 degree.
RESULTS
An optimal stent expansion was achieved in 67% of the 150 lesions. At preintervention, severe calcifications were in 10%(5/51) in optimal stent expansion and in 40%(4/10)in suboptimal stent expansion(p<0.05). At postintervention, minimal stent CSA was 8.0mm2 in optimal stnet expansion and 6.5mm2 in suboptimal stent expansion(p<0.01). Minor diameter at stented segment was 2.9mm in optimal stent expansion and 2.5mm in suboptimal stent expansion(p<0.01). The symmetrical index of stent expansion(SI, a ratio of the minor diameter divided by the major diameter) was 0.91 in optimal stent expansion and 0.85 in suboptimal stent expansion(p<0.01). The residual plaque burden at stented segment was larger in suboptimal stent expansion than in optimal stent expansion(56% vs 51%, p<0.01).
CONCLUSIONS
Severe calcifications at preintervention, larger residual plaque burden and smaller SI at postintervention may be related to suboptimal stent expansion, as assessed by IVUS, despite angiographic optimization with high-pressure inflation stenting.