Abstract 3438: Impact of Different Pre-dilatation Strategies on Stent Expansion: An Intravascular Ultrasound Study
Background: Stent expansion remains an important predictor of both restenosis and subacute thrombosis - even in the drug-eluting stent (DES) era. The role of different pre-dilatation strategies has yet to be established in the DES population. Compliance charts were developed to guide stent size selection and predict final minimum stent diameter (MSD) and area (MSA).
Methods: We studied 224 consecutive pts with 299 de novo lesions treated with one, ≥2.5mm DES (Cypher® or Taxus®) under intravascular ultrasound (IVUS) guidance without post-dilation: (I) direct stenting without pre-dilatation (n=145); (II) conventional semi-compliant balloon (n=117) and (III) pre-dilatation with a new scoring balloon (AngioSculpt [ASC], n=37). Stent expansion was defined as the ratio of IVUS-measured MSD and MSA to the predicted stent diameter (PSD) and area (PSA).
Results: Baseline patient and lesion characteristics did not significantly differ across the groups. Only 0.6% of direct-stent pts and 5% stents placed after conventional pre-dilatation achieved PSD as opposed to 18.9% of stents pre-treated with ASC (p<0.001). The MSA/PSA and MSD/PSD ratios were larger with ASC pre-dilatation; and a greater percentage of stents had a final MSA >5.0mm2 (another commonly accepted criteria of adequate DES expansion). Lesion morphology, stent and lesion length, and reference vessel size did not affect DES expansion (Table⇓).
DES are commonly underexpanded and fail to achieve even minimum standards of stent expansion (MSA=5.0mm2).
Conventional balloon pre-dilatation does not improve the final stent expansion compared to direct stenting.
Pre-treatment with ASC enhances stent expansion and minimizes the difference between predicted and achieved stent dimensions.
Compliance charts fail to predict the MSD and MSA after DES implantation.
Pre-intervention grey-scale IVUS assessment of lesion morphology and morphometry do not predict stent underexpansion.