Objective: To determine if an aggressive approach to coronary revascularisation with oversized balloons is counterproductive, we studied the effect of increasing balloon-to-artery (B:A) ratio on neointimal hyperplasia following primary stent placement using a non-atherosclerotic porcine coronary overstretch model.
Methods: 60 vessels in 33 Yorkshire swine were randomly assigned to one of five B:A ratios between 1.0:1 and 1.4:1. Intravascular ultrasound (IVUS) imaging was performed before bare-metal stent placement to accurately determine vessel size, after stent placement, and at 28 days.
Results: The mean prestent vessel diameter was 3.05 (0.31) (SD) mm. In-stent neointimal volume, in-stent volume stenosis and cross-sectional area stenosis at the stent minimum lumen diameter increased significantly with increasing achieved B:A ratio (multilevel regression test for slope, p<0.001, p = 0.002 and p<0.001, respectively) and were independent of vessel size. Even minor vessel overstretch at an achieved B:A ratio of 1.1:1 resulted in significant neointimal hyperplasia. Larger B:A ratios were also associated with more neointima beyond the stent edges (p = 0.008). For vessels from the same animal, neointimal response at a given B:A ratio was dependent upon the animal treated.
Conclusions: In a porcine model of IVUS-guided coronary primary stent placement, vessel overexpansion is counterproductive. Neointimal hyperplasia at 28 days is strongly associated with increasing B:A ratio. In addition, vessels do not respond independently of each other when multiple stents are placed within the same animal using a range of B:A ratios.
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Competing interests: None.
Funding: This study was funded by grants from the Skaggs Clinical Scholars Program in Translational Research at The Scripps Research Institute, La Jolla, CA, USA; the Hewitt Foundation for Medical Research, Irvine, CA, USA; and The Vascular Surgery Foundation of San Diego, La Jolla, CA, USA. During the course of this work, M.Y. was an Established Investigator of the American Heart Association and a recipient of a Clinical Scientist Award in Translational Research from the Burroughs Wellcome Fund. The authors thank Boston Scientific/SCIMED for supplying coronary stents and intravascular ultrasound catheters, and Cordis Corporation for providing custom coronary guide catheters. The funding sources had no involvement in the study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
- B:A ratio
- balloon-to-artery ratio
- intravascular ultrasound