Stent placement is now widely accepted to improve the results of angioplasty (an operation to widen the blood vessel) and decreasing the need for further surgery. Despite their worldwide acceptance, stent usage is still limited by renarrowing which occurs within the stent (restenosis) in some patients within the first six months. In addition there still exists a small risk of heart attacks soon after the stent is placed. The purpose of this study is to test the safety and tolerability of trying to place the stents using a different strategy of using low pressure oversized balloon inflations as opposed to the usual high pressure balloon inflations. This may reduce injury to the artery and reduce the chance of renarrowing of the stent. In order to ensure this is a safe and effective way of performing the procedure the investigators intend to use an Intravascular ultrasound (IVUS) catheter to look from inside the artery at the stents. IVUS has proven to be the best way of ensuring optimal stent placement. Primary hypothesis: Stents will be equally well expanded and apposed using a strategy of oversized stenting at normal inflation pressures ( \< 10 atmospheres ) as compared to high pressure inflation (≥14 atmospheres) as guided by intravascular ultrasound imaging. Secondary Hypothesis: There will be no difference in acute clinical endpoints (death, myocardial infarction, urgent revascularisation or stent thrombosis) using a strategy of oversized stenting at normal inflation pressure as compared to high pressure inflation. Tertiary Hypothesis: If the above is shown to be true the investigators would hope to expand the study in order to reveal a decrease in stent restenosis using a strategy of lower pressure balloon inflations. The investigators will assess the deployment characteristics of drug eluting versus bare metal stents
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
40
Stent can include both bare metal stents and drug eluting stents. Depending on availabilities, different stent brands may be used.
Stent can include both bare metal stents and drug eluting stents. Depending on availabilities, different stent brands may be used.
Department of Cardiology
Liverpool, New South Wales, Australia
Number of stents which are optimally deployed as assessed against the MUSIC criteria
The criteria for optimal stent expansion are: 1\. Complete apposition of the stent over its entire length against the vessel wall. 2a. In stent minimal luminal area (MLA) \>= 90% of the average reference luminal area or \>=100% of lumen area of the reference segment with the lowest lumen area. In stent lumen area of proximal stent entrance \>= 90% of proximal lumen area. 2b. Where the instent luminal area is in excess of 9.0 mm2 , the following criteria apply: In stent MLA \> 80% of the average reference lumen area or \>=90% of lumen area of the reference segment with the lowest lumen area. In stent lumen area of proximal stent entrance \>= 90% of proximal lumen area. 3. Symmetric stent expansion defined by lumen diameter (LD)min / LD max \>= 0.7 A less rigorous criteria for stent expansion will also be assessed: 1. In stent MLA \> 80% of the average reference lumen area; \& 2. Complete apposition of the stent over its entire length against the vessel wall
Time frame: Immediately after stent is deployed until optimal deployment is achieved
Clinical endpoints including death, myocardial infarction, coronary artery bypass surgery, repeat percutaneous intervention, stent thrombosis, myonecrosis
Time frame: 1-3 days following procedure and at 6 months
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