Rapid Inflation/Deflation Compared With Prolonged High-Pressure Balloon Inflation

It is universally accepted that high-pressure balloon inflation is required to most effectively deploy a coronary balloon-expandable stent. However, there is not consensus nor are there any guidelines regarding the method of balloon inflation, particularly the duration of inflation. Underexpansion and strut malapposition after stent deployment are among the most powerful predictors for adverse vessel outcomes. High-pressure inflation for stent deployment is effective to optimally expand the stent, but unlike in vitro testing in air, there are poorly distensible plaque elements that may not instantaneously yield to the balloon pressure. However, these elements may ultimately yield to prolonged inflation. Most clinical interventional cardiologists inflate for a relatively short period (15-30 sec). The investigators have noted that when balloon pressure is maintained at a certain pressure level it tends to decrease over time, and may require 60-180 or more seconds to maintain pressure stability. This finding implies that plaque elements are yielding slowly over time to the increased pressure, thus increasing expansion, and suggests that a prolonged inflation until balloon pressure stabilizes is more effective than a rapid inflation/deflation sequence to fully expand and appose the stent to the vessel wall. At present there is no consensus on stent deployment strategy. It is our hypothesis that prolonged inflation is superior to the more commonly used strategy of rapid inflation/deflation. Optimal coherence tomography (OCT), a novel technology that measures near-infrared light reflections and translates them into a 2D image, has an axial resolution nearly 10-times that of intravascular ultrasound (IVUS). Thus it is possible to examine the extent of stent malposition and stent expansion using this modality. The current randomized trial tests the hypothesis that prolonged balloon inflation until a stable balloon pressure is maintained is more effective than a rapid inflation/deflation sequence when performed to the same balloon inflation pressure.