Volume 12, Number 2, March-April 2005

Immediate stent recoil: a forgotten phenomenon
Julian Gunn, David Beacock, Allison Morton, John Bowles, David Crossman

We sought to measure immediate stent recoil (before vs. after deflation of the deployment balloon) in diseased coronary artery segments. Immediate recoil has not been assessed since the early days of stenting.
We performed a prospective study in 120 consecutive, high pressure-stented coronary artery lesions. Angiographic images of the stent on the balloon during final balloon inflation, and of the reated segment of artery immediately afterwards, were recorded in two projections. The unconstrained balloon was measured at nominal pressure in the aorta for validation. Measurements were made blind, off-line. Comparison was made with the diameters quoted by the manufacturer for the balloon pressures used.
The stent deployment pressure was 12.82(SEM 0.30) atm. Measurement of the balloon at nominal pressure in the aorta disclosed an accuracy of 99% (the manufacturer's stated balloon/stent diameter at nominal pressure was 3.16[0.07] mm and the measured value was 3.20[0.07] mm). The manufacturer's stated balloon/stent diameter at deployment pressure was 3.37(0.05) mm ('100%'), whereas the balloon/stent in the diseased segment measured 3.23(0.05) mm (96[1.5]%) and the final stented segment measured 3.02(0.05) mm (90[1.5]%) (p<0.0001 for all).
Even using contemporary stents at high pressure, undersizing of the stent occurs by 4% compared to the manufacturer's stated size at deployment pressure. There is immediate recoil of a further 6% when the balloon is deflated, presumably due to constraint by the surrounding atherosclerotic vessel. Stents may prevent late, but not immediate, recoil. The stented segment diameter is 10% smaller than intended.

Br J Cardiol 2005;12:AIC15-19.

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