LVI was about 7 for stented lesions versus about 6 for non-stented lesions after intervention. However, at follow-up the LVI was reduced to about 6 equal to that of the lesions that were not re-stented.

Placebo patients had a similar outcome: placing new stents or overlapping a new stent with the original stent initially demonstrated good results, but that benefit too disappeared after six months.

New cell growth was almost twice as common in re-stented segments treated with irradiation compared to those restented segments not treated with radiation.

Based on this analysis, bare stents do not achieve a good long term outcome. And regardless of supplementary radiation, repeat stenting strategies provided little long-term advantage. Radiation is best reserved for those lesions that are not restented.

Morino theorized that the same problem that causes initial stent failure causes the re-stenting procedure to fail: a heightened immune response to the presence of the metal stent triggers the vessel to begin growing new cells, a process called neointimal hyperplasia. The problem is the bare stent, not the way the stent is placed, he says.

One way to overcome this problem might be the use of drug-eluting stents, which are experimental stents that are coated with drugs that block neointimal hyperplasia.

Radiation is used to prevent neointimal proliferation in the old stent, but it may prevent the normal growth of cells needed to secure the new stent to the blood vessel, suggests Morino.

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Contact: Carole Bullock
carole.bullock@heart.org
214-706-1279
American Heart Association
13-May-2002