Neointimal coverage of stents in human coronary arteries observed by angioscopy

The aim of this study was to reveal the time course of the neointimal coverage of stents placed in the human coronary arteries.

In deciding the protocol of anticoagulant and antiplatelet therapy for patients who undergo stent implantation, the condition of the neointimal coverage of stents should be taken into consideration. However, the time course of the neointimal coverage of stents has not been elucidated in human coronary arteries.

Serial angioscopic observations were performed immediately after stenting, at 8 to 45 days (short-term follow-up) and at 65 to 142 days (long-term follow-up) in patients who underwent implantation of the Wiktor coronary stent in the restenotic lesion or in the lesion of acute or threatened closure after balloon angioplasty.

Angioscopic observations were successfully performed in 14 cases immediately after stenting, in 11 cases at short-term follow-up and in 13 cases at long-term follow-up. Immediately after stenting and even at 8 to 18 days after stenting, the stent was not covered by the neointimal layer in any case. However, at 65 to 142 days after stenting, the stent was covered by the neointimal layer in all cases. Angioscopically, three types of neointimal layer were recognized: a white layer with a cottonlike surface in three cases, a white layer with a smooth surface in eight cases and a transparent layer with a smooth surface in two cases.

Although some experimental results in animals have shown completion of neointimal coverage of stents in a few weeks, in this serial angioscopic follow-up study, the completion of neointimal coverage of stents in human coronary arteries required approximately 3 months.