A new platinum balloon-expandable stent (Angiostent) mounted on a high pressure balloon: acute and late results in an atherogenic swine model.

BACKGROUND

Randomized studies have proven the efficacy and safety of stent placement to treat de novo coronary stenosis. However, the poor radio-opacity and the use of an additional high-pressure balloon to fully expand the stent are the major limitations of the currently clinically-approved stents.

OBJECTIVE

We evaluated the safety, efficacy, angiographic and histologic effect of a new platinum balloon expandable stent mounted on a high-pressure balloon in Yucatan miniature swine fed high cholesterol diet.

METHODS

Fifteen Angiostents (NuMED, Inc., Hopkinton, NY and Angiodynamics, Glens Falls, NY) (coronary stent was 3, 3.5, or 4 mm in diameter and 12 mm long; renal and carotid stents were 5 mm in diameter and 13 mm long) mounted on a high-pressure balloon were placed percutaneously in blood vessels of 10 pigs [5 in circumflex (CX), 2 in left anterior descending (LAD), 5 in renal and 3 in carotid arteries]. The stent was 10-20% larger than the native vessel diameter. All animals received 5000 I.U. of heparin during the procedure and were maintained on 325 mg aspirin daily. Follow-up angiography and histology in the animals was performed at 2, 4, 12, 20, 26 and 52 weeks.

RESULTS

The stents were easily visualized with fluoroscopy and placed in all animals without episodes of balloon rupture or embolization. There was no episode of acute thrombosis. Follow-up angiography in the animals revealed patency of all renal and carotid stents, however, 2/7 coronary stents in the animals revealed angiographic lumen narrowing (> 20%) at 20 and 52 weeks. Histologic examination revealed neointimal formation at the stent site with an average neointimal thickness ranging from 325-650 microns.

CONCLUSION

This stent was safe in this animal model, easily deployed, had excellent radio-opacity and with good short-term patency without anticoagulation. Clinical trials and experience is underway.