EFFECTS OF STENT DESIGN AND SERUM-CHOLESTEROL LEVEL ON THE RESTENOSISRATE IN ATHEROSCLEROTIC RABBITS

We investigated the effect of serum cholesterol level and stent design on the restenosis rate within the stent after balloon angioplasty and stent implantation using atherosclerotic rabbits. Two types of nickel /titanium stents with gaps (open stent) and without gaps (closed stent ) between the wire coils were implanted into the aorta of the rabbits 10 weeks after atherosclerosis had been induced using a standard high cholesterol diet and balloon abrasion. Each rabbit had an open stent a nd a closed stent implanted into the infrarenal abdominal aorta. Betwe en these two stents a control segment of the aorta was treated with an gioplasty alone. The animals were divided into two groups according to the diet protocol as follows: in group I (n = 9) a high cholesterol d iet was stopped after stent implantation; in group II (n = 10) a high cholesterol diet was maintained after stent implantation. Digital subt raction angiograms were obtained every 4 weeks for up to 24 weeks and the narrowest diameter of the arterial segments within each stent and in the segment between stents was measured. The diameter narrowing wit hin the closed stent was greater in the high cholesterol group compare d with the low cholesterol group: 12 weeks (2.57 +/- 0.09 mm in group I vs 2.14 +/- 0.15 mm in group II, mean +/- S.E., p < 0.05); 16 weeks (2.55 +/- 0.09 mm vs 2.14 +/- 0.12 mm, p < 0.05); 20 weeks (2.59 +/- 0 .06 mm vs 1.98 +/- 0.12 mm, p < 0.01); and 24 weeks (2.45 +/- 0.11 mm vs 2.01 +/- 0.11 mm, p < 0.05). No significant differences in the narr owest diameter of the arterial segments were observed between high and low cholesterol groups in the angioplasty alone areas or within the o pen stents. There was a significant difference in the narrowest diamet er between stents with versus those without gaps (at 12, 16, and 20 we eks poststenting in group I and at 4, 8, 12, 16, 20, and 24 weeks in g roup II). Thus the stent with the least metal is correlated with less stenosis and intimal hyperplasia. From these data we conclude that bot h stent deign and serum cholesterol are important factors for restenos is after stent implantation.