Background: Restenosis following percutaneous transluminal coronary angioplasty continues to be a major limitation of the procedure. To test whether an angiotensin-converting enzyme inhibitor may reduce restenosis, this study utilized an atherosclerotic, stented, Hanford miniature swine model of restenosis.
Methods: Each animal first was started on an atherogenic diet and had balloon abrasion of the left anterior descending and right coronary arteries. Four months later, balloon-mounted coil stents were placed into the abraded coronary arteries of each animal. Twenty-four animals then were randomly assigned to one of two groups: enalapril, and control. The enalapril group received 50 mg orally twice daily starting 1 week before intracoronary stenting.
Results: Follow-up 2 months later revealed angiographic stenosis in the control group of 30% +/- 13%/25% +/- 10% (left anterior descending/right coronary artery) versus 37% +/- 9%/20% +/- 11% in the enalapril group (P = not significant). The change in minimal lumen diameter from immediately after stenting to follow-up was not significantly different between control and enalapril groups. Area stenosis and maximal intimal thickness obtained by morphometric analysis were also compared, and the mean percentage area stenosis for the control group was 39 +/- 12%/31% +/- 16% and for enalapril 36% +/- 14%/35% +/- 19%. The maximal intimal thickness in the control group was 573 microns +/- 204 microns/605 microns +/- 266 microns and in the enalapril group 530 microns +/- 220 microns/424 microns +/- 237 microns. There was no statistical difference.
Conclusions: Enalapril fails to reduce restenosis in this animal model.