Statin therapy prevents expansive remodeling in venous bypass grafts

Abstract

BackgroundVenous grafts (VG) have high failure rates by 10 years in aortocoronary bypass surgery. We have previously shown that expansive remodeling followed by increased LDL retention are early atherosclerotic changes in experimental VG placed in the arterial circulation. The objective of this study was to determine whether statin therapy prevents these expansive remodeling changes. Methods and resultsReversed jugular vein-to-common carotid artery interposition graft was constructed in 27 cholesterol-fed (0.5%) rabbits. Rabbits were randomized either to control or atorvastatin (5mg/kg/day) groups, starting two weeks prior to vein graft implantation and continuing until sacrifice at 1 or 12 weeks post-surgery. Ultrasound measurements of arterial luminal cross-sectional area (CSA) were done at day 3 and at 4, 8 and 12 weeks post-surgery. Histomorphometric measurements were performed following sacrifice at 12 weeks. Atorvastatin treatment significantly decreased total plasma cholesterol levels at 4, 8 and 12 weeks (12 weeks: 6.7±4.2mmol/L versus control 38.7±10.6mmol/L, p<0.0002). Atorvastatin significantly reduced expansive remodeling at 4, 8 and 12 weeks (lumen CSA: 44.6±6.6mm2 versus control 77.6±10.7mm2, p<0.0001). Intimal CSA by histomorphometry was also significantly reduced by atorvastatin at 12 weeks (5.59±2.19mm2 versus control 9.57±2.43mm2, p<0.01). VG macrophage infiltration, MMP-2 activity and metalloelastase activity were reduced in the atorvastatin treated group. ConclusionAtorvastatin inhibits both expansive remodeling and intimal hyperplasia in arterialized VG, likely through inhibition of macrophage infiltration and reduction of tissue proteolytic activity. The mechanism proposed above may be important for preventing VG atherosclerosis and late VG failure.