OBJECTIVE

Hypercholesterolemia contributes to coronary artery disease progression but little is known about its effect on left ventricular (LV) function after myocardial infarction (MI). The aim of this study was to investigate the effects of hypercholesterolemia and statin treatment in rabbits with experimental MI.

RESULTS

New Zealand White rabbits on a normal or cholesterol-rich diet for 4 weeks, underwent permanent coronary artery ligation. Starting on the first day post-MI rabbits were treated with either placebo or simvastatin (5 mg/kg/day) for 9 weeks. Hypercholesterolemia itself did not affect LV function in sham-operated animals but further impaired LV systolic (dP/dtmax -42%) and diastolic (dP/dtmin -47%) function in MI rabbits on placebo. Simvastatin treatment not only prevented deterioration of LV function associated with hypercholesterolemia but improved LV function (dP/dtmax +130%; dP/dtmin +144%, P < 0.05). Simvastatin also attenuated the depression of LV function in normocholesterolemic MI rabbits (dP/dtmax +46%; dP/dtmin +53%, P < 0.05). Hypercholesterolemia in MI rabbits coincided with a significant increase in C-reactive protein levels (marker of inflammation) and Rac1-GTPase activity (marker of oxidative stress), and a reduction in cardiac sarcoplasmic-reticulum calcium ATPase-2 expression and endothelial nitric oxide synthase protein phosphorylation, all of which were normalised by simvastatin treatment. Elevated serum cholesterol levels were only partially reduced by simvastatin.

CONCLUSIONS

Hypercholesterolemia further impaired the depressed LV function in rabbits post-MI. Statin treatment reversed this effect, and conferred additional protection, as in normocholesterolemic animals. Our study suggests that anti-inflammatory and anti-oxidative effects of simvastatin substantially contribute to its beneficial effects on cardiac function after MI.