Hypercholesterolemia and chronic ischemia alter myocardial responses to selective cyclooxygenase-2 inhibition.

OBJECTIVE

Cyclooxygenase-2 inhibitors have been implicated in adverse cardiac events. We hypothesize that hypercholesterolemia and ischemia may alter the myocardial response to the cyclooxygenase-2 inhibitor celecoxib.

METHODS

Yorkshire swine fed normal chow (CX, n = 6) or high-cholesterol diet (HCX, n = 6) underwent placement of an Ameroid constrictor on the left circumflex artery and were started on celecoxib (200 mg/day). After 7 weeks, ischemic and nonischemic myocardium was analyzed for thrombogenic ratio (thromboxane content divided by prostacyclin content), total protein oxidative stress, and expression of prostacyclin synthase, thromboxane synthase, myeloperoxidase, and superoxide dismutase. Cardiac function, tissue perfusion, and vessel density were measured.

RESULTS

HCX animals were significantly hypercholesterolemic compared with CX animals. Thrombogenic ratio was significantly higher in the HCX group than in the CX group, but prostacyclin and thromboxane synthase expression was similar in all tissues. Myocardial perfusion was decreased in the HCX group compared with the CX group. Total oxidative stress, myeloperoxidase, and superoxide dismutase were increased in ischemic tissue compared with nonischemic tissues, but there was no diet-induced difference between groups. There was no difference in capillary or arteriolar density between groups. Left ventricular contractility was greater in the HCX group than in the CX group, but there was no significant difference in heart rate, mean arterial pressure, or left ventricular pressure.

CONCLUSIONS

Hypercholesterolemic patients using celecoxib may be at higher risk for thrombotic events than those with normal cholesterol, but the relationship between dyslipidemia, ischemia, and cyclooxygenase-2 inhibition is likely much more complicated than originally thought.