Objective: Selective cyclo-oxygenase-2 (COX-2) inhibitors have been shown to preserve hemodynamic performance in experimental models of acute myocardial infarction (AMI) in rodents. The impact of COX-2 inhibition on apoptosis, vascular density, and postinfarction remodeling has not yet been fully characterized. The aim of the present study was to evaluate the effects of parecoxib, a selective COX-2 inhibitor, in an experimental AMI model in the rat. Methods: Twenty-four male Wistar rats (10 weeks of age, weighing 350-500 g) underwent surgical left coronary artery ligation. Four animals died within 24 hours. Starting on day 2, 10 rats received parecoxib (0.75 mg/kg intraperitoneal) daily for 5 days and the remaining 10 received NaCl-0.9%. Animals underwent transthoracic echocardiography before surgery and 7 days later for the measurement of end-diastolic and end-systolic diameter and wall thickness; thereafter, animals were sacrificed and histological analysis was performed to evaluate cardiomyocyte apoptosis and small arteriolar density. Data are expressed as mean and standard error. Results: Three saline-treated (30%) and zero parecoxib-treated animals died before day 7. Compared with saline-treated animals, rats treated with parecoxib had a smaller end-diastolic diameter (6.3 +/- 0.1 vs. 7.0 +/- 0.1 mm, P = 0.018) and end-systolic diameter (2.7 +/- 0.1 vs. 3.9 +/- 0.1 mm, P = 0.027), and had a greater fractional shortening (57 +/- 1 vs. 45 +/- 2%, P = 0.050). Systolic thickness in the anterior (infarct) wall was also significantly greater in the parecoxib-treated animals (3.2 +/- 0.1 vs. 2.7 +/- 0.1 mm, P = 0.008), while the posterior wall was not significantly affected (P = 0.08). Aneurysmal dilatation of the left ventricle was more frequent in saline-treated versus parecoxib-treated animals (43 vs. 0%, P = 0.025). Parecoxib treatment was associated with lower apoptotic rates (1.0 +/- 0.2 vs. 4.0 +/- 0.4%, P