Post acute myocardial infarction (AMI) left ventricular (LV) remodeling begins within hours of the acute event with permanent consequences. Previous studies have demonstrated that LV remodeling is one of the major determinants of long-term survival post AMI. Recent studies have reported that the cardiac natriuretic peptides, atrial natriuretic peptide (ANP) and BNP have direct anti-fibrotic and anti-proliferative effects on the myocardium. More importantly, it has been reported that in the acute phase of AMI, the secretion of the cardiac natriuretic peptides may be insufficient relative to the chronic phase. Therefore, augmentation of the cardiac natriuretic peptide system, such as by exogenous administration of exogenous peptide may prevent post AMI LV remodeling because of the cardioprotective effects. The objective of this study is to to determine the efficacy of IV human BNP (Nesiritide) as compared to placebo to prevent adverse post AMI LV remodeling. This is a randomized double blinded placebo controlled study to determine efficacy of 72 hours of IV BNP at 0.006µg/Kg/min as compared to placebo in patients with anterior ST-elevation myocardial infarction and successful revascularization. The study population will include 60 patients admitted to the Cardiac Care Unit with a first anterior AMI and successful reperfusion therapy (TIMI grade 3 flow) within 24 hours of onset of chest pain documented by coronary angiography.