Background: in acute myocardial infarction (MI), decreasing compliance of the left ventricle is directly associated with prognosis. Patients and Methods: 30 patients presented with acute ST segment elevation MI Who underwent primary PCI within 12 hours of presentation. All patients were subjected to full history taking, physical examination, serial ECG, cardiac enzymes and measurement of LVEDP just before and after Primary PCI using end hole catheter. Results: post revascularization left ventricular end diastolic pressure (LVEDP) decreased. There is significant correlation between LVEDP change and left ventricular dysfunction (p value:0.014). Significant correlation between LVEDP and mortality are present. Conclusion: change in LVEDP measured just pre and post primary PCI are significantly correlated with adverse clinical outcome in patients with acute STEMI.