Background: The CFR measured after elective percutaneous coronary intervention (PCI) was predictive for recovery of LV function, however CFR measured after primary PCI within 24 hours was not in AMI. We compared the relationship between LV function and CFR measured within or after 24hours revascularization in anterior AMI patients. Methods: We studied 35 patients with primary PCI (6.2짹3.5 hours) and 48 patients with elective PCI (5.96짹3.0 days). After PCI, CFR was assessed at left anterior descending artery by intracoronary Doppler wire. All patients were performed echocardiography and assessed end-systolic volume index (ESVI), end-diastolic volume index (EDVI), ejection fraction (EF), global (G) and anterior wall motion score index (A-WMSI) on admission and follow-up (mean: 10짹8months). Results: The CFR measured after primary PCI was not correlated with change of EF, WMSI, A-WMSI but correlated with change of ESVI (r=-0.345, p=0.043) and EDVI (r=-0.373, p=0.028). However, the CFR after elective PCI was strongly correlated with the change of ESVI (r=-0.566, p<0.001), EDVI (r=-0.652, p<0.001), EF (r=0.416, p=0.003), G-WMSI (r=-0.298, p=0.04) and A-WMSI (r=-0.363, p=0.01). By using 1.4 as the cut-off value, CFR was able to predict the change of ESVI in elective PCI patients (AUC= 0.908, sensitivity 92.3%, specificity 86.4%) and primary PCI patient (AUC= 0.750, sensitivity 90.5% specificity 50.0%). Conclusion: The CFR measured after elective or primary PCI in patients with anterior wall AMI can predict LV remodeling. The CFR measured after elective PCI can predict recovery of LV function but the CFR measured after primary PCI cannot predict functional recovery.