PURPOSE: To investigate the clinical value of two-phase ECG-gated cardiac CT in the prediction of early functional outcome in patients with chronic ischemic heart disease. MATERIALS AND METHODS: Fifty-three consecutive patients underwent preoperative two-phase ECG-gated dual source cardiac CT: first pass and 10-minute delayed phase. Preoperative and 3-month follow-up 99mTc sestamibi-gated SPECT were performed as a standard reference. Two observers evaluated the transmural extent of early hypo-enhancement (EH) and late hyper-enhancement (LH) in an 18-segment model on a 5-point scale: none (0), 1-25% (1), 26-50% (2), 51-75% (3), or >75% (4). On per patient analysis, ischemic score (the sum of transmural scores of EH minus LH in each segment) and infarct score (the sum of transmural scores of LH analyzed on segmental basis) was calculated and correlated with change of ejection fraction (EF) after revascularization. On segmental analysis, CT enhancement patterns were classified into 4 groups: no EH and no LH (A), EH and no LH (B), LH with <50% transmural extent (C), and LH with transmural extent of ���50% (D). Viable myocardium was defined as <50% transmural extent of LH. Segmental functional recovery was defined as improvement in wall motion between preoperative and follow-up SPECT. RESULTS: On per patient analysis, ischemic score showed positive correlation with improvement of EF (r=0.35, P=0.010 in all; r=0.58, P=0.023 in patients with EF���45; r=0.45, p=0.017 in patients with LH). Infarct score was inversely correlated with improvement of EF (r= -0.30, P=0.026 in all; r= -0.60, P=0.019, in patients with EF���45; r= -0.50, p=0.007 in patients with LH). On segmental analysis, from 285 dysfunctional segments, functional recovery was observed in 108 (90%) of 120 in group A, 56 (82.4%) of 68 in group B, 21 (55.3%) of 38 in group C, and 1 (1.7%) of 59 in group D (p<0.001). With a threshold of 50% transmural extent of LH, sensitivity, specificity and overall accuracy of CT for predicting function recovery was 58.6%, 99.5%, and 85.3%, respectively. CONCLUSION: Two-phase ECG-gated cardiac CT provides valuable information of regional and global functional improvement after revascularization in chronic ischemic heart disease. CLINICAL APPLICATION: Two-phase ECG-gated cardiac CT can be a valuable tool in selecting patients for revascularization by predicting regional and global early functional outcome after surgical revascularization.