Background: In severe coronary artery disease (CAD) it has been shown that intramyocardial inotropic reserve, as assessed with tagged magnetic resonance imaging (MRI), is uniformly distributed among positron emission tomography (PET)-patterns reflecting normal or concomitant reductions in perfusion and glucose metabolism. This preliminary study aimed to delineate the relationship between preoperative values of intramyocardial inotropic reserve (in different PET-patterns of perfusion and glucose uptake) and intramyocardial functional outcome after surgical revascularization in severe CAD. Methods and Results: Twelve patients underwent preoperative tagged MRI (baseline/10 µg.kg^-1.min^-1 of dobutamine), H₂ ¹⁵O/¹⁸FDG-PET imaging, and postoperative resting tagged MRI. Regional midmyocardial circumferential shortening (Ecc; %) and PET-patterns (normal, match-viable, mismatchviable, and infarcted) were assessed in 3 tagged MRI/PET short-axis slices. Ecc at baseline ranged from 12±6% to 8±5% and 4±4% in normal, match-viable and infarcted regions respectively (p<0.05), and was 8±5% in mismatch-viable regions. 187 of the 429 studied regions showed Preoperative inotropic reserve under dobutamine, but 238 showed postoperative functional improvement. Postoperative functional improvement was less common in infarcted regions (41%, vs ~60% in the other PET-patterns), but the extent of improvement was similar among PET-patterns (~6%). Postoperative functional improvement occurred in 53% of all (normal, match-viable, and mismatch viable) regions without inotropic reserve. Conclusions: In severe CAD, revascularization affords greater intramyocardial functional benefit than expected from the evaluation of intramyocardial inotropic reserve with low-dose dobutamine. Postoperative functional improvement in PET-viable regions without inotropic reserve suggests that factors other than regionally enhanced perfusion contribute to such functional improvement.