In a 66-year-old patient with prolonged episodes of chest pain, catheter angiography revealed total occlusions of the right coronary artery and the distal circumflex artery (CX) as well as 2 sequential significant stenoses in the proximal CX and one significant stenosis in the proximal left anterior descending artery (LAD). To identify the culprit lesions with their respective territory, noninvasive assessment of viability was performed by F-18 FDG positron emission tomography (PET) and fused with a low-dose computed tomography coronary angiography using prospective electrocardiogram gating. Fused PET/computed tomography coronary angiography images demonstrated a large scar in the inferior myocardium, corresponding to the total occlusion in the right coronary artery, viable myocardium in the territory of the CX, and infarcted scar tissue with partially preserved viability in the anterior myocardium, corresponding to the presumably recanalized lesion in the LAD. The patient was scheduled for revascularization of the lesions in the LAD and the CX to reverse dysfunctional but viable myocardial segments.