Prediction of reversible ischemia after coronary artery bypass grafting by positron emission tomography

Metabolic imaging using positron emission tomography (PET) facilitates the identification of ischemic but viable myocardium. In this study, the predictive value of PET for identifying improvement in regional function after coronary artery bypass grafting (CABG) was assessed. PET perfusion and metabolic imagings using N-13 ammonia and F-18 deoxyglucose (FDG) were performed before and 5-7 weeks after CABG in 25 patients with coronary artery disease. Each of the 5 myocardial segments of the left ventricle was categorized as normal, ischemic and infarcted based on the findings of perfusion and PET metabolic images. Among 58 hypoperfused segments, abnormal perfusion in 17 of 25 ischemic segments was correctly predicted to be reversible (68% prediction accuracy), and that in 25 of 33 infarcted segments were correctly predicted to be irreversible (76% prediction accuracy) (p < 0.001). Similarly, among 53 asynergy segments assessed by radionuclide ventriculography, abnormal wall motion in 21 of 27 asynergy segments was correctly predicted to be reversible (78% prediction accuracy), and that in 21 of 26 PET viable segments was correctly predicted to be irreversible (81% prediction accuracy) (p < 0.001). Thus, preoperative metabolic imaging using PET appears to be useful for predicting responses to CABG.