The incidence of congestive heart failure (CHF) has progressively increased over the last 25 years with coronary artery disease being the aetiology in 66% of patients with CHF. Assessment of myocardial perfusion and glucose uptake using PET imaging with 18F-FDG for metabolism and 13-N-ammonia or 82-rubidium for coronary flow has proven to be the gold standard for predicting the recovery of regional and global left ventricular (LV) function following revascularization. Patients with viable ischemic myocardium identified by a flow/metabolism mismatch, represent an especially high risk subgroup for hard coronary events within one year, in the absence of myocardial revascularization. The state of the art assessment of myocardial viability in the new millennium is an optimally glucose loaded PET myocardial perfusion/metabolic study. For patients with critically depressed LV function with LVEF <20% at rest assessment of contractile reserve, in addition to 18F-FDG-PET viability imaging, may help predict a favourable surgical outcome.