Diagnostic testing to evaluate the potential for recovery of viable but dysfunctional myocardium has become an important component of the assessment of patients with chronic coronary artery disease (CAD) and left ventricular (LV) dysfunction, as bypass surgery or angioplasty are associated with an increased risk of mortality and morbidity in these patients. Single photon emission computed tomography (SPECT) as well as positron emission tomography (PET), can be used to investigate perfusion, cell membrane integrity, and metabolic activity, whereas dobutamine echocardiography can assess myocardial contractile reserve. Assessment of myocardial viability with thallium 201 imaging may provide critically important data for risk stratification and revascularization decision-making in patients with CAD and LV dysfunction, although this decision should also be based on clinical presentation, coronary anatomy, LV function, and evidence of inducible ischemia...