There is substantial evidence that many patients with impaired left ventricular function secondary to coronary artery disease may have hibernating or stunned myocardium. The identification of these patients is important, as revascularisation is associated with an improvement in function, and there is some evidence that revascularisation of these patients will actually improve prognosis. The most useful investigations for the identification of reversible left ventricular dysfunction are dobutamine echocardiography, thallium scanning and, although not available in many centres, PET scanning.