For many patients with chronic coronary artery disease, risk stratification as to likelihood of cardiac death lays at the basis of choosing between the two major therapeutic options of medical management or revascularisation. The target population is those with an intermediate risk of cardiac death, as patients known to be at high or low risk are already adequately risk stratified for clinical decisions. Perfusion imaging is frequently used for these purposes because it can separate patients into low (< 1%), intermediate (1–3%), and high (> 3%) likelihoods for the major coronary events. In general, contemplation for revascularisation therapy for patients with mild to moderate symptoms would depend on the likelihood of a major coronary event being greater than 3% per year, in whom revascularisation may confer a survival advantage. Someone with a < 1% annual event rate might best be managed medically, as the mortality for patients undergoing revascularisation procedures is at least 1%. Management of patients whose perceived risk of a major coronary event is in the range of 1–3% annually will be individualised, considering such factors as age, compliance with important medications known to reduce risk (such as statins, angiotensin converting enzyme (ACE) inhibitors, β blockers), and willingness to undergo periodic follow up.

NUCLEAR CORRELATES OF PROGNOSIS

Perfusion imaging has value in risk assessment because it permits quantitative assessment of stress induced myocardial perfusion and, if ECG gated single photon emission computed tomography (SPECT) is used, left ventricular function. In patients with known or suspected coronary artery disease a normal perfusion scan is very valuable because it indicates a benign prognosis. Between 1994 and 2001, 16 different studies, including approximately 21 000 patients with a normal perfusion study (fig 1) and mean follow up of 28 months, were reported¹; the rate of cardiac death or of myocardial infarction was less …