Risk stratification using stress myocardial perfusion imaging: don't neglect the value of clinical variables.

A large amount of data has accumulated during the past 20 years demonstrating the value of exercise or pharmacologic stress planar and single-photon emission-computed tomographic (SPECT) perfusion imaging for risk stratification and prognostication in patients with suspected or known coronary artery disease (CAD) (1–14). The major goal of such noninvasive risk assessment is the identification of subsets of patients at high risk for subsequent cardiac death or nonfatal infarction who may benefit from prompt referral for cardiac catheterization with a view toward invasive strategies for revascularization (15). Conversely, patients deemed at low risk for subsequent cardiac events based on stress test and nuclear scan variables are treated medically and spared the premature or unnecessary referral for invasive evaluation, which also increases unduly the cost of diagnostic cardiology.