Single-photon emission computed tomography perfusion imaging: is using a "warranty period" warranted?

Warranty Period: What Do We Expect From SPECT? As single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has reached scientific and clinical maturity, we have grown to expect that the results of this test when negative, reliably predicts an excellent patient outcome. Typically, less than 1% of patients with a normal study will have a “hard” cardiac event, defined as myocardial infarction or cardiac death, but that 1% can be shortened or lengthened based on the presence of coronary artery disease (CAD), cardiac symptoms, age, sex, the need for pharmacological stress, and coronary risk factors such as diabetes mellitus. The time variability was assessed by Hachamovitch et al,1 and termed the “warranty period” for a normal SPECT MPI, defined the time to 1% risk of a cardiac event per year.