In patients with known coronary artery disease (CAD), abnormal single-photon emission computed tomography (SPECT) or positron emission tomography (PET) myocardial perfusion imaging (MPI) is associated with an increase in risk of adverse cardiac events, proportional to the extent and severity of the perfusion abnormalities.
SPECT and PET MPI can determine extent, severity, and localization of perfusion abnormalities in patients with multivessel CAD or prior revascularization procedures, guiding management strategies.
Routine MPI testing after coronary revascularization in patients with stable or no symptoms is not supported by current guidelines.
SPECT and PET MPI provide safe and effective risk stratification in patients presenting with acute coronary syndromes or myocardial infarction who have not received or have a contraindication to invasive coronary angiography.
SPECT and PET MPI can be useful to assess response to medical therapy in patients with established CAD.
In recent decades, there has been a dramatic decline in the rate of death attributable to cardiovascular disease.1 This trend is credited primarily to the development and implementation of effective treatment strategies, including medical therapy, interventions such as coronary artery bypass graft (CABG) surgery and percutaneous coronary interventions (PCI), and successful treatment for acute myocardial infarction. With these advances in mind, the decision to undergo myocardial perfusion imaging (MPI) evaluation in patients with known ischemic heart disease is an important one, particularly in asymptomatic patients. This chapter will evaluate the role of stress MPI in patients with known coronary artery disease (CAD) in a variety of settings, including medical therapy, postinterventions (CABG, PCI), and following myocardial infarction.
MYOCARDIAL PERFUSION IMAGING AND CHRONIC ISCHEMIC HEART DISEASE
Indications for Stress Myocardial Perfusion Imaging
Stress testing is an important tool in the longitudinal assessment of patients with known CAD, especially when there is a change in the frequency or pattern of symptoms. Once the decision has been made to further assess the patient, the choice comes to stress with or without imaging. The use of exercise tolerance testing (ETT) without imaging to make management decisions in this patient population requires several important considerations. The American College of Cardiology/American Heart Association (ACC/AHA) guidelines for ETT strongly recommend an imaging study as part of the evaluation in patients with baseline EGG abnormalities (pre-excitation, paced ventricular rhythm, ≥1 mm resting ST-segment depression, and complete left bundle branch block [LBBB]).2 In addition, in the CAD population, over 60% of candidates for stress are unable to complete an exercise protocol, therefore requiring pharmacologic stress with imaging. The use of digoxin, presence of left ventricular hypertrophy, or any resting ST-segment depression decreases the specificity of exercise testing, while sensitivity may remain unaffected.2 Importantly, several other subsets of patients benefit incrementally with the use of radionuclide imaging, including patients with previous myocardial infarction (MI) and/or coronary revascularization procedures (CABG or PCI), patients with prior angiography demonstrating significant disease (where identification of the ...