Exercise is the preferred modality for stress testing, whenever possible.
Pharmacologic stress myocardial perfusion imaging (MPI) has been well validated when compared to exercise MPI in terms of diagnostic accuracy and risk stratification.
Caffeine or aminophylline should be used to reverse adverse effects associated with vasodilator pharmacologic stress.
Adjunctive exercise with pharmacologic stress reduces side effects, enhances image quality, and improves the detection of myocardial ischemia.
Regadenoson is the most commonly used vasodilator in pharmacologic stress testing, with outstanding clinical value, ease of administration, and reduced side effects.
Beta blockers and other antianginal medications should usually be withheld prior to exercise and pharmacologic stress testing. Recent studies, however, have shown that if not feasible to hold beta blockers prior to pharmacologic MPI, testing is still possible with similar results.
Using radiopharmaceuticals to visualize the regional distribution of myocardial perfusion during rest and stress is a well-established modality for the evaluation of known or suspected coronary artery disease (CAD). In 1964, the first scintigraphic images of myocardial perfusion were acquired by Carrea et al.,1 while Zaret et al. were the first to demonstrate exercise-induced myocardial ischemia using radioactive potassium in 1973.2 Since then, the field of nuclear cardiology has grown dramatically, and numerous studies have validated the utility of both exercise and pharmacologic stress myocardial perfusion imaging (MPI) for risk assessment and the prediction of future cardiac events. With more than 8 million such studies being performed yearly in the United States alone and an estimated 15 to 20 million worldwide, understanding the logistics of and options available for radionuclide stress testing is critical.3,4
This chapter will discuss various forms of stress testing, including exercise and pharmacologic stress protocols, in conjunction with MPI. Information about the benefits and limitations of each method will be presented along with information to optimize the value of stress protocols with regard to safety and efficacy.
Whenever possible, exercise is the preferred modality for stress testing, because it allows for a physiologic assessment of functional capacity, hemodynamics, and symptoms. In addition, when compared to pharmacologic stress testing, exercise is associated with less extensive hepatic and gastrointestinal tracer uptake, which significantly improves image quality.5,6
MPI in conjunction with exercise stress testing enhances diagnostic sensitivity and specificity, particularly among patients with resting electrocardiographic (ECG) abnormalities that preclude the interpretation of ST-segment deviation. Similarly, MPI can differentiate true-positive from false-positive ST-segment depression (STD), which is helpful, because among patients referred for exercise ECG testing with a low to intermediate pretest probability of CAD, approximately 40% of those who develop STD will not have CAD.7 When compared to ECG interpretation in isolation, MPI not only provides a more accurate assessment of the extent and severity of disease, but can also localize ischemia to a particular vascular distribution. MPI is also useful when patients fail ...