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INTRODUCTION

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Contemporary patients with coronary artery disease have a very good survival, primarily due to effective therapies including cardiac medications, appropriate interventions such as coronary bypass graft surgery (CABG) and percutaneous coronary interventions (PCI), and successful treatment for acute myocardial infarction. The decision to undergo an imaging evaluation after one or more of these therapies is an important one, particularly if the patient is asymptomatic. This chapter will evaluate the role of stress MPI in patients with stable CAD under multiple settings including medications, those post-interventions, and patients sustaining myocardial infarction.

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MYOCARDIAL PERFUSION IMAGING AND CHRONIC ISCHEMIC HEART DISEASE

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Indications for Stress Myocardial Perfusion Imaging

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Exercise stress testing alone is an important tool in following patients with known coronary disease, especially whenever there is a change in the frequency or pattern of symptoms. However, several factors may preclude use of exercise stress testing alone as the diagnostic modality to make further decisions. The American College of Cardiology/American Heart Association (ACC/AHA) guidelines for exercise testing1 strongly recommend an imaging study as part of the evaluation in patients unable to exercise and in those with baseline EGG abnormalities (preexcitation, paced ventricular rhythm, >1 mm of resting ST depression, and complete left bundle branch block [LBBB]). The use of digoxin, presence of left ventricular hypertrophy (LVH), or any resting ST-segment depression decreases the specificity of exercise testing while sensitivity may remain unaffected.1 Several other subsets of patients benefit incrementally with the use of radionuclide imaging. Those groups involve patients with previous MI and/or revascularization procedures (CABG or PCI), patients with prior angiography demonstrating significant disease (where identification of lesion-causing myocardial ischemia is important), high-risk individuals for future events (e.g., diabetics), and patients with a previous positive nuclear scan.1,25 A summary of the conditions in which radionuclide perfusion imaging is preferred over conventional exercise stress testing is presented in Table 17-1.6

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Table Graphic Jump Location
Table 17-1Indications for the Use of Radionuclide Perfusion Imaging Rather than Exercise Electrocardiography*

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