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BACKGROUND

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Coronary artery disease (CAD) remains the single greatest cause of death of men and women in the United States, despite a declining total death rate. Using 2005 data, over 445,000 (or 1 in every 5) deaths were due to CAD and it ranked highest among all disease categories in hospital discharges.1 In 2009, an estimated 785,000 Americans had a new coronary event. The estimated direct and indirect costs of CAD in 2008 are over $50 billion.2 The reduction of the morbidity and mortality due to CAD is thus of primary importance to physicians and patients. This has spurned a great interest in identifying those patients who can benefit from preventive and therapeutic strategies. Stress myocardial perfusion imaging (MPI) has emerged as an important non-invasive means of evaluating patients with suspected CAD, with over 8.5 million studies performed annually.3 This chapter will discuss the diagnostic accuracy of stress MPI and how to decide which patients should undergo stress MPI for suspected CAD. Options for the type of stress with MPI and their uses in appropriate patients will also be reviewed.

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Patients with suspected CAD need to be assessed in a stepwise fashion, which includes risk factor analysis, assessment of the risk for significant CAD, and assessment of the risk for having any of the devastating outcomes of CAD, particularly myocardial infarction (MI) and cardiac death.

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RISK FACTOR ASSESSMENT

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The first step in evaluating patients for CAD involves the assessment of the presence of traditional risk factors. Modifiable risks include hypercholesterolemia, tobacco use, hypertension, diabetes mellitus, physical inactivity, and obesity. Non-modifiable risk factors include a family history of CAD in first-degree relatives under the age of 60 years, advanced age, and male gender.4 Clinical prediction models have been developed to stratify patients into low, intermediate, and high risks of CAD and cardiac death based on the presence of these risk factors.5,6 Gender-specific functions of the Framingham CAD prediction model have been validated in whites and blacks, although the model tends to overestimate the risk of cardiac events in other ethnic groups.7 In the Framingham model, total risk is defined as angina pectoris, recognized and silent MI, unstable angina, and cardiac death. More recent reports from the Framingham study include risk estimates for "hard" CAD, which excludes angina pectoris, but includes unstable angina and silent MI (defined by electrocardiographic findings). A modified version of the Framingham risk score has been incorporated into the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III).8

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A gender-specific multivariable risk factor algorithm based on the Framingham model has been proposed that can be used to assess general CVD risk and risk of CVD events (coronary, cerebrovascular, and peripheral arterial disease and heart failure).9 This is a useful tool for physicians to assess ...

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