Anatomic and Functional Assessment of Coronary Artery Disease

Between two worlds life hovers like a star, twixt night and morn, upon the horizon’s verge. — —Lord Byron Conventional noninvasive methods of evaluation of individuals with suspected coronary artery disease (CAD) have relied on functional testing by an array of modalities, including exercise treadmill testing, stress echocardiography and myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT),1 or positron-emission tomography (PET).2 In their most commonly used applications, these modalities are useful for assessing myocardial perfusion and function at rest and in response to exercise or pharmacological intervention, providing valuable information regarding the presence or absence of obstructive CAD, future cardiac events, and predicting benefit from appropriate therapies.Article see p 174 Among the wide range of functional imaging tests, SPECT-MPI has emerged as the most commonly used modality—accounting for nearly 90% of imaging stress tests performed in the United States each year.3 Early studies examining SPECT indicate that myocardial perfusion is reduced in the presence of a ≥70% intraluminal epicardial stenosis.4 Beyond its diagnostic potential, the widespread use of SPECT-MPI stems from its robust ability for prognostic risk stratification, such that individuals with normal SPECT have very low rates of near- and intermediate-term adverse CAD events, whereas those with severely abnormal SPECT-MPI have high rates of adverse CAD events.5 Further, SPECT may identify patients who may most benefit from invasive coronary angiography (ICA) and coronary revascularization in addition to medical therapy versus those who would benefit from medical therapy alone.6,7After early validation as a sensitive method for assessing reduction in coronary flow reserve,8 PET-MPI has also become a clinically useful method for the same applications as SPECT-MPI, adding higher resolution imaging and the ability to image ventricular function during peak stress.9,10 Given its ability for high count-rate dynamic studies, …