Value based imaging for coronary artery disease: Implications for nuclear cardiology and cardiac CT

Abstract

Technology in cardiac computed tomography (CT) and nuclear cardiology is constantly improving. In single photon emission CT (SPECT), new cameras, reconstruction methods, and protocols have dramatically reduced radiation doses to patients. In positron emission tomography (PET), application of quantitative measurements of myocardial perfusion reserve is improving assessment of prognosis. PET/CT is routinely performed in conjunction with coronary artery calcium (CAC) scanning in many centers, extending the ability of myocardial perfusion imaging (MPI) studies to impact patient management. In cardiac CT, marked improvements in equipment and reconstruction software have also dramatically reduced the patient radiation associated with cardiac testing, and have reduced the frequency of non-diagnostic studies. New methods for combining anatomic and functional assessment with CT-CT perfusion and FFR CT measurements-are beginning to be used clinically. With the expanding capabilities of each technology, their opportunities to provide value increases. Given the changing reimbursement paradigm from a volume-based to a value-based system, the applications of each technology that will survive are those that improve relationship between outcomes and costs. With respect to coronary artery disease (CAD), a growing body of evidence exists regarding the value of specific tests in the various clinical settings in which CAD is considered. For prevention, data is strong in that CAC scanning can provide value by improving outcomes. In the patient with acute chest pain, CCTA appears to be able to shorten time in the hospital and reduce costs. In patients with suspected stable ischemic heart disease and an intermediate pre-test likelihood of CAD, the use of CCTA appears to be valuable. In patients who have known CAD or in whom a nondiagnostic CCTA is likely, improvement in outcomes based on CCTA is less likely and testing for ischemia may be preferred. In patients with a very high likelihood of CAD or known CAD, registry data suggests that ischemia testing, such as that provided by SPECTor PET-MPI studies, may improve outcomes by improving selection of patients for revascularization. The ISCHEMIA trial will test whether a strategy basing decisions for revascularization on noninvasive assessment of ischemia improves outcomes. Test selection is highly dependent on accurate pretest risk assessment. An updated method for assessment of pre-test risk has developed which may lead to improved utilization of cardiac imaging procedures. In all of the applications of noninvasive imaging, value can only be achieved if the appropriate patients are selected for testing and if the test result changes management, such that outcomes can be improved or costs reduced.