Reassessing the Role of Ischemia Imaging: Insights from the ISCHEMIA Trial.

Ischemia imaging plays an important role in prognostication as well as guiding decision for revascularization with known CAD, as shown in multiple observational registries. However, results from the ISCHEMIA trial (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches) presented conflicting results, hinting at no survival benefit after revascularization in patients with moderate to severe ischemia on nuclear imaging. More recent analysis from the trial did, however, show decrease in cardiac mortality and increase in non-cardiac mortality following early revascularization. However, the ISCHEMIA trial has several limitations; most importantly, the trial design does not support a comparison between imaging modalities. Additionally, results of the trial do not apply to patients with previous CABG or ACS as they are exclusion criteria, which affects the diagnostic accuracy of nuclear stress imaging. Observational imaging registries offer better evidence about the accuracy of single-photon emission computed tomography (SPECT) and positron emission tomography (PET) in guiding revascularization for patients with ischemia. Results from ISCHEMIA trial can be used to guide management of patients with severe to moderate ischemia, provided they meet inclusion criteria. For those who do, shared decision-making is important to decide between invasive management or optimal medical therapy only.