Advances in Cardiovascular Imaging Ischemic Burden, Treatment Allocation, and Outcomes in Stable Coronary Artery Disease

Chronic stable angina is the most common clinical manifestation of ischemic heart disease, affecting as many as 54 million people globally, and more than 10 million people in the United States.1 It is therefore remarkable that after many decades of research, the optimal strategy for management of this common condition remains unclear. In particular, the indications and relative benefits of revascularization have been a source of contention. This is in clear contrast to the situation in patients with unstable coronary syndromes, where the evidence for revascularization is much more clearly defined.2 The results of 2 recent randomized trials for the management of mild-moderate chronic stable angina (COURAGE and BARI-2D) have stimulated vigorous debates regarding the role of revascularization versus a conservative approach of initial optimal medical therapy (MT).3–6 These trials showed that in selected patients who were randomly assigned after angiography, rates of death and myocardial infarction did not differ between revascularization and medical therapy. The efficacy of revascularization for the small minority of patients who have severe symptoms or significant angiographic left main disease is widely accepted, and these cases have been excluded from these studies. However, a major issue that remains unresolved is the applicability of these data to patients seen in daily clinical practice who may not have undergone angiography, and in particular, the role of assessing ischemic burden using stress testing in allocation of treatment. These patients have mild-moderate symptoms and either do not have significant left main disease, or, more commonly, have not had coronary angiography performed. In this patient group, which constitutes the majority of patients with chronic stable angina, most clinicians use an ischemiabased treatment strategy, with those who have more severe ischemia being considered for revascularization. Although this approach is recommended by the guidelines and is widely practiced, there are currently no prospective randomized data to support it. In this state-of-the-art article, we give a critical overview of the role of stress imaging for measuring ischemic burden and ischemia change in the management of patients with chronic stable angina.