Selecting the best noninvasive imaging test to guide treatment after an inconclusive exercise test

The first step towards approaching a patient with an inconclusive stress test is to identify the initial reason why a stress test was ordered and examine what factors led to inconclusive test results. Next, it is important to ask whether the patient will benefit from further testing, as not all patients with inconclusive test results require additional testing. In patients who are at low-to-intermediate risk, it may be useful to perform coronary CT angiography (CTA) to exclude the presence of obstructive coronary atherosclerosis. Among individuals with no prior history of coronary artery disease, a possible advantage of CTA is that if subclinical atherosclerosis is identified, intensification of lifestyle interventions, and often pharmacotherapy, should be advocated. On the other hand, in high-risk patients or individuals that already have coronary artery disease, the primary objective is to quantify the presence and magnitude of ischemia in order to define the potential role of coronary revascularization procedures. This can be achieved by myocardial perfusion imaging using nuclear imaging or cardiac MRI. Alternatively, a functional evaluation to identify stress-induced wall motion abnormalities using stress echocardiography or MRI can be obtained. In selecting which test to obtain, it is important to understand the strengths and limitations of different imaging tests and to consider patient factors (e.g., body habitus) that may influence the accuracy of various tests. In addition, physicians should consider whether there are any other clinical questions that require imaging. For instance, cardiac MRI may be used to evaluate for infiltrative myocardial disease or pericardial disease whereas cardiac CT can evaluate for lung pathology or diseases of the aorta. Finally, any decision regarding what type of additional testing to obtain should also be based on knowing the local expertise and availability of various testing options.