LAUSR

Suspected stable angina is a common presenting complaint, and the process of establishing the etiology of these symptoms consumes substantial diagnostic resources. Perhaps the greatest challenge relates to individuals with low to intermediate pretest probability for obstructive coronary artery disease. In these patients, additional noninvasive testing—either functional or anatomic—is frequently required to provide patients and clinicians alike with sufficient reassurance that invasive coronary angiography can be deferred. Demand for further investigation continues to grow despite falling baseline risk, and as a consequence, there has been a marked reduction in the prevalence of functionally significant coronary artery disease in patients undergoing stress imaging in recent years (1). Clearly then, there is a need to improve the selection of patients for whom further testing is necessary, and cardiac troponin appears a suitable candidate for such an indication. High-sensitivity assays allow accurate quantification of plasma or serum troponin concentrations in the majority of adults, and numerous studies have demonstrated the prognostic importance of troponin in primary prevention populations (2, 3) and among patients with a variety of stable (4, 5) and acute (6) cardiac disorders. Furthermore, when compared to the reference standard of obstructive disease identified on coronary computed tomography angiography, high-sensitivity troponin I assays have been shown to improve the accuracy of existing risk models for the estimation of pretest probability (7, 8). Within this context, Mueller et al. report in this issue of Clinical Chemistry on a large, well-conducted investigation that reinforces the potential diagnostic value of troponin in the setting of suspected inducible myocardial ischemia (9). An important strength is the use of the most widely available high-sensitivity troponin (hs-cTn) I and T assays with blinded classification of functionally relevant coronary artery disease (fCAD)4, determined from myocardial perfusion imaging with single-photon emission computed …