The role of non-invasive stress testing in the diagnosis of coronary microvascular disease

Background: Angina with non-obstructive coronary artery disease (ANOCA) is commonly observed in patients with stable angina undergoing coronary angiography. Current guidelines recommend non-invasive stress testing as the first step in diagnosing coronary microvascular disease (CMD). This study aims to evaluate the diagnostic value of noninvasive stress testing in patients invasively diagnosed with CMD. Methods: We conducted a retrospective analysis of prospectively collected data. Eligible subjects were patients with angina who underwent NIST evaluation (echocardiography/ electrocardiography stress test or single-photon emission computerized tomography) prior to coronary angiography. All patients underwent invasive evaluation of microvascular function, which included the assessment of Coronary Flow Reserve, Index of Microcirculatory Resistance, and Resistive Reserve Ratio. Results: Overall, 140 patients (77 women, 67 +/- 10 y/o) underwent NIST evaluation prior to coronary angiography, of whom 81 % were positive for ischemia. There was no difference in the prevalence of positive NIST between patients with abnormal compared with normal microvascular function tested invasively (81 % vs 82 %, p = 0.94). The prevalence of CMD was similar between patients with positive versus negative NIST (51 % vs 50 %, p = 0.94). Among 114 patients with positive NIST, 56 (49.2 %) had normal microvascular function, regardless of the type of stress test used (p = 0.94), the suspected territory of ischemia (p = 0.15), or the estimated severity of the ischemia (p = 0.63). Conclusion: Non-invasive stress testing may have a limited predictive value in the diagnosis of CMD in ANOCA patients. Larger prospective studies are required for better understanding of the role these tests in the diagnosis and definition of CMD.