Prognostic utility of ischemic response in functional imaging tests (SPECT or stress echocardiography) in low-risk unstable angina patients

Background: The aim of this study is to determine the ability of ischemic response in imaging stress tests (single-photon emission computed tomography [SPECT] or stress echocardiography [SE]) to predict events in low-risk unstable angina patients. Methods: Three hundred and fifty-nine patients with unstable angina (< 24 h), asymp­tomatic at admission, without ST-segment elevation or depression, normal troponins, and undergoing SPECT (n = 188) or SE (n = 171) during hospitalization (median = 1 day) were included. A positive imaging test (IMAGING+) was defined as the presence of reversible perfusion defects or wall motion abnormalities in at least 2 contiguous segments. Multivariate models were constructed using these results and clinical variables to predict events at 6 months. Results: Ninety-nine (27%) patients had IMAGING+, 72/188 (38%) in SPECT and 27/17 (16%) in SE (p < 0.0001). Events occurred in 84 (23%) patients: 4 had myocardial infarc­tion, 47 new hospitalizations due to angina and 33 coronary artery revascularizations. Inde-pendent predictors of coronary artery disease were: IMAGING+ (OR: 6.4, 95% CI: 3.4–11.8, p < 0.0001), history of coronary artery disease (OR: 2.5, 95% CI: 1.2–5.2, p < 0.02) and TIMI risk (OR: 1.5, 95% CI: 1.1–2.2, p < 0.03). Conclusions: In low-risk unstable angina patients, an ischemic response in functional stress tests (SPECT or SE) was associated with adverse events and severe coronary artery disease