Evaluation of patients with acute chest pain using SPECT myocardial perfusion imaging: Prognostic implications of mildly abnormal scans

Background: While patients presenting to emergency departments (ER) with chest pain are increasingly managed in chest pain units (CPU) that utilize accelerated diagnostic protocols for risk stratification, such as single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), data are lacking regarding the prognostic implications of mildly abnormal scans in this population. Objectives: To evaluate the prognostic implications of mildly abnormal SPECT MPI results in patients with acute chest pain. Methods: Of the 3753 chest pain patients admitted to the CPU at the Leviev Heart Center at Sheba Medical Center between 2006 and 2010, 1593 were further evaluated by SPECT MPI. Scans were scored by extent and severity of stress-induced perfusion defects, with 1221 patients classified as normal, 82 with myocardial infarction without ischemia, 236 with mild ischemia, and 54 with more than mild ischemia. Mild ischemia patients were further classified to those who did and did not undergo coronary angiography within 7 days. Results: Mild ischemia patients who underwent coronary angiography were more likely to be male (92% vs. 81%, P = 0.01) and to have left anterior descending ischemia (67% vs. 42%, P = 0.004). After 50 months, these patients returned less often to the ER with chest pain (53% vs. 87%, P < 0.001) and had a lower combined endpoint of acute coronary syndrome and death (8% vs. 16%, P < 0.001). Conclusions: Compared to patients with chronic stable angina, patients presenting with acute chest pain exhibiting mildly abnormal SPECT MPI findings should perhaps undergo a more aggressive diagnostic and therapeutic approach.