To the Editor: A 47-year-old woman with systemic lupus erythematosus (SLE) was referred for evaluation of persistent chest pain, characterized as pressure-like substernal pain, associated with shortness of breath and palpitations, worse with exertion, but also occurring at rest, not related to food or body positioning. Medications included hydroxychloroquine, candesartan, and intermittent methylprednisolone for SLE flares, most recently treated 4 months prior to the current office visit. Vital signs, physical examination, and echocardiogram were normal. Computed tomography angiography demonstrated normal coronary arteries without evidence of plaque or calcification. However, an adenosine stress cardiac magnetic resonance imaging (CMRI) perfusion study demonstrated nearly circumferential subendocardial hypoperfusion (Figures 1A, 1B) without evidence of abnormality on T2 or delayed enhancement (DE; Figure 2, A1 and A2) and with a calculated left ventricular ejection fraction (LVEF) of 70%. Selective left coronary angiography, as part of the research protocol, demonstrated no obstructive coronary artery disease (CAD; Figure 3). Coronary reactivity testing showed an abnormal coronary flow reserve of 1.35 (normal > 2.5) in response to intracoronary adenosine, consistent with microvascular coronary dysfunction. Therapy with low-dose aspirin, statin, and carvedilol was initiated, with improvement in chest pain symptoms. Figure 1. First-pass perfusion images through the short axis, 2-chamber views. The images show normal myocardial enhancement at rest (B, D, F) and … Address correspondence to Dr. C.N. Bairey Merz, Cedars-Sinai Medical Center, 444 S. San Vicente Blvd., Suite 600, Los Angeles, CA 90048, USA. E-mail: noel.baireymerz{at}cshs.org.