Background: Systemic sclerosis (SSc) is a disease that causes multisystem fibrosis and has a 10-year survival of 50-84%. Death is 5-15 times more likely when the heart is affected. Myocardial fibrosis in SSc may interfere with contraction, relaxation, and microvascular function, resulting in heart failure, ischemia, and arrhythmias. We sought to quantify the effects of SSc on the heart using cardiac magnetic resonance imaging (CMR). Methods: In 11 SSc patients and 11 patients with normal clinical stress perfusion CMR, we measured myocardial perfusion reserve (MPR, ratio of blood flow at stress versus rest), extracellular volume fraction (ECV, a measure of myocardial fibrosis), and left ventricular ejection fraction (LVEF, a measure of systolic function). Results: ECV was significantly higher (29.3±3.7% vs. 23.6±2.8%, p