Heart failure with preserved ejection fraction (HFpEF) causes hospitalizations, premature mortality and high health care costs. This is also due to poor understanding of HFpEF pathogenesis and, thus, lack of specific therapies. Prompted by the recent demonstration that HFpEF clusters different clinical phenotypes, the investigators propose that these phenogroups are driven by distinct myocardial abnormalities. Cardiac Magnetic Resonance (CMR) can help filling this gap in knowledge: on top of providing gold standard measurements for myocardial volume and cellular mass, recent technical advantages mean that this test can assess and quantify left ventricular extracellular volume, fibrosis and microvascular function accurately and non-invasively. In HFpEF patients, the investigators aim at assessing 1) the coronary microvascular function impairment; 2) the myocardial fibrotic burden; - seeking to understand the disease in order to improve care and cardiovascular outcomes for these patients.