Ejection fraction (EF) is an incomplete metric and requires consideration of an associated companion (EFC) metric. This figure is based on 96 cardiac patients, including those with acute myocardial infarction (MI). For mid-range EF (with values ranging from 40% to 50%) the brown-colored area indicates the distribution of the EFC for these patients. Only the combination of EF and EFC can define the unique location of each patient. Likewise, data points are spread for any other EF range, for example, those with 55<EF<60% (see yellow area). Volume data obtained by cardiac magnetic resonance imaging (courtesy of Prof. R. A. Diaz-Navarro).