Steven R. Steinhubl, and Eric J. Topol JACC 2015;66:1489-1496 An Example of Clinically Important Subclassification of Phenotypes Three distinct subgroups developed through phenomapping of detailed clinical data in 397 patients with a diagnosis of heart failure (HF) with preserved ejection fraction. After adjustment for known risk factors, a patient’s subgroup was significantly associated with adverse outcomes. Data are from Shah et al. (17). CV = cardiovascular. Steven R. Steinhubl, and Eric J. Topol JACC 2015;66:1489-1496 American College of Cardiology Foundation