In October 2019, FDA pursued a study in the Sentinel System to describe utilization patterns for spironolactone in patients with heart failure (HF) with preserved ejection fraction (HFpEF). The study was initiated as the FDA Center for Drug Evaluation and Research (CDER) Division of Cardiology and Nephrology was considering data from a clinical trial sponsored by the National Institutes of Health (NIH) that found a significantly lower incidence of heart failure (HF) hospitalization among HFpEF patients treated with spironolactone compared to placebo. To characterize the real-world utilization of spironolactone in patients with HFpEF, and in patients with HF with reduced ejection fraction (HFrEF), FDA conducted a study in the Sentinel System. The study identified 2,009,529 patients with HFrEF and 9,257,514 HFpEF patients. The proportion of patients initiating spironolactone was 20.7% after HFrEF diagnosis versus 7.6% after HFpEF diagnosis. The median time (days) to initiation of spironolactone after HFrEF diagnosis was 90 (IQR: 19–385) and after HFpEF diagnosis was 286 (IQR: 57–851). The median duration (days) of first treatment episode in HFrEF patients was 120 (IQR: 44–321) and for HFpEF patients was 114 (IQR: 32 – 301). The median dose was similar (25mg/day) for both HF cohorts. This study characterized the use of spironolactone in a large database with demographically and geographically diverse patients. While there was lower initiation of spironolactone following HFpEF compared to HFrEF diagnosis, the dosing and duration of the first continuous spironolactone episode were similar. As a result of this study, no regulatory action was taken.