Heart failure with preserved ejection fraction (HFpEF) is common and increasing in prevalence. Despite this, HFpEF is challenging to diagnose due in part to its shared clinical features with other comorbid conditions. HFpEF is now understood as a systemic syndrome, often driven by pro-inflammatory comorbidities, rather than solely a cardiac disease. This review summarizes the epidemiology, diagnostic criteria, and pathophysiology of HFpEF and proposes a clinical approach for patients suspected of having or diagnosed with HFpEF.