Heart failure with preserved ejection fraction (HFpEF), a certain type of heart failure, occurs when the heart doesn't pump blood around the body properly. It can cause breathlessness, tiredness, and swollen feet or ankles. It is not clear why people develop HFpEF and treatment options are very limited. TRAITS-HFpEF is a study that aims to understand why people develop HFpEF, identify new tests and treatments, and gain information on the life expectancy of people living with this condition. It will do this by routinely collecting information on people attending a specialised outpatient HFpEF clinic.