eHealth Lifestyle Intervention To Enhance Outcomes in HFpEF

The goal of this clinical trial is to learn if a digital lifestyle education program improves exercise capacity in adults who have heart failure with preserved ejection fraction (HFpEF) and overweight or obesity. HFpEF is a type of heart failure in which the heart muscle is stiff and does not relax well, even though its pumping strength looks normal. The main questions it aims to answer are:

* Does the program improve how much oxygen participants can use during exercise, a measure of fitness, after 6 months? * Does the program improve participants' quality of life and help them lose weight?

Researchers will compare a group that uses the digital program plus usual care to a group that receives usual care alone. This will show whether the program adds a benefit.

Participants will:

* Be placed by chance into one of the two groups * Use a study website with short videos on exercise, healthy eating, and managing stress (program group), with new content every week for 6 months * Have exercise tests, an ultrasound scan of the heart, blood tests, and complete a quality-of-life questionnaire at the start and after 6 months

Both groups will keep taking their usual heart failure medicines.