Around 375,000 Canadians live with heart failure with reduced ejection fraction (HFrEF). HFrEF worsens quality of life, and leads to hospitalizations and death. There is no cure for HFrEF, but it can be managed with medications. Many people with HFrEF are unaware of the medications available to treat HFrEF and do not receive the best medications for them. Decision aids are tools that can help inform patients about available treatment options so they can be better involved in shared decisions about their health. This study will be conducted at UBC and will recruit from five Canadian HF clinics. This study will help us better understand what matters most to people with HF when making decisions about their medications, and use this to develop an effective decision aid to support shared decision-making. To do this, we will conduct interviews of people with HF and their healthcare professionals. After this, we will ask people with HF to complete a special online survey called a discrete-choice experiment to understand what matters most to them, and by how much, when making decisions about their HF medications. Then, we will develop a web-based decision aid and test how it improves the quality of medication-related decisions and quality of life.