This study is testing a new gene therapy to help people with a type of heart failure called non-ischemic cardiomyopathy. It is for adults (18+) who have heart failure symptoms and are stable on their current heart medications. The study uses a special method called intracoronary infusion to deliver the treatment directly into the heart. Participants will be split into three groups to receive either a low dose, high dose, or a fake treatment (placebo) to compare results.

The study will last for 52 weeks, with an additional 4 years of follow-up to check on long-term effects. Participants will need to visit the study center multiple times over the year and have regular phone check-ins during the follow-up period. The study will assess the safety and effectiveness of the treatment.

• The study lasts a total of 5 years, with 1 year of regular visits and 4 years of follow-up.
• Participants must be stable on their current heart medications before joining.
• Safety and effectiveness will be closely monitored throughout the study.