Eligible participants will undergo a one-time antegrade epicardial coronary artery infusion of gene therapy delivered to the 3 major cardiac territories of the left ventricle of the heart (anterior, lateral, inferior/posterior) or bypass grafts unless contraindicated. Post-procedure, the subject will be monitored continuously for a minimum of 4 hours and then discharged to home that same day if medically appropriate. Participants will be followed for 52 weeks as part of the main trial. On Day 2 and Week 1, subjects will be contacted by phone for a general safety assessment, and if clinically indicated, an in-person evaluation and assessment will be performed as soon as possible. On Weeks 2, 4, 12, 24 and 52, subjects will undergo general safety assessments. Additionally, at Weeks 24 and 52, subjects will undergo outpatient core resting and exercise transthoracic echocardiography, right heart catheterization with hemodynamic monitoring and gas exchange measurements, 6-minute wall test, cardiac biomarker testing and completion the Kansas City Cardiomyopathy Questionnaire. Upon completion of the active observation period, participants will continue to be followed for 4 years with bi-annual, semi-structured telephone or in-person questionnaires that collect information on overall status and other comorbid conditions of interest in gene therapy trials.