Modulation of SERCA2a of Intra-myocytic Calcium Trafficking in Heart Failure With Reduced Ejection Fraction

This study is testing a gene therapy approach that targets a protein called SERCA2a in the heart, which helps regulate calcium and allows the heart to beat properly. The goal is to see if this therapy can improve heart function in patients with severe, chronic heart failure. **You may be eligible if...** - You have chronic heart failure (ischemic or non-ischemic) with severely reduced heart pump function (LVEF ≤35%) - You are in NYHA class III or IV (significant symptoms with minimal or no activity) - You are already on maximum recommended heart failure medications and have an implanted defibrillator (ICD) **You may NOT be eligible if...** - You have a specific type of cardiomyopathy such as restrictive, hypertrophic, amyloidosis, or myocarditis - You have had a prior heart transplant or certain prior heart surgeries - You have uncontrolled thyroid disease - You have certain serious kidney, liver, or other organ problems Talk to your doctor to see if this trial is right for you.