Celladon Corporation (Celladon) is investigating gene transfer as a method to restore calcium ion (Ca++) cycling in HF patients. The gene therapy vehicle uses a recombinant adeno-associated viral vector (AAV), which consists of an AAV serotype 1 capsid and contains the human sarcoplasmic reticulum Ca++ ATPAse (SERCA2a) complementary DNA (cDNA) flanked by inverted terminal repeats derived from AAV serotype 2 (AAV1/SERCA2a). MYDICAR® refers to AAV1/SERCA2a drug product intended for administration by percutaneous delivery. Phase 1/2 clinical trials have demonstrated initial safety and evidence of improvement in clinical outcomes at MYDICAR doses of up to 1 x 10^13 DNase-resistant particles (DRP). The trial described here is designed to investigate the safety profile and preliminary activity of MYDICAR at a dose of 2.5 x 10^13 DRP; this dose is 2.5-fold higher than previously investigated doses.