Heart Transplant Myocardial Fibrosis Study

Primary purpose of the trial is to assess the effect of spironolactone on improving heart function, and its ability to reduce the amount of fibrosis (scar tissue) in the transplant heart of patients who have evidence of stiff hearts and therefore likely have increased scar tissue in the hearts. The investigators including cardiologists seeing the participants in the outpatient clinic and performing the cardiac biopsies and coronary sinus blood sampling, nursing staff involved in the heart transplant outpatient clinic, the cardiologists reporting on the Echocardiograms and Cardiac MRI; and the pathologists reporting on the blood investigations will be blinded to the treatment arm that the patient has been randomized into. The research study pharmacist will be performing the randomization from the Pharmacy department at The Alfred Hospital, and records of patient randomization will be stored in a sealed envelope for the duration of the patient's involvement in the trial, but accessible in case it becomes medically necessary (eg for adverse effects) to withdraw the patient from the trial and unblind them.