Recent Developments in Imaging of Myocardial Angiotensin Receptors

Upregulation of the systemic and myocardial renin-angiotensin system (RAS) plays a role in adverse left ventricle (LV) remodeling and development of heart failure in various cardiac diseases. Treatment with RAS inhibitors can reduce LV remodeling and improve clinical outcomes. Since there are significant differences in the activation levels of myocardial and systemic RAS, a monitoring system of the RAS activation at tissue level could be useful. Molecular imaging of increased myocardial angiotensin converting enzyme (ACE) activity or angiotensin II type 1 –receptor (AT1R) upregulation might identify patients at risk of developing heart failure or optimize treatment of heart failure. Experimental studies using PET and SPECT imaging with radiolabeled ligands have shown feasibility of non-invasive detection of ACE or AT1R upregulation in the heart after myocardial infarction. In the current article, the recent advances and new tracers for molecular imaging of myocardial RAS activation are reviewed together with the discussion on patophysiology and the potential clinical implications.