IMAGING ACE AND ANGIOTENSIN RECEPTORS IN THE HEART


Jamshid Shirani, M.D., St. Luke's Hospital and Health Network, Bethlehem, PA, USA

Angiotensin II (AII), an octapeptide member of the renin-angiotensin system (RAS), is formed by the enzyme angiotensin converting enzyme (ACE) and exerts adverse cellular effects through an interaction with its type 1 receptor (AT1R). Both ACE inhibitors and angiotensin receptor blockers (ARB) mitigate the vasoconstrictive, proliferative, proinflammatory, proapototic and profibrotic effects of AII and are widely used as effective antiremodeling agents in clinical practice. Prediction of individual response to these agents, however, remains problematic and is influenced by many factors including race, gender and genotype. In addition, systemic and tissue RAS activity do not correlate closely. Non-invasive determination of tissue ACE activity and AT1R expression using novel nuclear tracers may improve treatment of heart failure through more selective pharmacologic intervention and better dose titration of available drugs while avoiding unnecessary drug toxicity and side effects. Such imaging techniques would also be another step forward in attempts towards personalized approaches to management of advanced heart disease.