Measurement of myocardial beta-adrenoceptor density in clinical studies: a role for positron emission tomography?

Abstract

The beta-adrenoceptor (beta-AR) plays an important role in the regulation of heart function and has been extensively studied in recent decades. In vitro studies have shown down-regulation of beta-AR density in heart failure and cardiac conditions that may lead to heart failure. As in vitro measurements on cardiac tissue samples do not allow longitudinal and regional assessment of myocardial beta-ARs in humans, new methods are being developed to measure beta-ARs in vivo using positron emission tomography (PET). Studies using PET and the radioligand [(11)C]CGP 12177 have shown promising results that are in agreement with those of in vitro studies. However, the radiochemical synthesis of [(11)C]CGP 12177 is very demanding, preventing its widespread use. Hence, new radioligands are being developed using simpler methods of radiochemical synthesis. ( S)-[(11)C]CGP 12388 has been presented as a promising new radioligand. So far, in vivo measurements of beta-AR density using PET have mainly been performed to confirm in vitro studies. Using the full potential of PET, performance of regional measurements and longitudinal studies might add further knowledge on the pathophysiological role of the beta-AR in cardiac disease and the effect of interventions. Furthermore, PET might gain a role in the clinical management of patients with abnormalities of cardiac contractile function.