Myocardial b-Adrenergic Receptor Density Assessed by 11C-CGP12177 PET Predicts Improvement of Cardiac Function After Carvedilol Treatment in Patients with

We evaluated whether myocardial b-adrenergic receptor (b-AR) density, as determined by 11C-CGP12177 PET, could predict improvement of cardiac function by b-blocker carvedilol treat-ment in patients with idiopathic dilated cardiomyopathy (IDC). Methods: Ten patients with IDC (left ventricular ejection fraction [LVEF] , 45%) were studied. Myocardial b-AR density was es-timated using 11C-CGP12177 PET before treatment with carve-dilol. Changes of LVEF in response to dobutamine infusion (DLVEF-dobutamine) were also measured by echocardiography. Changes of LVEF (DLVEF-carvedilol) were evaluated after 20 mo of carvedilol treatment. Results: Baseline myocardial b-AR den-sity significantly correlated with DLVEF-carvedilol (r 5 20.88, P, 0.001). In contrast, DLVEF-dobutamine did not correlate with DLVEF-carvedilol (P5 0.65).Myocardialb-ARdensitywas the sig-nificant multivariate independent predictor of DLVEF-carvedilol (b 5 20.88, P, 0.001) among univariate predictors, including functional class (r 5 0.76, P, 0.05), plasma norepinephrine (r 5 0.85, P, 0.01), LVEF (r520.64, P, 0.05), and age as confound-ing factors. Furthermore, myocardial b-AR density was signifi-cantly correlated with plasma norepinephrine (r 5 20.79, P, 0.01) and LVEF (r 5 0.70, P, 0.05). Conclusion: Myocardial b-AR density is more tightly related to improvement of LVEF-carvedilol than is cardiac contractile reserve in patients with IDC. Patients with decreased myocardial b-AR have higher rest-ing adrenergic drive, as reflected by plasma norepinephrine, and may receive greater benefit from being treated by antiadrenergic drugs