Myocardial beta-adrenergic receptor density assessed by 11C-CGP12177 PET predicts improvement of cardiac function after carvedilol treatment in patients with idiopathic dilated cardiomyopathy.

We evaluated whether myocardial P-adrenergic receptor (beta-AR) density, as determined by (11)C-CGP12177 PET, could predict improvement of cardiac function by P-blocker carvedilol treatment in patients with idiopathic dilated cardiomyopathy (IDC). Methods: Ten patients with IDC (left ventricular ejection fraction [LVEF] < 45%) were studied. Myocardial PAR density was estimated using (11)C-CGP12177 PET before treatment with carvedilol. Changes of LVEF in response to dobutamine infusion (ALVEF-dobutamine) were also measured by echocardiography. Changes of LVEF (Delta LVEF-carvedilol) were evaluated after 20 mo of carvedilol treatment. Results: Baseline myocardial PAR density significantly correlated with Delta LVEF-carvedilol (r = -0.88, P < 0.001). In contrast, Delta LVEF-clobutamine did not correlate with Delta LVEF-carvedilol (P = 0.65). Myocardial PAR density was the significant multivariate independent predictor of Delta LVEF-carvedilol (p = -0.88, P < 0.001) among univariate predictors, including functional class (r = 0.76, P < 0.05), plasma norepinephrine (r = 0.85, P < 0.01), LVEF (r = -0.64, P < 0.05), and age as confounding factors. Furthermore, myocardial PAR density was significantly correlated with plasma norepinephrine (r = -0.79, P < 0.01) and LVEF (r = 0.70, P < 0.05). Conclusion: Myocardial PAR density is more tightly related to improvement of LVEF-carvedilol than is cardiac contractile reserve in patients with IDC. Patients with decreased myocardial PAR have higher resting adrenergic drive, as reflected by plasma norepinephrine, and may receive greater benefit from being treated by antiadrenergic drugs.