This study seeks to define a beta-adrenergic receptor kinase molecule in the blood and its role as an improved biomarker to be used for the diagnosis, assessment and management of patients with heart failure. We will test blood cell samples for the levels of this molecule, called "G protein-coupled receptor kinase-2" (GRK2) using both the existing method of GRK2 quantification in the Koch laboratory and using a prototype enzyme immunoassay (EIA) method being developed by Johnson \& Johnson, Ortho-Clinical Diagnostics (OCD).
