ADRB1 and heart failure: Given the reported associations between the β1 AR-Arg389 polymorphism and the response to β-blocker treatment with heart failure [9], the much higher norepinephrine affinity and adrenergic signal transduction capacity of Arg389 β1-AR may protect patients from excessive sympatholysis [27] that has been associated with increased mortality in β1 389-Gly carriers receiving bucindolol [28].