Although studies conducted in transgenic mice have demonstrated that the β1-Arg389 variant predisposes to a depressed ventricular function and pathological fibrosis,14 several studies relating the Gly389Arg polymorphism of the β1-AR gene with the risk for human heart failure or IDC and the progression of these diseases have produced inconsistent data.14,16-20. This evidence concerns the gene ADRB1 and heart failure.