Objective To evaluate the efficacy and safety of long-term treatment with arotinolol in patients with idiopathic dilated cardiomyopathy（IDCM）.Methods Sixty-three patients with IDCM were evaluated at baseline and after 12-month therapy with arotinolol.The conventional therapy for congestive heart failure was continued throughout the study with arotinolol as the only β-blocker.Left ventricular function was assessed with the New York Heart Association functional class and two-dimensional echocardiography.Results After 12-month arotinolol treatment

there was a significant improvement in left ventricular systolic function.Left ventricular end-systolic dimension significantly decreased from 59.52±8.83 mm to 50.89±8.17 mm（P<0.001）.Left ventricular ejection fraction significantly increased from 27.39%±7.94% to 41.13%±9.45%（P<0.001）.Left ventricular mass index decreased from 150.47±42.42 g/m2 to 141.58±34.36 g/m2（P<0.01）.No adverse events leading to premature discontinuation of study drug occurred.Conclusion In this preliminary study

12-month arotinolol treatment has a favorable effect on left ventricular function in patients with IDCM

and it is safe and well tolerated.