 The study is a randomized controlled trial. Patients randomly enter into two treatment groups: 1the Carvedilol group and 2the Propranolol group. Treatment allocation is by block randomization, with an equal number for Carvedilol and Propranolol. The results are concealed in opaque envelopes. The dose of non-selective β-blockerNSBB is titrated according to systolic arterial blood pressure ABPsys and heart rate HR. Doses are increased every 2-3 days until ABPsys is not less than 90 mm Hg and HR is not less than 55 bpm. Carvedilol is started at a dose of 6.25mgd, and titrated to a maximum dose of 25mgd. Patients receiving propranolol start at a dose of 30 mgday and the dose will be increased to a maximum dose of 160 mgday. Patients will be followed up with telephone calls every 2 months. After taking these 2 drugs for 6 months, patients come for clinic visits, receiving laboratory tests and endoscopic examinations, and events of primary and secondary outcomes will be analyzed. 