[RESULTS] ( 2 ) Incidence of Sinus bradycardia , sinus tachycardia , sinus arrest , atrial premature beats , ventricular premature beats , paroxysmal atrial tachycardia , paroxysmal ventricular tachycardia , atrial fibrillation , II-III degree atrioventricular block , ST-T segment changes were reduced from 57.4 % , 44.4 % , 7.4 % , 20.4 % , 13.0 % , 36.5 % , 12.0 % , 8.3 % , 37.0 % , 53.7 % to 4.6 % , 1.9 % ,0.0 % , 3.7 % , 2.8 % , 7.0 % , 0.9 % , 0.0 % , 1.9 % , 4.6 % ( all P < 0.05 ) and the total number of arrhythmias happened at night were significantly lower ( all P < 0.05 ) while the heart rate variability ( HRV ) were significantly higher ( P < 0.01 ) in NPPV group than in control group ; AHI was positively while LSaO2 was negatively correlated with the total night arrhythmia number ( P < 0.01 ) .