Results showed that long _ cycle leading to atrial fibrillation and flutter were mostly compensating period due to atrial premature beat or obviously sinus bradycardia.

In them, sinus tachycardia, myocardial ischemia, atrial and ventricular premature beat were common.

Conclusion: atrial overdrive can prevent AF, which may results from accelerating interatrial conduction, inhibiting atrial premature beat, eliminating sinus bradycardia and long short interval.