A method and apparatus for monitoring a patient's cardiac electrical activity is disclosed. The method includes determining a characteristic of the cardiac signals during a detected episode of atrial fibrillation. The method further includes comparing the characteristic to an atrial fibrillation therapy threshold and if the characteristic is less than or equal to the atrial fibrillation therapy threshold further comparing the characteristic to a self-termination threshold. If the characteristic is less than the self-termination threshold the method withholds anti-tachycardia therapy to allow the arrhythmia to self-terminate.