Benign slow paroxysmal atrial tachycardia.

Review of 203 24-h ambulatory electrocardiographic tapes of 140 patients disclosed 32 patients with 66 episodes of paroxysmal atrial tachycardia. In contrast to classic sustained paroxysmal supraventricular tachycardia, these episodes were relatively slow and brief. The median duration was 7 beats and the mean 116 beats/min. All episodes were asymptomatic except for three prolonged paroxysms that produced mild palpitation. Sixty-eight percent (45/66) of these episodes occurred during sleep or sinus bradycardia. This was the most common paroxysmal supraventricular arrhythmia observed, and it occurred in patients with a wide variety of cardiac diagnoses. The majority of these episodes appear to arise from an atrial ectopic origin. We conclude that these brief slow atrial paroxysms represent a benign arrhythmia. This rhythm disturbance is present in as many as one quarter of cardiac patients undergoing ambulatory electrocardiographic monitoring. It should not be confused clinically with classic sustained paroxysmal supraventricular tachycardia.