An ectopic atrial rhythm is a rhythm where an ectopic atrial focus functions as the main pacemaker of the heart temporarily. The rate set by this ectopic pacemaker must be below 100 beats per minute (BPM), and the PR interval is within the normal range or slightly prolonged. The QRS interval and morphology should be identical to that found in normal sinus rhythm, unless some aberrancy in the conduction of the impulse through the atrioventricular (AV) node or ventricles is encountered, there is an electrolyte abnormality present, or there is a preexisting bundle branch block.
Usually, ectopic atrial rhythms are hemodynamically insignificant because the rates are within the normal range. The atria contract fairly well and the PR interval is normal or slightly prolonged, as mentioned above. These factors allow the ventricles to have some overfill, and the sequence of systole and diastole is kept within acceptable limits.
The rhythm can be found in patients with or without significant structural heart disease and is usually transient. Recurrences are possible and are commonly found. In general, ectopic atrial rhythm is commonly found in patients on routine Holter monitoring. Treatment should be based on symptoms and on the hemodynamic status of the patient. As usual, even though this rhythm is usually benign, these patients should be referred for further evaluation.