Atrial Premature Beats
Atrial premature beats (APBs or PACs) generally fall into two broad categories: benign atrial premature beats and pathological atrial premature beats. Benign APBs are quite common and may actually occur from time to time in most people, although they can occur with great frequency in some people (even every other beat for extended periods of time). They are particularly common in infants and teenagers. They tend to occur at lower heart rates, and tend to be abolished when the heart rate increases, as with exercise. On an ECG, benign APBs generally all have the same appearance (morphology), and one does not see them in conjunction with more serious arrhythmias (such as atrial tachycardia). Benign APBs are of no importance, and do not require treatment unless they cause symptoms (palpitations).
Pathological APBs are very rare, but can be a sign of injury or inflammation of the heart muscle. They are particularly uncommon in children. They tend to be worse with exercise and at higher heart rates, take multiple forms (polymorphic or multifocal) on an ECG or Holter recording and may be associated with more serious arrhythmias.
Telling the two types of APBs apart usually requires an ECG or a more prolonged monitoring procedure, such as a Holter monitor, a physical examination, evaluation of the family history, and perhaps other tests depending on the particular circumstances and preference of the physician. I tend to be more concerned about a child who 1) has an irregular rhythm all, or most, of the time; 2) has shortness or breath, dizziness or fainting during an arrhythmia, or an unexpected fainting episode or seizure; 3) who is not growing well; or 4) has a family history of serious arrhythmias or heart problems in young people. When any of these conditions are true, I recommend a child be evaluated by a pediatric cardiologist, or, if none are available, an adult cardiologist.