What Are the Causes of Premature Atrial Contractions?

Patient Presentation
A 6-year-old male came to clinic for a pre-operative surgical evaluation. The boy had attention deficit hyperactivity disorder with marked inattention and some behavioral issues. He had recently been tried on methylphenidate but was currently off the medication because of side effects and had a return appointment with his psychiatrist. He was otherwise well, except for dental caries necessitating oral rehabilitation under general anesthesia. The past medical history showed surgery for pressure equalizing tubes without any problems. The family history was positive for a cousin who had died from an unknown cardiac problem. The review of systems was negative including no palpitations, dyspnea or syncope.

The pertinent physical exam showed heart rate of 96, and a normal blood pressure without a widened pulse pressure between the upper extremities and lower extremities. HEENT revealed rampant caries and scarred tympanic membranes bilaterally. Heart examination found a grade I/IV systolic murmur best at the mid-left sternal border without radiation that changed with position and respiration. There were no bruits or jugulovenous distention and he had normal femoral pulses. He had an irregularly irregular heart beat with each beat pulsating to the extremities. The rest of his examination was normal.

The work-up included a normal chest radiograph and a 12-lead electrocardiogram with a long rhythm strip. The general pediatrician’s reading of the ECG showed normal consistent P and QRS wave morphologies. There was a P wave for every QRS and a QRS for every P wave. There were several premature beats on the rhythm strip that appeared randomly. There did not appear to be any left ventricular hypertrophy. The pediatrician thought this was premature atrial contractions but she did not read many ECGs, and felt that there were frequent premature beats, and because the patient had a concerning family history and possible need for stimulant medication in the future for his attention issues, she contacted a cardiologist. The ECG and rhythm strip were sent to a pediatric cardiologist who confirmed the diagnosis of premature atrial contractions. He felt that the child could undergo surgery without further immediate evaluation, but because of the same concerns the general pediatrician had that a cardiology appointment and Holter monitor would be appropriate in the near future and before stimulant medication was started.

Case Image
Figure 100 – ECG demonstrating premature atrial contractions

A cardiac arrhythmia or dysrhythmia is an abnormality in the cardiac muscle contraction or variation in the normal rhythm. This includes rhythm loss, irregular rhythms or abnormal regular rhythms. Arrhythmias can present in a number of ways including as an incidental finding, palpitations, syncope, sudden cardiac death or near death. The current recommendations by the American Academy of Pediatrics does not recommend routine a ECG before initiating stimulant medication for Attention Deficit Hyperactivity Disorder, but does recommend a targeted family history and physical examination. If there are any concerns, then further evaluation should be obtained before starting medication. Likewise, if stimulant medication is started the history or examination changes then again further evaluation is warranted.

Premature atrial contractions (PACs) are common in neonates and children. The ECG findings show a normal to narrow QRS complex with an incomplete compensatory pause. That means that the total length of two cycles that includes a premature beat is less than 2 regular cycles. Sometimes a PAC is not followed by a QRS complex because the QRS is not conducted. The P waves may have different morphology depending where they are located in the atria; it is upright when the focus is high in the atria and can be inverted when low in the atria.

How frequent is too frequent is hard to discern but one study of adults states that having PACS 100 times/day is frequent. When PACs are frequent, a more extended evaluation is often done (i.e. a Holter or event monitor and echocardiogram) to rule out an underlying structural abnormality or arrthymogenic cause. Frequent PACs in children do not appear to have any hemodynamic consequences, but there are studies in older adults where PACs appear to predict new occurrences of atrial fibrillation and its associated cardiovascular events.

Learning Point
The causes of PACs includes digitalis toxicity, caffeine, theophylline or other stimulant, post-cardiac surgery and during pregnancy. PACs usually cause no hemodynamic problems and generally no treatment is necessary in children. Treatment is for an underlying cause if one is discovered. PACs associated with gestation usually resolve with delivery.

Questions for Further Discussion
1. What other arrhythmias originate in the atria?
2. What are indications for a cardiology evaluation?
3. What are relative contraindications to pre-scheduled general anesthesia?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Arrhythmia

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Perrin JM, Friedman RA, Knilans TK; Black Box Working Group; Section on Cardiology and Cardiac Surgery. Cardiovascular monitoring and stimulant drugs for attention-deficit/hyperactivity disorder. Pediatrics. 2008 Aug;122(2):451-3.

Tanel RE. ECGs in the ED. Pediatr Emerg Care. 2011 Dec;27(12):1203-4.

Chong BH, Pong V, Lam KF, Liu S, Zuo ML, Lau YF, et al. Frequent premature atrial complexes predict new occurrence of atrial fibrillation and adverse cardiovascular events. Europace 2012;14:942-7.

Tschudy MM, Arcara KM. The Harriet Lane Handbook. 19th. Edit. Elsevier/Mosby Publications: Philadelphia, PA. 2012:174-76.

Pickett C, Zimmerman PJ. Evaluation of Palpitations. ePocrates. Available from the Internet at https://online.epocrates.com/u/2912572/Evaluation+of+palpitations/Differential/Etiology (rev. 5/24/2012, cited 9/17/2012).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.

  • Interpersonal and Communication Skills
    19. The health professional works effectively with others as a member or leader of a health care team or other professional group.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.


    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital