Premature atrial contraction

Premature atrial contractions (PACs), also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common cardiac dysrhythmia characterized by premature heartbeats originating in the atria. While the sinoatrial node typically regulates the heartbeat during normal sinus rhythm, PACs occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat.[1] The exact cause of PACs is unclear; while several predisposing conditions exist, PACs commonly occur in healthy young and elderly people. Elderly people that get PACs usually don't need any further attention besides follow ups due to unclear evidence.[2][3] PACs are often completely asymptomatic and may be noted only with Holter monitoring, but occasionally they can be perceived as a skipped beat or a jolt in the chest. In most cases, no treatment other than reassurance is needed for PACs, although medications such as beta blockers can reduce the frequency of symptomatic PACs.[4]

Premature atrial contraction
Other namesSupraventricular extra systole (SVES)
Two PACs as seen on a rhythm strip

Risk factors

Hypertension, or abnormally high blood pressure, often signifies an elevated level of both psychological and physiological stress. Often, hypertension goes hand in hand with various atrial fibrillations including premature atrial contractions (PACs).[5] Additional factors that may contribute to spontaneous premature atrial contractions could be:[4]

  • Increased age
  • Abnormal body height
  • History of cardiovascular disease (CV)
  • Abnormal ANP levels
  • Elevated cholesterol


Premature atrial contractions are typically diagnosed with an electrocardiogram, Holter monitor, or cardiac event monitor.


On an electrocardiogram (ECG), PACs are characterized by an abnormally shaped P wave. Since the premature beat initiates outside the sinoatrial node, the associated P wave appears different from those seen in normal sinus rhythm. Typically, the atrial impulse propagates normally through the atrioventricular node and into the cardiac ventricles, resulting in a normal, narrow QRS complex. However, if the atrial beat is premature enough, it may reach the atrioventricular node during its refractory period, in which case it will not be conducted to the ventricle and there will be no QRS complex following the P wave.


Premature atrial contractions are often benign, requiring no treatment. Occasionally, the patient having the PAC will find these symptoms bothersome, in which case the doctor may treat the PACs. Sometimes the PACs can indicate heart disease or an increased risk for other cardiac arrhythmias. In this case the underlying cause is treated. Often a beta blocker will be prescribed for symptomatic PACs.[6]


In otherwise healthy patients, occasional premature atrial contractions are a common and normal finding and do not indicate any particular health risk. Rarely, in patients with other underlying structural heart problems, PACs can trigger a more serious arrhythmia such as atrial flutter or atrial fibrillation.[7] In otherwise healthy people, PACs usually disappear with adolescence.

Supraventricular extrasystole

A supraventricular extrasystole (SVES) is an extrasystole or premature electrical impulse in the heart, generated above the level of the ventricle. This can be either a premature atrial contraction or a premature impulse from the atrioventricular node. SVES should be viewed in contrast to a premature ventricular contraction which has a ventricular origin and the associated QRS change. Instead of the electrical impulse beginning in the sinoatrial (SA) node and propagating to the atrioventricular (AV) node, the signal is conducted both to the ventricle and back to the SA node where the signal began.[8]

See also


  1. , Nickolls, Peter; Richard M. T. Lu & Kenneth A. Collins, "Apparatus and method for antitachycardia pacing using a virtual electrode"
  2. Brodsky M, Wu D, Denes P, Kanakis C, Rosen KM (March 1977). "Arrhythmias documented by 24 hour continuous electrocardiographic monitoring in 50 male medical students without apparent heart disease". Am. J. Cardiol. 39 (3): 390–5. doi:10.1016/S0002-9149(77)80094-5. PMID 65912.
  3. Folarin VA, Fitzsimmons PJ, Kruyer WB (September 2001). "Holter monitor findings in asymptomatic male military aviators without structural heart disease". Aviat Space Environ Med. 72 (9): 836–8. PMID 11565820.
  4. Lin, Chin-Yu; Lin, Yenn-Jiang; Chen, Yun-Yu; Chang, Shih-Lin; Lo, Li-Wei; Chao, Tze-Fan; Chung, Fa-Po; Hu, Yu-Feng; Chong, Eric (2015-08-27). "Prognostic Significance of Premature Atrial Complexes Burden in Prediction of Long-Term Outcome". Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease. 4 (9): e002192. doi:10.1161/JAHA.115.002192. ISSN 2047-9980. PMC 4599506. PMID 26316525.
  5. Healy, Jeff (2003). "Atrial fibrillation: hypertension as a causative agent, risk factor for complications, and potential therapeutic target". The American Journal of Cardiology. 91 (10): 9–14. doi:10.1016/S0002-9149(03)00227-3.
  6. Hueston, Kesh A. Hebbar|William J. (2002-06-15). "Management of Common Arrhythmias: Part I. Supraventricular Arrhythmias - American Family Physician". American Family Physician. 65 (12): 2479–86. PMID 12086237. Retrieved 2017-03-29.
  7. Jensen, Thomas J.; Haarbo, Jens; Pehrson, Steen M.; Thomsen, Bloch (2004-04-01). "Impact of premature atrial contractions in atrial fibrillation". Pacing and Clinical Electrophysiology: PACE. 27 (4): 447–452. doi:10.1111/j.1540-8159.2004.00462.x. ISSN 0147-8389. PMID 15078396.
  8. Ernst., Mutschler (1995-01-01). Drug actions : basic principles and theraputic aspects. Medpharm Scientific Publishers. ISBN 978-0849377747. OCLC 28854659.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.