Left atrial enlargement

Left atrial enlargement (LAE) or left atrial dilation refers to enlargement of the left atrium (LA) of the heart, and is a form of cardiomegaly.

Left atrial enlargement
Other namesLeft atrial dilation
SpecialtyCardiology

Signs and symptoms

Left atrial enlargement can be mild, moderate or severe depending on the extent of the underlying condition. Although other factors may contribute, left atrium size has been found to be a predictor of mortality due to both cardiovascular issues as well as all-cause mortality. Research suggests that left atrium size as measured by an echo-cardiograph may be linked to cardiovascular disease. However, studies that have found LAE to be a predictor for mortality recognize the need for more standardized left atrium measurements than those found in an echo-cardiogram.[1]

Causes

In the general population, obesity appears to be the most important risk factor for LAE.[2] LAE has been found to be correlated to body size, independent of obesity, meaning that LAE is more common in people with a naturally large body size.[1] Also, a study found that LAE can occur as a consequence of atrial fibrillation (AF),[3] although another study found that AF by itself does not cause LAE. The latter study also showed that the persistent type of AF was associated with LAE, but the number of years that a subject had AF was not.[4]

Obstructive sleep apnea (OSA) may be a cause of LAE in some cases. When an OSA event occurs, an attempt is made to breathe with an obstructed airway and the pressure inside the chest is suddenly lowered. The negative intrathoracic pressure may cause the left atrium to expand and stretch its walls during each OSA event. Over time, the repetitive stretching of the left atrium may result in a persistent left atrial enlargement.[5]

Diagnosis
Left atrium size[6] Women Men
normalenlargednormalenlarged
mildmoderateseveremildmoderatesevere
Diameter  (mm) 27–3839–4243–46≥4730–4041–4647–52≥52
Volume  (ml) 22–5253–6263–72≥7318–5859–6869–78≥79
Volume/BSA  (ml/m²)   16–2829–3334–39≥4016–2829–3334–39≥40
   BSA, body surface area
ECG of V1 showing the large negative of the P wave indicating left atrial enlargement[7]

LAE is suggested by an electrocardiogram (ECG) that has a pronounced notch in the P wave.[8] However, if atrial fibrillation is present, a P wave would not be present.[9] In any case, LAE can be diagnosed and measured using an echocardiogram (ECHO).

Characterizing the size of the left atrium according to its volume is preferred over a single linear dimension since enlargement can be different for different directions. For example, because of the smaller distance in the thoracic cavity between the sternum and spine, compared to the other directions, less room exists for enlargement of the left atrium along the anteroposterior axis.[6] By approximating the shape of the left atrium as an ellipsoid, its volume can be calculated from measurements of its dimensions along three perpendicular directions.[3]

Indexing the left atrial volume to body surface area (volume/BSA) is recommended by the American Society of Echocardiography and the European Association of Echocardiography. The values for volume/BSA in the following table are the best validated, and are the same for both men and women.[6]

References
  1. Patel DA, Lavie CJ, Milani RV, Shah S, Giliand Y (Winter 2009). "Clinical Implications of Left Atrial Enlargement: A Review". The Ochsner Journal. 9 (4): 191–196. PMC 3096293. PMID 21603443.
  2. Stritzke J, Markus MR, Duderstadt S, Lieb W, Luchner A, Döring A, Keil U, Hense H, Schunkert H (2009-11-17). "The Aging Process of the Heart: Obesity Is the Main Risk Factor for Left Atrial Enlargement During Aging: The MONICA/KORA (Monitoring of Trends and Determinations in Cardiovascular Disease/Cooperative Research in the Region of Augsburg) Study". Journal of the American College of Cardiology. 54 (21): 1982–9. doi:10.1016/j.jacc.2009.07.034. PMID 19909880. Retrieved 2009-12-02.
  3. Sanfilippo AJ, Abascal VM, Sheehan M, Oertel LB, Harrigan P, Hughes RA, Weyman AE (1990). "Atrial enlargement as a consequence of atrial fibrillation A prospective echocardiographic study". Circulation. 82 (3): 792–7. doi:10.1161/01.CIR.82.3.792. PMID 2144217. Retrieved 2009-12-02.
  4. Osranek M, Bursi F, Bailey KR, Grossardt BR, Brown RD Jr, Kopecky SL, Tsang TS, Seward JB (Dec 2005). "Left atrial volume predicts cardiovascular events in patients originally diagnosed with lone atrial fibrillation: three-decade follow-up". European Heart Journal. 26 (23): 2556–61. doi:10.1093/eurheartj/ehi483. PMID 16141257. Archived from the original on 2013-04-15. Retrieved 2009-12-27. See p. 2560 Left ventricular filling pressure, LAV, and AF.
  5. Latina JM, Estes III NAM, Garlitski AC (2013). "The Relationship between Obstructive Sleep Apnea and Atrial Fibrillation: A Complex Interplay". Pulmonary Medicine. 2013 (621736): 1–11. doi:10.1155/2013/621736. PMC 3600315. PMID 23533751. See section 5.1.
  6. Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA, Picard MH, Roman MJ, Seward J, Shanewise J, Solomon S, Spencer KT, St John Sutton M, Stewart W (March 2006). "Recommendations for chamber quantification". European Journal of Echocardiography. 7 (2): 79–108. doi:10.1016/j.euje.2005.12.014. PMID 16458610. Retrieved 2012-08-26.
  7. Edhouse, J; Thakur, RK; Khalil, JM (25 May 2002). "ABC of clinical electrocardiography. Conditions affecting the left side of the heart". BMJ (Clinical research ed.). 324 (7348): 1264–7. doi:10.1136/bmj.324.7348.1264. PMC 1123219. PMID 12028984.
  8. Edhouse J, Thakur RK, Khalil JM (2002-05-25). "ABC of clinical electrocardiography. Conditions affecting the left side of the heart". British Medical Journal. 324 (7348): 1264–7. doi:10.1136/bmj.324.7348.1264. PMC 1123219. PMID 12028984.
  9. "Atrial Fibrillation (for Professionals)". American Heart Association, Inc. 2008-12-04. Archived from the original on 2009-03-28.
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