Does Size Matter? What’s the Size of Your Left Atrium?
When in A-Fib, your left atrium has to work harder than normal and tends to stretch and dilate over time. Thus, an enlarged heart, specifically your left atrium, can be one symptom of living with Atrial Fibrillation.
Other contributors to an enlarged left atrium are obstructive sleep apnea (OSA) and high blood pressure. Also, people with a naturally large or tall body size often have an enlarged left atrium (ELA).
Consequences of an Enlarged Left Atrium
One study showed that Persistent A-Fib was associated with left atrium size (but not the number of years that a patient had A-Fib).
Left atrium size has been found to be a predictor of mortality due to both cardiovascular issues as well as all-cause mortality (although other factors may contribute).
As a result, some medical centers won’t do a Pulmonary Vein Ablation (Isolation) procedure if the left atrium is enlarged (over 5.5 cm). However, with the newer ablation techniques, other centers will. Surgeons also are reluctant to operate on someone with an enlarged heart.

Normal left atrium: 2.0-4.0 cm
Left Atrium Size: Normal vs Enlarged
An enlarged left atrim can be diagnosed and measured using an echocardiogram (ECHO). A normal left atrium measures around 2.0-4.0 cm (20 mm–40 mm).
Ranges: Left atrial enlargement can be mild, moderate or severe depending on the extent of the underlying condition.
Note: Measurement of the volume is preferred over a single linear dimension since enlargement can be different for different directions.
Why You Need to Know Your Measurement
If you’ve had A-Fib for a while with significant symptoms, we often advise you to ask your doctor for this measurement to see if your left atrium is being enlarged.
Store this info with your other A-Fib test results and other papers in your A-Fib Binder or folder. This will be your benchmark for future comparison.
To rank the size of your atrium, go to TABLE: Indexing the Left Atrial Size