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Left atrial volume

The left atrial volume is commonly measured by echocardiographyormagnetic resonance tomography. It is calculated from biplane recordings with the equation:

${\displaystyle {A}_{L}={\frac {8}{3\pi }}{\frac {A4c\cdot A2c}{L}}}$

where A4c and A2c denote LA areas in 4- and 2-chamber views respectively, and L corresponds to the shortest long-axis length measured in either views.^[1]

Usually, the volume of the left atrium is divided by the body surface area in order to provide an extensive property, which is independent from body size.^[2][3] The resulting index is referred to as left atrial volume index (LAVI):

${\displaystyle LAVI={\frac {{A}_{L}}{BSA}}}$

LAVI between 16 and 34 ml/m2 is regarded as normal. 2015 ASE guidelines.

Enlargement of the left atrium is a form of cardiomegaly. Moderately increased LAVI (63 to 73 mL/m²) is associated with slightly elevated mortality hazard and severely increased LAVI (>73 mL/m²) with significantly higher hazard ratio of mortality.^[2]

LAVI predicts survival after acute myocardial infarction,^[4] postoperative atrial fibrillation in subjects undergoing heart surgery,^[5] atrial fibrillation and stroke^[6] as well as hospital admission in ambulatory patients.^[7]