Which method is appropriate for measuring the left atrial diameter in parasternal long axis?

Comprehensive and Detailed Explanation From Exact Extract:

The recommended method to measure left atrial diameter in the parasternal long axis view is the inner edge to inner edge technique, perpendicular to the aortic root, measured at end-diastole. This approach provides the most reproducible and standardized measurement.

Measurement parallel to the aortic root or at end-systole is less accurate. Outer edge measurements overestimate size.

ASE chamber quantification guidelines specify this method for standardization and reproducibility in adult echocardiography practice【12:ASE Chamber Quantification Guidelines†p.90-95】【16:Textbook of Clinical Echocardiography, 6e†p.120-125】.