The unbearable futility of deriving the left atrial size from a single-linear dimension

The assessment of the left atrial (LA) size is important, since LA enlargement has been established as a robust predictor of major adverse cardiovascular outcomes,1 including atrial fibrillation (AF).2,3 In addition, the LA size predicts cardiovascular events in patients with lone AF, likelihood of post-operative AF, and success of cardioversion or AF ablation.4 Therefore, current guidelines on the management of patients with AF recommend the assessment of the LA size and function by standard two-dimensional and Doppler echocardiography in the clinical work-up of all patients with AF.5Different imaging modalities are available to assess the LA size.6 However, among all cardiovascular imaging modalities, echocardiography is the most frequently used technique to measure LA volumes and phasic functions.7 Not only echocardiography is widely available, cheap, and harmless for both patients and healthcare professionals, but also has a higher temporal resolution than cardiac magnetic resonance (CMR) or multidetector computed tomography (MDCT).Traditionally, the LA size has been estimated with echocardiography by measuring its anterior–posterior linear dimension, either from M-mode tracings or two-dimensional images. Despite the fact that this measurement is simple to obtain and has been extensively used in clinical routine and research work, it is now clear that LA anterior–posterior diameter is not representative of the true LA size since the LA has an asymmetric three-dimensional shape. Inaccuracy of the anterior–posterior linear dimension …