Lone Giant Atrium as a Variant of Atrial Cardiomyopathy: A Cardiovascular Magnetic Resonance Imaging Case Series.

Advances in cardiovascular imaging have expanded the scope and precision of rare diagnoses. Handling a patient with a giant left atrium, we focused on the existence and associated factors of "lone giant (left or right) atria" in our clinical setting. The aim of the current study was to establish reasonable cut-off values for the diagnosis of "giant atrium". Our analysis utilised echocardiography and cardiovascular magnetic resonance (CMR) imaging databases, with the original data re-assessed to ensure consistency and comparability. Four patients met the search criteria, with two cases requiring CMR to confirm the diagnosis of "giant atrium", correcting the initial echocardiographic assessment. Both echocardiography and CMR excel in the assessment of atrial anatomy, although the superior image quality and multiplanar capabilities of CMR support its preference. In assessing the atrial size, the use of 3D volumetric measurements should replace traditional biplane methods due to the complex anatomy of the atrium. We propose the use of an indexed volume threshold (>120 mL/m²) rather than simple diameter measurements for the diagnosis of "giant atria". Structural atrial abnormalities appear to correlate with an increased risk of atrial arrhythmias, while potential serious complications such as thromboembolism or compression symptoms require further observation in larger patient cohorts to establish definitive risks.