The aim of the study is to evaluate the accuracy and reproducibility of the left atrium (LA) anatomy and function in different populations and in patients with atrial fibrillation who have undergone cryoballoon ablation.

This study implies three parts. The first part of the study aims to evaluate the variability and reproducibility of rest two - and three-dimensional echocardiography for the left atrium anatomy and function and to assess their correlation with clinical variables.

The second part of the study aims to evaluate the accuracy and reproducibility of the left atrium anatomy and function using echocardiography and to validate it with cardiac CT. Moreover, the study aims to evaluate which parameters can predict the recurrence of atrial fibrillation in patients who have undergone atrial fibrillation ablation.

The third part of the study aims to assess the accuracy and variability of echocardiographic measurements compared to cardiac magnetic resonance and to find predictors of recurrence after cryoballoon ablation for atrial fibrillation.

Inclusion Criteria:

• subsequent group of patients sent to the echocardiography laboratory for any indication/patients who have undergone a cryoballoon ablation
• older than 18 years old

Exclusion Criteria:

• inadequate image quality during echocardiography, contraindications for computed tomography or cardiac magnetic resonance