Interatrial block (IAB) refers to conduction disorders located between the right and the left atrium, and it was found to be a substrate for the development of atrial fibrillation (AF). The pathophysiology of IAB is directly related to a block in the Bachmann’s bundle area. IAB has a prevalence of 1‰ in the global population of middle age people, and 2% among patients with valvular heart disease and cardiomyopathies. IAB was found to be an independent predictor of AF in different clinical entities (1-6). It was demonstrated that advanced IAB was strongly associated with a higher risk of AF recurrence one year following pharmacological cardioversion; independent of the antiarrhythmic drug utilized (3). In addition, the presence of pre-existent advanced IAB was associated with a higher risk of AF recurrence post catheter ablation for paroxysmal AF (7), and also related to prediction of new-onset AF after successful cavo-tricuspid isthmus ablation in patients with typical atrial flutter and no history of AF (8).