ABSTRACT
Atrial fibrillation is the most prevalent arrhythmia in clinical practice and has different strategies for its control. Of these strategies, the percutaneous ablation of the pulmonary veins stands out, with robust results in relation to drug treatment. It is an invasive procedure and, therefore, not free from complications, which must be properly diagnosed and treated. Among the possible complications, there is stiff atrium syndrome, characterized by reduced atrial compliance caused by post-ablation fibrosis, which, in turn, leads to atrial filling dysfunction and the consequent increase in atrial and venous capillary pulmonary pressures. The case report demonstrates this infrequent but important complication, which presents good results for clinical treatment, in addition to the contribution of cardiac magnetic resonance in its diagnosis and in the assessment of arrhythmia recurrence rates.