Introduction: Heart failure is the endpoint of all heart disease. Marked by an oscillating evolution, with pe-riods of aggravation and remission, it is one of the main public health problems worldwide, both throu-gh implications on morbidity and mortality as well as the debilitating effects on quality of life. Despite recent advances, both through the development of implanta-ble devices and the addition of neprylisine-inhibitors to drug therapy, management of the patient with heart failure remains a therapeutic challenge.

Methods: We present the case of a 68-year-old female admitted to our service for heart failure symptoms, with a known history of coronary artery disease with global cardiac dilatation and recently cardiac resynchroniza-tion therapy (CRT). At the presentation, the patient was conscious, hemodynamically stable. Paraclinical investigations revealed the occurrence of atrial fibrilla-tion with rapid ventricular conduction, in the context of biatrial dilatation. Given these facts, the CRT device was switched to mode VVI biventricular stimulation, losing the benefit of atrial contraction and subsequent worsening of symptoms. In this context, the question of the appropriate therapeutic decision regarding the restoration of sinus rhythm has been raised.

Results: We appreciated that, despite the biatrial dilati-on with a relatively high probability of atrial fibrillation recurrence, the benefit of restoring sinus rhythm was undeniable. Oral anticoagulation with a direct antico-agulant was initiated followed by antiarrhythmic treat-ment with amiodarone. At one month’s re-evaluation, the persistence of atrial fibrillation was observed, and electrical conversion was achieved, with the mainte-nance of sinus rhythm at subsequent re-evaluations and a significant improvement in symptomatology.

Conclusions: According to the guidelines of the Eu-ropean Society of Cardiology for the management and treatment of heart failure, CRT finds its maximum be-nefit in patients in sinus rhythm. Often, the inception of atrial fibrillation leads to exacerbation of heart failu-re symptoms, and in the case of a patient with CRT it leads to a significant decrease in therapeutic benefits. In this context and taking into account the young age of the patient, avoiding the permanent atrial fibrillation was the right decision. The increasing of antiarrhyth-mic doses facilitated the maintenance of sinus rhythm and implicitly the maximum therapeutic benefit throu-gh CRT.