Abstract A 62–year–old man was admitted to our emergency department for worsening nocturnal dyspnea and orthopnea for 15 days. Finding of Acute Pulmonary Edema in a setting of non datable high ventricular response atrial fibrillation (AF) associated with severe LV dysfunction. NT–proBNP 8.252 pg/ml. ECG: atrial fibrillation with high ventricular response (120/bpm). TTE: Severe left ventricular systolic disfunction (EF 20%). TOE/3D TOE: evidence of voluminous oval–shaped thrombotic formation (10 x 17 mm) protruding in LA and completely occluding the left atrial appendage (LAA). LA thrombosis in patients with AF is relatively rare and represents a contraindication to rhythm control strategies. Once an LAA thrombus is identified, effective anticoagulation is recommended for at least three weeks or until LAA thrombus resolution is detected. Available evidence on left atrial thrombus dissolution largely refers to the use of vitamin K antagonist oral anticoagulant (VKAs), but their effectiveness may be influenced by variability in the level of anticoagulant activity obtained, wich may be suboptimal. In a recent prospective observational study has been evaluated the effectiveness of Edoxaban for the resolution of LA thrombosis in 25 patients with AF: it has been demonstrated a complete thrombus resolution in 56% of patients at 4 weeks, similar to studies using VKAs and the other NOACs. Use of NOACs in this setting represents a great field of interest for the near future. In our experience, indeed, after confirmed diagnosis of LAA thrombus, we started anticoagulant therapy with warfarin (currently the first choice), however due to poor INR control, we switched to continuous infusion of unfractionated heparin (UFH), wich represents, in a hospital setting, a safe and effective method for thrombus dissolution, allowing continuous monitoring of efficacy and a rapid cessation of effect in case of major bleeding. In this way we obtained complete thrombus dissolution in about 3 weeks. At the meantime we initiate a rate control therapy, an optimized treatment for HFrEF and intravenous diuretics. Our experience highlights the need of great ductility in the choice of anticoagulant therapy in patients with evidence of voluminous LAA thrombus, monitoring treatment’s efficacy parameters and being ready to change strategy if necessary and it reminds that auricular thrombosis is often inserted in a wider picture of heart disease wich requires multiple other specifics treatments.