- Acute HF expressed by acute dyspnea New York Heart Association (NYHA) class III or IV, and a BNP-level ≥ 500 pg/ml. The diagnosis of acute HF is additionally based on typical symptoms and clinical findings, supported by appropriate investigations such as ECG, chest X-ray, and Doppler-echocardiography as recommended by current ESC guidelines on the diagnosis and treatment of acute HF