Fasting is required to do tests such as blood draws for heart failure. The main blood tests that need to be done in heart failure patients are brain natriuretic peptide tests, aldosterone levels, catecholamines, thyroid function, kidney function, electrolytes, cardiac enzymology tests such as creatine kinase, troponin, and coagulation. Most of these tests do not require fasting. Patients with heart failure routinely also need to check liver function, lipids, blood glucose, etc. These tests are recommended to be performed on an empty stomach for more accurate results. Therefore, if the same blood collection is done, it is recommended to do it on an empty stomach. In addition to the above blood tests, heart failure patients also need a cardiac ultrasound. Through cardiac ultrasound, the patient’s heart function is evaluated, and the common index is ejection fraction. Ejection fraction refers to the efficiency of the heart in storing blood and pumping out blood. If the ejection fraction is too low, the patient will experience heart failure and may develop the pathology of heart failure. What tests are required for patients with heart failure varies from condition to condition and needs to be based on diagnostic needs, judgment made by the doctor and under the doctor’s supervision.