Sudden death is possible with heart failure and a cardiac ejection fraction of 30%. It is mainly due to a decrease in ejection fraction or the presence of severe malignant arrhythmia. Patients with heart failure, decreased cardiac contractility, abnormal blood circulation conditions, a significant decrease in ejection fraction, such as a sudden aggravation of the condition, heart failure loss of compensation, cardiogenic shock, can easily lead to insufficient blood supply to the myocardium as well as insufficient cerebral blood supply. Severe malignant arrhythmias, such as ventricular tachycardia and ventricular fibrillation, may occur with a heart failure fraction of 30%, which may cause sudden termination of cardiac pumping and sudden death. Resuscitative measures such as external cardiac compression and electrical defibrillation are required. May receive medications or ICD placement to prevent episodes of malignant arrhythmia. The presence of heart failure with ejection fraction of 30% suggests that the physical condition is obviously abnormal, and should be promptly admitted to the hospital for medical treatment and standardized treatment under the guidance of clinicians to avoid life-threatening situations.