When the "lifeline" on the dynamic electrocardiogram monitor suddenly changes to a straight line, it means that the patient is in danger of life. Sudden cardiac arrest or loss of effective blood pumping ability often leads to loss of consciousness and systemic organ failure. If appropriate medical intervention is not immediately received, death can usually occur within a few minutes, with a mortality rate of over 90%. And this is what we often call sudden cardiac death. So, can early warning symptoms be used to predict impending cardiac arrest and avoid sudden death? Over the past decade, this issue has received increasing attention. In the past, a Japanese study reported collecting symptom information from 1042 people and observed that among 644 people with any premonitory symptoms, the three most common symptoms were difficulty breathing (28%), chest pain (21%), and syncope (13%). A recent study in The Lancet Digital Health also revealed some signs before cardiac arrest. About half of patients with cardiac arrest will have some symptoms hours, days or weeks before cardiac arrest. These "signs" can be used to predict and prevent cardiac arrest, thus reducing incidence rate and mortality. Researchers found 848 participants aged 18 to 85 from California, USA between February 2015 and January 2021, all of whom had experienced symptoms of cardiac arrest. In early studies, it was found that patients with cardiac arrest were more likely to experience symptoms such as chest pain, breathing difficulties, dizziness, palpitations, and syncope, but early studies were limited by the lack of a control group. The researchers also identified 1171 patients as a control group. Research has found significant differences in symptom frequency and patterns among different genders. For women, the most obvious symptom of impending cardiac arrest is shortness of breath, while men are more likely to experience chest pain, difficulty breathing, sweating, and epilepsy. Research also shows that if corresponding symptoms occur, immediately call the emergency phone for emergency medical assistance. People who call the rescue phone before falling down have a survival rate of more than five times higher for cardiac arrest. Based on this study, let's summarize the possible symptoms before cardiac arrest. If you are already in a high-risk group or have cardiovascular disease, you should pay more attention to these six symptoms: 1. difficulty breathing, 2. chest pain, 3. syncope, 4. dizziness, 5. palpitations, and 6. sweating (especially for men). So, how to protect the heart in daily life? There are three types of suggestions: 1. Change your lifestyle and eat a healthy diet: a high fiber, low fat, and low salt diet can help reduce the risk of heart disease. Regular exercise: Taking appropriate physical exercise according to one's physical condition can improve heart health. Smoking cessation and alcohol restriction: Avoid smoking and excessive alcohol consumption, both of which are related to heart problems. Weight management: Being overweight or obese increases the risk of heart disease, and efforts should be made to maintain a healthy weight. 2. Regular examination and medication blood pressure monitoring: Hypertension is an important risk factor for heart disease and should be regularly checked. Blood lipid test: High cholesterol is also a risk factor, which can be achieved through medication and