If patients feel the symptoms of heart weakness, there are usually several causes as follows: 1. The most common factors are cardiogenic factors, such as coronary atherosclerotic heart disease, unstable angina, arrhythmia, or acute myocarditis, pericarditis, endocarditis, heart valve disease, or even hypertrophic obstructive cardiomyopathy, resulting in transient ischemia, stenosis, and spasm of the coronary arteries, causing insufficient blood supply to the heart muscle. 2. Respiratory diseases such as chronic bronchitis, chronic bronchial dilatation, chronic emphysema, pulmonary heart disease and even pulmonary hypertension can also cause the heart to have symptoms of weakness due to respiratory insufficiency. 3. In some endocrine metabolic diseases such as hypothyroidism or anemia, extreme malnutrition and severe infections can cause an increased load on the heart and lead to heart strain.