If patients often have inexplicable panic attacks, the following factors should be taken into consideration: 1. Patients with endocrine metabolic diseases, such as hyperthyroidism and hyperadrenocorticism, will have inexplicable panic attacks, palpitations, precordial discomfort, accompanied by peripheral weakness and other clinical symptoms. 2. Patients with other endocrine diseases, such as diabetes mellitus, will also have inexplicable panic attacks when they have hypoglycemic reactions. 3. Patients with coronary artery disease will also have inexplicable panic attacks if they have unstable angina or other diseases of cardiac origin, such as myocarditis, pericarditis, heart valve disease, rheumatic heart disease. 4. For some patients with cardiac neurosis, they will also have inexplicable panic attacks and palpitations when their vegetative nerve function is disturbed.