Sinus bradycardia may cause sudden death. Sinus bradycardia is a sinus rhythm of less than 60 beats/minute. It can be seen in healthy adults such as athletes and the elderly, but also includes pathologic causes such as hyperkalemia, hypothyroidism, application of beta-blockers such as metoprolol, and diseases of the heart itself such as third-degree AV block. Whether sudden death occurs in sinus bradycardia is closely related to the heart rate. If the heart rate is <30 beats/minute and left untreated, the risk of sudden death is high. If the heart rate is >40 beats/min, it is recommended that a temporary pacemaker be implanted under the supervision of a medical professional. If the bradycardia is 50-55 beats/min, this situation is generally safer. In summary, the occurrence of severe sinus bradycardia is the need for timely medical treatment, to avoid delaying the condition.