Sinus arrhythmias include sinus tachycardia, sinus bradycardia, sinus arrest, sinus block and sick sinus syndrome. The main danger of sinus arrhythmia is the impact its symptoms may have on the patient’s quality of life. The main symptoms are non-specific and include palpitations, chest tightness, dizziness, dark haze or fatigue, and decreased exercise tolerance. When sinus arrest is prolonged, patients may experience black haze, transient impairment of consciousness, fainting, and even death in severe cases. In patients with underlying heart disease, inappropriate sinus arrhythmias may exacerbate the progression of pre-existing disease. Sick sinus syndrome may present with symptoms of insufficient blood supply to the heart, brain, and other organs associated with bradycardia. In severe cases, angina pectoris, heart failure, transient impairment of consciousness, or syncope may occur, and may produce symptoms of insufficient blood supply to other organs such as oliguria. Sudden cardiac death can even be caused by cardiac arrest or induced ventricular fibrillation, which needs to be taken seriously. Most sinus arrhythmias, such as sinus tachycardia and sinus bradycardia, can be well controlled with cause-specific treatment and avoidance of triggers, and have little impact on health. Patients with sick sinus syndrome should be treated with pacemaker implantation when medication fails to prevent heart failure or sudden cardiac death. When life-threatening conditions may occur in the presence of sick sinus syndrome, prompt medical attention is required.