Arrhythmias may or may not cause sudden death, such as ventricular fibrillation, for example, atrial premature beats. Arrhythmias include a variety of types that may be more severe in some patients, such as ventricular fibrillation, ventricular tachycardia, and preexcitation syndrome with atrial fibrillation. These arrhythmias can lead to severe hemodynamic disturbances and risk of sudden death, requiring emergency treatment and resuscitation, as well as electrical defibrillation in the event of an attack. On the other hand, patients with arrhythmias such as atrial premature and episodic ventricular premature may experience palpitations and other related symptoms, but they do not have serious hemodynamic disorders, and sudden death rarely occurs. Patients who develop arrhythmias should be careful to assess the risk, and those at high risk should be treated promptly to avoid death.