The prognosis of arrhythmias is related to the etiology, triggers, and evolution of the arrhythmia whether it leads to severe hemodynamic disturbances. Arrhythmias that occur in the absence of organic heart disease include premature beats, supraventricular tachycardia, and atrial fibrillation, and most of them have a good prognosis; however, patients with QT prolongation syndrome have ventricular premature beats, which can easily evolve into polymorphic ventricular tachycardia or ventricular fibrillation, and have a poor prognosis; patients with prodromal syndrome have atrial flutter or atrial fibrillation with a very fast ventricular rate, which, in addition to causing severe hemodynamic changes, may evolve into ventricular fibrillation. However, most of them can be controlled by DC resuscitation and pharmacological treatment, and thus the prognosis is still good. Ventricular tachyarrhythmias and complete AV block with extremely slow heart rate, ventricular autonomic rhythm, and severe pathological sinus node syndrome can rapidly lead to circulatory dysfunction and immediately threaten the patient’s life. The prognosis of AV block due to intra-atrial node block differs significantly from that of AV block due to double bundle branch (triple branch) block, with the former having a somewhat better prognosis and the latter a worse prognosis. If the arrhythmia occurs on the basis of organic heart disease, the prognosis is generally good if the arrhythmia itself does not cause obvious hemodynamic disorders and does not easily evolve into serious arrhythmia, but if the underlying heart disease is serious, especially if it is accompanied by cardiac insufficiency or acute myocardial ischemia, the prognosis is generally somewhat poor. Wang Xinhua, Department of Cardiology, Shanghai Renji Hospital