Atrial tachycardia is relatively uncommon in clinical practice. Like atrial flutter, atrial tachycardia is more difficult to control the number of heartbeats by medication. Depending on the mechanism of attack, atrial tachycardia can be divided into three types: focal atrial tachycardia (localized increase in atrial muscle autoregulation, i.e., due to a trigger mechanism), sinus regurgitation atrial tachycardia (formation of a regurgitant loop between the sinus node and the atria), and atrial regurgitation atrial tachycardia. Atrial tachycardia is sometimes not clearly distinguishable from atrial flutter, but only by the frequency of atrial excitation (electrical impulses delivered by the atria). The success rate of ablation therapy for atrial tachycardia is 90 to 100%, with a high probability of cure and very few serious complications. Ablation may be considered in the following cases: when drug therapy is ineffective, when drug therapy has significant side effects or when the patient does not want to take drug therapy for a long time. Focal atrial tachycardia is caused by a point in the atrium where the myocardium delivers excessively fast electrical impulses that take a certain amount of time to conduct from that point (the lesion) to the rest of the atrium. Accordingly, the closer to the lesion, the earlier the electrical impulses should be recorded, and the earliest electrical impulses should be recorded at the source – the lesion. It is based on this principle that the catheter capable of recording electrical pulses is used to search in the right or left atrium until the earliest place of electrical pulses is found and then ablation is performed at that place. This is in fact the basic principle of ablation of all tachyarrhythmias caused by trigger mechanisms. Most focal atrial tachycardias originate in the right atrium, and left atrial focal atrial tachycardias are relatively rare; in children, left atrial tachycardias are somewhat more common. Sinus regurgitant atrial tachycardia is very rare, and although it is an arrhythmia due to a regurgitant mechanism, it is treated in a specific way, similar to the ablation of triggered atrial tachycardia, by searching for the earliest point of electrical impulse delivery in the atria, i.e., the earliest point of atrial excitation. Since the sinus node has a fixed anatomical location, a suitable ablation site is usually found at the junction of the superior vena cava and the right atrium. Atrial fold tachycardia is often associated with underlying cardiac disease or previous atrial surgery. The treatment of this type of atrial tachycardia is similar to that of atypical atrial flutter in that the location of the folding loop is determined and then ablation is performed. Premature atrial tachycardia is very common and results from a trigger mechanism. Ablation of atrial tachycardia is not clinically aggressive because it usually has no serious clinical consequences and because it often has foci with more than one point of origin, making ablation difficult. Ablation may be considered only if the following conditions are present: the symptoms of atrial prematureness are very pronounced, the effect of drug therapy is unsatisfactory, the episodes are frequent (e.g., >20,000 atrial prematureness in 24 hours) and suitable for ablation (continuous and stable atrial prematureness rather than temporal), and the origin of atrial prematureness can be initially determined from the body electrocardiogram to be at a single site or predominantly at a single site. Atrial prematureness is ablated in the same way as focal atrial tachycardia.