Focal atrial tachycardia and its differentiation from macroreentrant atrial tachycardia

Atrial tachycardia (AT) can be broadly categorized based on its mechanism as focal or reentrant. Focal AT is characterized as a fast rhythm from a discrete origin, discharging at a rate that is generally regular, and conducting in a centrifugal manner throughout the atria. Focal AT can present at any age and can occur in both normal (idiopathic) and diseased hearts (structural heart disease). It represents 3–17% of supraventricular tachycardia (SVT) cases referred for ablation. Macroreentrant ATs are frequently associated with regions of atrial scar and are often noted in the context of structural heart disease, prior cardiac surgery and increasingly after catheter ablation of atrial fibrillation (AF). Focal versus macroreentrant AT and common sites of focal atrial tachycardia are also discussed in this chapter.