The occurrence of left atrial tachycardias (AT) after catheter ablation for atrial fibrillation (AF) is common, especially after more extensive ablation of persistent AF. These AT are invariably symptomatic and often do not respond to medical therapy. The initial strategy involves ventricular rate control, cardioversion, and observation as some tachycardias may resolve with time. For persistent ATs, effective management frequently requires catheter intervention. Careful characterization of the tachycardia mechanism is essential in designing an effective ablation strategy that would also avoid further creation of pro-arrhythmic substrate. With this review, we summarize the incidence, mechanism, diagnosis and treatment of ATs occurring after AF ablation.tachycardias. Using this approach, AT incidence has ranged from 10% 9 to 30%. 3,8,10,11 When ablation of complex fractionated electrograms alone is performed, post ablation AT may occur in approximately 15-25% of patients.5, 12 With a more extensive ablation involving PVI isolation, empiric lines and electrogram based ablation all performed during the same procedure, the incidence of AT has been reported as high as 50%.3 , 7, 13, 14 Early versus Late Recurrence AT can occur early or late after AF ablation. Early ATs are defined as AT occurring within 3 months after ablation and late ATs those that occur after the 3 month post-ablation period. The incidence of AT is particularly high in the early period post ablation with 89% of all ATs occurring the first month, 9% in the second and 2% in the third month.13 Although early AT occurrence does predict late AT or recurrence of AF 13, 15 approx imately one-third of tachycardias may resolve with conservative management. 16 The presence of hypertension, persistent AF, left atrial (LA) size>4 cm, presence of structural heart disease and the lack of a successful ablation of all targeted PV have been independently correlated with early atrial tachyarrhythmias occurrence. 16,17 The much higher incidence of AT during the early post-ablation period may partially be related to radiofrequency related inflammatory changes. Until the development of well defined fibrosis, tissue edema and inflammation can be pro-arrhythmic. In addition, like in all cases of acute local cardiac inflammation, ablation is likely to mount a systemic inflammatory response. Inflammation both at tissue and systemic levels are related to the development of arrhythmias. ATs that persist after a 3 month period or occur late after AF ablation typically do not usually resolve spontaneously and warrant intervention.
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Mechanism and PreventionPost ablation ATs can be divided based on their mechanism as focal or macro-reentrant [ Figure 1]. The mechanism of AT is usually related to the www.jafib.com