Atrial Tachycardias After AF Ablation
ATs of new onset make up to 50% of all arrhythmias observed following catheter-based ablation of AF.253,436,507,508,622,623, 624,625,630,870,871,995,996,997,998,999,1000,1001,1002 Most of these tachycardias originate in the LA, although RA cavotricuspid isthmus (CTI)-dependent flutters might also occur. Patients with a regular AT of new onset might complain of worsening symptoms due to a faster mean ventricular rate (frequently 2:1 ventricular response) than that during AF preablation. Rhythm control is often difficult with AADs.
The mechanisms underlying regular LA tachycardias following AF ablation include focal microreentrant tachycardias originating from reconnected PV ostia or macroreentrant tachycardias around anatomic obstacles or scar from intrinsic LA disease or prior ablation(s) (Figure 5).447,508,933, 998 Occurrence of early AT within 3 months after ablation predicts occurrence of both late AT and AF.1003,1004,1005 However, because up to 49% of ATs resolve with time, ablation should not be undertaken for early AT occurrence unless symptoms cannot be controlled.1003 Initial treatment should include electrical cardioversion and AADs. Because Vaughan Williams Class Ic antiarrhythmic agents promote slow conduction that can facilitate macroreentrant tachycardias, Class III antiarrhythmic agents (dofetilide, sotalol, or amiodarone), together with negative dromotropic agents, are typically preferred. For those with intolerable symptoms or continued late AT recurrence, detailed activation and entrainment mapping of the tachycardia results in effective ablation in approximately 90% of patients.447,622,623,624,1006,1007,1008