Prospective evaluation of entrainment mapping as an adjunct to new-generation high-density activation mapping systems of left atrial tachycardias

Background: Identification of atrial tachycardia (AT) mechanism remains challenging. Objective: We sought to investigate the added value of entrainment maneuvers (EM) when using new high-density activation mapping (HDAM) technologies for the identification of complex left ATs. Methods: Thirty-six consecutive complex ATs occurring after ablation of persistent atrial fibrillation were prospectively analyzed. The AT mechanism was diagnosed in 2 steps by 2 experts: (1) based on HDAM only (Coherent module, CARTO, Biosense Webster Inc., Irvine, CA) and (2) with additional analysis from EM. Results: EM resulted in atrial fibrillation in 1 patient, who was excluded from the analysis. Ten of 11 single loop macroreentries identified by HDAM were confirmed by EM. Only 4 of 14 double loop macroreentries identified by HDAM wereconfirmed by EM (in 10 patients, EM unmasked passive activation of one of the visual circuits). One sole microreentry circuit identified by HDAM was confirmed by EM. A combination of macro- and microreentry circuits was visualized in 3 ATs using HDAM. However, EM revealed passive activation of the visual macroreentrant loop in 2 of these 3 cases. By using HDAM in 6 of 35 ATs (17%), no univocal mechanism could be identified, whereas EM finally enabled the diagnosis of 5 microreentry circuits and 1 macroreentrant AT. All the diagnoses made from EM in addition to HDAM were confirmed by ablation. Conclusion: Entrainment maneuvers are still useful during mapping of complex left ATs, mostly to differentiate active from passive macroreentrant loops and to demonstrate microreentry circuits.