Incidence, electrophysiological characteristics, and long-term follow-up of perimitral atrial flutter in patients with previously confirmed mitral isthmus block

Panagiotis Ioannidis; Evangelia Christoforatou; Theodoros Zografos; Panagiotis Charalambopoulos; Konstantinos Kouvelas; Georgios Christoulas; Periklis Syros; Georgios Tsitsinakis; Theodora Kappou; Andreas Tsoumeleas; Sotirios Floros; Dimitrios Tagoulis; Ioannis Ntarladimas; Ioannis Tagoulis; Dimitrios Avzotis; Antonis S Manolis; Charalambos Vassilopoulos

doi:10.1002/joa3.12545

Incidence, electrophysiological characteristics, and long-term follow-up of perimitral atrial flutter in patients with previously confirmed mitral isthmus block

J Arrhythm. 2021 May 12;37(3):584-596. doi: 10.1002/joa3.12545. eCollection 2021 Jun.

Authors

Panagiotis Ioannidis¹, Evangelia Christoforatou¹, Theodoros Zografos¹, Panagiotis Charalambopoulos¹, Konstantinos Kouvelas¹, Georgios Christoulas¹, Periklis Syros¹, Georgios Tsitsinakis¹, Theodora Kappou¹, Andreas Tsoumeleas¹, Sotirios Floros¹, Dimitrios Tagoulis¹, Ioannis Ntarladimas¹, Ioannis Tagoulis², Dimitrios Avzotis¹, Antonis S Manolis³, Charalambos Vassilopoulos¹

Affiliations

¹ Heart Rhythm Center Athens Bioclinic Athens Greece.
² First Cardiology Department Red Cross Hospital Athens Greece.
³ First Department of Cardiology Athens University School of Medicine Athens Greece.

Abstract

Introduction: After mitral isthmus (ΜΙ) catheter ablation, perimitral atrial flutter (PMF) circuits can be maintained due to the preservation of residual myocardial connections, even if conventional pacing criteria for complete MI block are apparently met (MI pseudo-block). We aimed to study the incidence, the electrophysiological characteristics, and the long-term outcome of these patients.

Methods: Seventy-two consecutive patients (mean age 62.4 ± 10.2, 62.5% male) underwent MI ablation, either as part of an atrial fibrillation (AF) ablation strategy (n = 35), or to treat clinical reentrant atrial tachycardia (AT) (n = 32), or to treat AT that occurred during ablation for AF (n = 5). Ιn all patients, the electrophysiological characteristics of PMF circuits were studied by high-density mapping.

Results: Mitral isthmus block was successfully achieved in 69/72 patients (95.6%). Five patients developed PMF after confirming MI block. In these patients, high-density mapping during the PMF showed a breakthrough in MI with extremely low impulse conduction velocity (CV). In contrast, in usual PMF circuits that occurred after AF ablation, the lowest CV of the reentrant circuit was of significantly higher value (0.07 ± 0.02 m/s vs 0.25 ± 0.07 m/s, respectively; P < .001). Patients presented with clinical AT had better prognosis in maintaining sinus rhythm after MI ablation compared with patients presented with AF.

Conclusion: Perimitral atrial flutter with MI pseudo-block may be present after MI ablation and has specific electrophysiological features characterized by remarkably slow CV in the MI. Thus, even after MI block is achieved, a more detailed mapping in the boundaries of the ablation line or reinduction attempts may be needed to exclude residual conduction.

Keywords: atrial fibrillation; atrial tachycardias; catheter ablation; linear lesions; mitral isthmus; perimitral atrial flutter; pseudo‐block.