Ablation of atypical atrial flutters using ultra high density-activation sequence mapping

Abstract

Purpose: The purpose of this study was to evaluate ultra high density-activation sequence mapping (UHD-ASM) for ablating atypical atrial flutters.

Methods: For 23 patients with 31 atypical atrial flutters (AAF), we created UHD-ASM.

Results: Demographics age = 65.3 ± 8.5 years, male = 78%, left atrial size = 4.66 ± 0.64 cm, redo ablation 20/23(87%). AAF were left atrial in 30 (97%). For each AAF, 1273 ± 697 points were used for UHD-ASM. Time to create and interpret the UHD-ASM was 20 ± 11 min. For every AAF, the entire circuit was identified. Thirty (97%) were macroreentry. AAF cycle length was 267 ± 49 ms, and the circuit length was 138 ± 38 mm (range 35-187). Macroreentry atrial flutters took varied pathways, but each had an area of slow conduction (ASC) averaging 16 ± 6 mm (range 6-29) in length. Entrainment was not utilized. We targeted the ASC and ablation terminated AAF directly in 19/31 (61.3%) and altered AAF activation in 7/31 (22.6%), all of which terminated directly with additional mapping/ablation. AAF degenerated to atrial fibrillation in 2/31 (6.5%) with RF and could not be reinduced after ASC ablation. Median time from initial ablation to AAF termination was 64 s. Thus, 28/31 (90.3%) terminated with RF energy and/or could not be reinduced after ASC ablation. At 1 year of follow-up, 77% were free of atrial tachycardia or atrial flutter and 61% were free of all atrial arrhythmias.

Conclusions: Using rapidly acquired UHD-ASM, the entire AAF circuit as well as the target ASC could be identified. Most AAF were left atrial macroreentry. Ablation of the ASC or microreentry focuses directly terminated or eliminated AAF in 90.3% without the need for entrainment mapping.

Keywords: Activation mapping; Atrial flutter; Atrial flutter ablation; Atypical atrial flutter; Left atrial flutter.

Fig. 1

Left atrial anteroseptal flutter with an area of slow conduction between the septal scar and a previously isolated right superior pulmonary vein. (RSPV right superior pulmonary vein, RIPV right inferior pulmonary vein, LSPV left superior pulmonary vein, LAA left atrial appendage). See Appendix 1 for the propagation map of this atrial flutter

Fig. 2

Double loop left atrial flutter with anterior loop going clockwise along the inferior mitral annulus and up the septum and the posterior loop going counterclockwise around the left pulmonary veins with a common segment of slow conduction between the left atrial appendage and the left inferior pulmonary vein. (LIPV left inferior pulmonary vein, other abbreviations as in Fig. 1). See Appendix 2 for the propagation map of this atrial flutter

Fig. 3

Complex mitral isthmus flutter. Much of the atrial flutter circuit is around the mitral valve. However, the circuit deviates toward the critical area of slow conduction between LAA and the LIPV. It then returns to the mitral valve via conduction through the LAA. Abbreviations as in Figs. 1 and 2. See Appendix 3 for the propagation map of this atrial flutter

Fig. 4

Kaplan-Meier curves for freedom from atrial tachycardia and flutter (top panel) and freedom from all atrial arrhythmias (bottom panel) following ablation for atypical atrial flutters