RESUMEN
Background: Atypical left atrial flutter (AFL) may be macroreentrant or spatially localized. The relationship between the critical isthmus (CI) for localized reentry with sinus rhythm (SR) conduction slowing has not been systematically examined. Objective: To examine the correlation between CI sites for localized AFL (L-AFL) and deceleration zones (DZ) identified by isochronal late activation mapping (ILAM) during baseline rhythm. Methods: Patients with localized AFL who underwent high-density activation mapping of both SR and AFL were retrospectively analyzed. L-AFL was defined as reentry restricted to 2 wall segments of the left atrium. CI was defined by activation mapping and sites of successful termination during ablation. DZ, defined as >3 isochrones within 1 cm radius during baseline rhythm, were correlated to the locations of the CI. Results: Thirty-one consecutive patients that underwent detailed sinus rhythm and AFL high-density activation maps were analyzed at 3 centers. A mean 4060 ± 3275 and 6209 ± 8656 points were collected in ILAM and AFL activation maps, respectively. At least 1 DZ (1.7 ± 0.77) was identified in all patients. ILAM showed 3.27 ± 0.52 isochrones per DZ (168 ± 32 ms), and co-localized to CI sites at a distance of 6.7 ± 3 mm. A total of 34% ± 14% of the AFL cycle length was contained within 0.5 cm of the DZ. Conclusions: In patients with L-AFL, CI co-localized with DZ during baseline rhythm, suggesting that DZ mapping during SR may yield candidate targets for ablation as an adjunct to pulmonary vein isolation to prevent a subtype of AFL.
RESUMEN
OBJECTIVES: This study sought to describe arrhythmia characteristics using ultra-high density (UHD) mapping of macro-re-entrant left atrial flutter (LAFL) which propagate via epicardial bridging (EB), and highlight regional anatomy that poses challenges to ablation. BACKGROUND: Three-dimensional propagation via EB may contribute to the maintenance and complexity of LAFL. METHODS: UHD activation maps of macro-re-entrant LAFL created with a mini-electrode basket catheter were analyzed between June 2015 and March 2020. EB was defined as a region of wave front discontinuity with focal activation distal to an activation gap. Regions of EB were correlated with anatomic structures known to have specialized epicardial bundles. Direct evidence of EB was obtained via percutaneous epicardial access (n = 22) with simultaneous epicardial recordings during endocardial activation gaps. RESULTS: Among 159 patients who underwent LA endocardial procedures with UHD mapping, 43 patients with 47 macro-re-entrant LAFLs were included in this analysis. Evidence of EB was present in 38% of LAFLs. Four anatomic areas of EB were observed: coronary sinus (17%), vein of Marshall (28%), Bachmann's region (33%), and region of the septopulmonary bundle (22%). All 47 LAFLs were successfully ablated. Percutaneous epicardial mapping yielded direct evidence for EB in 9 patients with LAFL (41%). At 23 ± 13 months, 70% remained free from recurrent LAFL. CONCLUSIONS: In a selected population, UHD mapping demonstrates evidence of EB in 38% of cases of LAFL involving 4 distinct epicardial anatomic regions. Identification of discontinuous 3-dimensional activation patterns with attention to correlative regional LA anatomy may reduce the incidence of ablation failures for complex re-entry.
