Catheter ablation for atypical atrial flutter: characterization and recurrence predictors
Authors: Barradas M , Fonseca P , Almeida J , Oliveira M , Goncalves H , Primo J , Tavares A , Martins D , Fontes-Carvalho R 
Published: November 2023

Abstract

Background
Atypical atrial flutter (AFLA) is a macro-reentrant atrial tachycardia not using the cavotricuspid isthmus. Due to recent innovations in technology, catheter ablation has emerged as the most viable option to treat AFLA. Data related to electrophysiologic characteristics and predictor prognostic factors is limited.

Purpose
Our study aimed to analyze long-term outcomes after catheter ablation and to identify predictors for atrial arrhythmia (AA) recurrence (documented atrial fibrillation (AF), atrial tachycardia, or atrial flutter).

Methods
We performed a retrospective single-center review of all consecutive patients treated for AFLA ablation in our center from October 2008 to July 2022. All patients underwent radiofrequency ablation with a 3D mapping system.

Results
From 64 patients (mean age 61.0 ± 11.28 years, 60.9% male and mean follow-up period (FUP) 58.5 ± 47.79 months) 32 (50.0%) had history of previous catheter ablation (35.9% PVI), 14 (21.9%) previous cardiac surgery and 18 (28.1%) corresponded to AFLA not related to ablation or previous cardiac surgery. Most patients (79.7%) had paroxysmal AFLA, 50% concomitant AF, 50% were on anthyarrhytmic drugs (AAD) and 35.9% underwent previous electrical cardioversion (ECV). Mean left ventricular ejection fraction was 55.1 ± 10.44%, 25 (39.1%) patients had moderate to severe left atrial (LA) dilatation and 11 (17.2%) right atrial (RA) dilatation. Low-voltage areas (LVA) were identified in 38 (59.4%) patients. A total of 81 AFLA were present or induced (1.3 ± 0.74 AFLA per patient) and in 7 (10.9%) patients an atrial arrhythmia was not induced. The LA was involved in 70.3% and the RA in 29­.7%. The location of the circuit is described in the table 1 as well as ablation details. Acute procedural success was achieved in 87.5%. AA recurrence occurred in 32.8% at 1 year, 35.9% at 2 years and 40.6% at FUP (14.1 ± 41.41 months after ablation), for which 3.1% had re-ablation (17.0 ± 23.99 months after index ablation), 5 (7.8%) ECV and 15 (23.4%) maintained or initiated AAD. 10 (15.6%) went to the emergency department (ED) due to AA (mean time since ablation until the first ED visit 31.4 ± 69.07 months). One patient had an ischemic stroke and 6 patients cardiovascular (CV) hospitalization. There were 5 non-CV deaths and there were no CV deaths. Female gender was an independent predictor of AA recurrence (15 (60.0%) vs 11 (31.4%), hazard ratio (HR): 3.496 [95% CI: 1.761 – 200.000], p=0.046) as well as moderate or severe LA dilatation (14 (51.9%) vs 3 (17.6%), HR 3.257 [95%CI 1.715 – 38.462], p=0.033). The presence of fibrosis or the ablation strategy were not associated with recurrence.

Conclusion
AFLA most frequently originated in the LA, LVA were frequent, as well as the presence of structural changes and previous ablation or cardiac surgery. In our cohort study, female gender and the severity of LA dilatation were independent predictors of AA recurrence.