MAPping with fragmentation analysis in patients with atypical atrial FLUtter using the RHYthmia navigation system (MAP-FLURHY study)

Abstract

Abstract Background Atypical atrial flutter (AAFL) circuits use areas of slow conduction which can be visualized as fragmented electrograms (fEGMs). Purpose To test an ablation strategy based on the identification and ablation of spots with fEGMs in AAFL. Methods The MAP-FLURHY study prospectively included all AAFL ablations with Rhythmia in our Center from June 2016 to June 2019. Patients with non-mappable AAFL, frequent conversion to atrial fibrillation, or cavotricuspid isthmus-dependent flutters were excluded from analysis. The IntellaMap ORION catheter was used to detect fragmentation areas, arbitrarily defined as fEGMs >70ms. Entrainment was used to check if these areas belonged to the AAFL circuit. Ablation targeted the longest fEGM within the circuit (return cycle <30ms): focal ablation for microreentries, and lines including the fEGMs for macroreentries. Ablation success was defined as conversion to sinus rhythm or another flutter. Procedural success was defined as successful ablation of all inducible flutters. Follow-up included visits with 24h Holter ECG at 3–6-12 months. Results 50 Patients received ablation (Figure). 27 Patients (70.6±13.1 years; 10 females; LVEF 57%±13%) with 44 mappable AAFLs were included in the analysis (Table). All AAFLs showed areas with fEGMs (106 areas; 2.4 areas per flutter). 42/44 AAFLs had fEGMs within the circuit, which were target of ablation. Ablation success: 34/36 AAFLs (94%); success could not be assessed in 6 circuits, due to mechanical conversion to sinus rhythm onto the target fEGM. Fragmented areas within the AAFL circuits (n=51) were longer (110±30 vs 90±15 ms, p<0.001) but had similar voltage (0.34±0.25 vs 0.36±0.26 mV) than areas outside the circuits (n=45). A fEGM duration >100ms/>40% of the cycle length predicted to be a successful site for ablation with 72.3%/73.8% specificity. Procedural success was achieved in 24/27 patients (89%). Excluding a 2-month blanking period, mean survival free from atrial arrhythmias was 19 (95% CI: 12.6–25.5) months. 57% of the patients were free from atrial arrhythmias at 1 year. Conclusions Most AAFLs had detectable fEGMs which could be target of ablation with high efficacy. Figure 1 Funding Acknowledgement Type of funding source: None