Catheter Ablation -> Atrial Fibrillation & Atrial Flutter: -> Ablation Techniques D-PO02 - Poster Session II (ID 47) Poster

D-PO02-193 - A Multi-centre Experience Of Ablation Index To Evaluate Lesion Delivery In Cavotricuspid Isthmus Dependent Atrial Flutter (ID 1052)


Background: Anatomical studies demonstrate significant variation in cavotricuspid isthmus (CTI) architecture. Structural anomalies such as pouches and crypts may impede ablation.
Objective: We hypothesised that ablation index (AI) may further our understanding of energy delivery across the CTI and hence improve procedural efficacy, particularly in anatomically challenging cases.
Methods: 24 patients underwent CTI ablation at two tertiary hospitals. Operators delivered lesions with a target AI of 600Wgs (power 40-50W). Parameters were recorded every 50ms. Post hoc, Visitags were trisected according to CTI position: inferior vena cava (IVC), middle (Mid), or ventricular (V) lesions.
Results: 582 ablation lesions were delivered. For the whole CTI, peak AI correlated with mean impedance drop (ID) (R2=0.92, p<0.0001). However, analysis by anatomical site demonstrated non-linearity Mid CTI (R2=0.15, p=0.21). Accordingly, whilst mean AI was highest Mid CTI (IVC: 475.1±119.1 Wgs, Mid: 538.8±106.4 Wgs, V: 485.2±110.2 Wgs, ANOVA p<0.0001), mean ID was lower (IVC: 10.6±7.3Ω, Mid: 9.1±6.4Ω, V: 10.86±7.2Ω, p=0.027), and rate of ID was slower Mid CTI (IVC: 0.38 Ω/s, Mid: 0.19 Ω/s, V: 0.26 Ohms/s, p<0.0002). Mean contact force was similar at all sites, however temporal variations in contact force (IVC: 7.06mg/ms, Mid: 77.1mg/ms, V: 55.47mg/ms, p=0.002) were greater Mid CTI.
Conclusion: Ablation characteristics vary according to CTI site. Mid CTI, temporal fluctuations in contact force suggest catheter instability, which may explain why increasing AI did not correlate with greater ID at this site. An appreciation of these variations may permit a more prescriptive strategy for CTI ablation.