In typical atrial flutter ablation, peak ablation index correlated with mean impedance drop across the whole CTI (R2=0.89, p<0.0001), though this relationship was non-linear at the middle CTI.
Observational (n=38)
Yes
Does ablation index accurately reflect effective lesion delivery across different anatomical sites of the cavotricuspid isthmus during atrial flutter ablation?
Ablation index may not reliably predict lesion efficacy at the mid-cavotricuspid isthmus due to catheter instability, suggesting a need for careful attention to contact force and angle during atrial flutter ablation.
Effect estimate: R2 0.89
p-value: p=<.0001
Abstract Background Anatomical studies demonstrate significant variation in cavotricuspid isthmus (CTI) architecture. Methods Thirty‐eight patients underwent CTI ablation at two tertiary centers. Operators delivered 682 lesions with a target ablation index (AI) of 600 Wgs. Ablation parameters were recorded every 10–20 ms. Post hoc, Visitags were trisected according to CTI position: inferior vena cava (IVC), middle (Mid), or ventricular (V) lesions. Results There were no complications. 92.1% of patients (n = 35) remained in sinus rhythm after 14.6 ± 3.4 months. For the whole CTI, peak AI correlated with mean impedance drop (ID) (R 2 = 0.89, p < .0001). However, analysis by anatomical site demonstrated a non‐linear relationship Mid CTI (R 2 = 0.15, p = .21). Accordingly, while mean AI was highest Mid CTI (IVC: 473.1 ± 122.1 Wgs, Mid: 539.6 ± 103.5 Wgs, V: 486.2 ± 111.8 Wgs, ANOVA p < .0001), mean ID was lower (IVC: 10.7 ± 7.5Ω, Mid: 9.0 ± 6.5Ω, V: 10.9 ± 7.3Ω, p = .011), and rate of ID was slower (IVC: 0.37 ± 0.05 Ω/s, Mid: 0.18 ± 0.08 Ω/s, V: 0.29 ± 0.06 Ω/s, p < .0001). Mean contact force was similar at all sites; however, temporal fluctuations in contact force (IVC: 19.3 ± 12.0 mg/s, Mid: 188.8 ± 92.1 mg/s, V: 102.8 ± 32.3 mg/s, p < .0001) and catheter angle (IVC: 0.42°/s, Mid: 3.4°/s, V: 0.28°/s, p < .0001) were greatest Mid CTI. Use of a long sheath attenuated these fluctuations and improved energy delivery. Conclusions Ablation characteristics vary across the CTI. At the Mid CTI, higher AI values do not necessarily deliver more effective ablation; this may reflect localized fluctuations in catheter angle and contact force.
Maclean et al. (Tue,) conducted a observational in typical atrial flutter (n=38). Cavotricuspid isthmus (CTI) ablation was evaluated on Correlation between peak ablation index and mean impedance drop (R2 0.89, p=<.0001). In typical atrial flutter ablation, peak ablation index correlated with mean impedance drop across the whole CTI (R2=0.89, p<0.0001), though this relationship was non-linear at the middle CTI.