Impact of impedance decrease during radiofrequency current application for atrial fibrillation ablation on myocardial lesion and gap formation

Figures

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  Figure 1. Impedance curve during radiofrequency current application. The change in impedance during radiofrequency current application is shown in the upper panel. (A) Impedance decrease was measured as shown by the arrow. If the impedance changed dramatically, (B) the application was stopped. The stable value of impedance before the impedance change was then measured manually and the impedance decrease was calculated (lower panel)

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  Figure 2. Relationships between FTI, PIT, and ΔTrpI. The relationships of FTI and PIT to ΔTrpI are shown in Figure 2. There were significant correlations between FTI and ΔTrpI (A), and between PIT and ΔTrpI (B) (ΔTrpI = 23 + 0.18 × FTI, r 2 = .19, P = .0090; ΔTrpI = −0.076 + 0.45 × PIT, r 2 = .21, P = .0058). However, the correlation coefficients were not very high. FTI, force‐time integral; PIT, product of impedance decrease during the application and application time, ΔTrpI, increase in cardiac troponin I after 50 radiofrequency applications

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  Figure 3. Relationship between PIFT and ΔTrpI. PIFT had a significantly better correlation with ΔTrpI than did FTI or PIT (ΔTrpI = 34 + 0.016 × PIFT, r 2 = .29, P = .0010). PIFT, product of impedance decrease and FTI. Other abbreviations as in Figure 2

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  Figure 4. Receiver operating characteristic curve analyses for PIT and PIFT. Receiver operating characteristic curve analyses for PIT and PIFT are shown in Figure 4. The analyses revealed that the area under the curve for predicting reconnection during the session was 0.69 for PIT and 0.71 for PIFT, with the optimal cutoff values for predicting reconnection being 280 Ω.s for PIT (sensitivity 89%, specificity 50%) (A) and 5200 g.Ω.s for PIFT (sensitivity 78%, specificity 63%) (B). Abbreviations as in Figure 3