Key result
Low baseline impedance linked to ~66% lower AF recurrence versus high impedance.
Why the study?
Impedance is an important factor for lesion formation, but its influence on the outcomes of AF catheter ablation guided by ablation index was unclear.
Does baseline impedance predict atrial fibrillation recurrence in patients undergoing catheter ablation for paroxysmal atrial fibrillation guided by ablation index?
Cohort (n=101)
No
Does baseline impedance predict atrial fibrillation recurrence in patients undergoing catheter ablation for paroxysmal atrial fibrillation guided by ablation index?
Absolute Event Rate: 90.7% vs 72.3%
p-value: p=<0.05
Higher baseline impedance during ablation index-guided pulmonary vein isolation for paroxysmal atrial fibrillation is associated with an increased risk of arrhythmia recurrence.
May refine recurrence risk stratification after ablation index-guided PVI; hypothesis-generating for impedance-targeted strategies.
OBJECTIVE: Ablation index (AI) is an effective ablation quality marker. Impedance is also an important factor for lesion formation. The present study evaluated the influence of the baseline impedance in the effect of ablation for atrial fibrillation (AF) guided by AI. METHODS: This was a retrospective study. 101 patients with paroxysmal AF (PAF) were enrolled. All patients underwent radiofrequency ablation guided by the same AI strategy. The ablation strategy was pulmonary vein (PV) isolation with non-PV triggers ablation. The baseline impedance of the ablation points was recorded. The patients were followed up every 3 months or so. RESULTS: During a median follow-up of 12 (4-14) months, freedom from AF/atrial tachycardia recurrence were 82.2%. No difference existed in baseline characteristics between the success group and the recurrence group. The average baseline impedance was 124.3 ± 9.7 Ω. The baseline impedance of the ablation points in success group was lower compared to the recurrence group (122.9 ± 9.4 vs. 130.5 ± 8.8 Ω, P < 0.01). The ratio of impedance drop in the success group was higher than the recurrence group ([8.8 ± 1.4]% vs. [8.1 ± 1.2]%, P = 0.03). Multivariate analysis revealed that baseline impedance, PAF duration and AI were the independent predictors of AF recurrence. The cumulative free of recurrence rate of low-impedance group (≤ 124 Ω, n = 54) was higher than that of high-impedance group. CONCLUSION: Baseline impedance correlates with clinical outcome of radiofrequency ablation for PAF guided by AI. Higher impedance in the same AI strategy may result in an ineffective lesion which probably causes recurrence.
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Sun et al. (2022) conducted a cohort in Paroxysmal atrial fibrillation (n=101). Low baseline impedance (≤ 124 Ω) during radiofrequency ablation vs. High baseline impedance (> 124 Ω) during radiofrequency ablation was evaluated on Freedom from AF/atrial tachycardia recurrence (p=<0.05). Higher baseline impedance was an independent predictor of atrial fibrillation recurrence (HR 1.06), with low-impedance patients (≤ 124 Ω) achieving 90.7% freedom from recurrence compared to 72.3% in high-impedance patients.
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