Prospective use of Ablation Index targets improves clinical outcomes following ablation for atrial fibrillation

J Cardiovasc Electrophysiol. 2017 Sep;28(9):1037-1047. doi: 10.1111/jce.13281. Epub 2017 Jul 26.

Abstract

Aims: Late recovery of ablated tissue leading to reconnection of pulmonary veins remains common following radiofrequency catheter ablation for AF. Ablation Index (AI), a novel ablation quality marker, incorporates contact force (CF), time, and power in a weighted formula. We hypothesized that prospective use of our previously published derived AI targets would result in better outcomes when compared to CF-guided ablation.

Methods: Eighty-nine consecutive drug-refractory AF patients (49% paroxysmal) underwent AI-guided ablation (AI-group). AI targets were 550 for anterior/roof and 400 for posterior/inferior left atrial segments. Procedural and clinical outcomes of these patients were compared to 89 propensity-matched controls who underwent CF-guided ablation (CF-group). All 178 procedures were otherwise similar, and both groups were followed-up for 12 months. The last 25 patients from each group underwent analysis of all VisiTags™ for ablation duration, CF, Force-Time Integral, and impedance drop.

Results: First-pass pulmonary vein isolation (PVI) was more frequent in AI-group than in CF-group (173 [97%] vs. 149 [84%] circles, P < 0.001), and acute PV reconnection was lower (11 [6%] vs. 24 [13%] circles, P = 0.02). Mean PVI ablation time was similar (AI-group: 42 ± 9 vs. CF-group: 45 ± 14 minutes, P = 0.14). Median impedance drop for AI-group was significantly higher than in CF-group (13.7 [9-19] Ω vs. 8.8 [5.2-13] Ω, P < 0.001). Two major complications occurred in CF-group and none in AI-group. Atrial tachyarrhythmia recurrence was significantly lower in AI-group (15 of 89 [17%]) than in CF-group (33 of 89 [37%], P = 0.002).

Conclusion: AI-guided ablation is associated with significant improvements in the incidence of acute PV reconnection and atrial tachyarrhythmia recurrence rate compared to CF-guided ablation, potentially due to creation of better quality lesions as suggested by greater impedance drop.

Keywords: ablation index; atrial fibrillation; contact force; impedance drop; pulmonary vein isolation.

MeSH terms

  • Atrial Fibrillation / physiopathology
  • Atrial Fibrillation / surgery*
  • Catheter Ablation / methods*
  • Female
  • Follow-Up Studies
  • Heart Atria / physiopathology*
  • Heart Conduction System / physiopathology
  • Heart Conduction System / surgery*
  • Humans
  • Male
  • Middle Aged
  • Postoperative Period
  • Prospective Studies
  • Pulmonary Veins / surgery*
  • ROC Curve
  • Treatment Outcome