Incidence and location of residual gaps identified by a high-density grid-style catheter after PVI is confirmed by pacing the ablation lines

Funding Acknowledgements

Type of funding sources: None.

Background

The continual pursuit of more durable pulmonary vein isolation (PVI) has led ablationists to evaluate many different techniques for confirming isolation. One such technique involves using the ablation catheter to pace along the ablation lines, ensuring loss of pace capture. Initial observations from a small cohort of patients suggested that a high-density, grid style mapping catheter (HD Grid) enabling simultaneous recording of adjacent bipolar EGMs in two directions (HD Wave) may identify residual gaps that are missed when using the technique of pacing the ablation line in isolation. The true incidence of these residual gaps as identified in a large patient population has not been previously reported.

Purpose

To quantify in a large cohort of AF ablation patients, the presence of residual gaps identified by HD Grid which are missed by a technique of pacing along the ablation lines with the ablation catheter.

Methods

Self-reported data was prospectively collected in AF radiofrequency ablation procedures in which PVI was first confirmed by pacing along the ablation line followed by assessment using the HD Grid. Procedural characteristics and acute outcomes, including the incidence and location of gaps post-ablation, were analyzed.

Results

Data was collected in 111 AF ablation procedures performed in 18 centers across the United States and Europe. Paroxysmal (PAF), persistent (PersAF), and longstanding persistent AF (LsPersAF) accounted for 60.4%, 33.3%, and 6.3% of cases, respectively. Overall, 64.0% of ablations were de novo procedures. Following ablation, PVI was confirmed in all cases by pacing the ablation line with an average output of 9.1 ± 2.6mA and pulse width of 2.1 ± 0.5ms. Adenosine was administered in 3.6% of cases, isoproterenol in 3.6%, and a combination in 0.9%. PVI was then reassessed with HD Grid using a variety of techniques including exit block (91.0%), voltage mapping (82.0%), loss of pace capture along the ablation lines (47.7%), and entrance block (27.0%); note: total exceeds 100% as more than one technique may be used in a single case. A second dose of adenosine was administered in 2.7% of cases; isoproterenol in 2.7%. The HD Wave configuration was used in 96.4% of cases. HD Grid identified a total of 130 gaps in 65 (58.6%) patients, which were missed by pacing the ablation line (Figure 1).

Conclusions

In over half of the patients evaluated, the HD Grid identified residual PVI gaps that were missed when isolation was confirmed by using the ablation catheter to pace the ablation lines. These results suggest that the pacing technique, used in isolation, is not sufficient for complete gap detection. One limitation of this analysis was the use of a workflow which consistently assessed PVI with the HD Grid following confirmation of isolation by pacing the ablation lines. Despite this limitation, the rate at which residual gaps were identified is noteworthy and likely warrants additional study. Abstract Figure.

P1028Incidence and location of residual gaps identified by a high-density grid-style mapping catheter after PVI is confirmed by pacing the ablation lines

Background

 Durable pulmonary vein isolation (PVI) is critical to the clinical success of ablation for treatment of atrial fibrillation (AF). Pacing along the ablation line (often using the ablation catheter), is one technique that is commonly used for confirmation of PVI. While this technique is common in practice, it has not been systematically evaluated against other methods for confirming PVI. A high-density grid-style mapping catheter (HD Grid) enabling simultaneous recording of adjacent bipolar EGMs in two directions (HD Wave) is now available in multiple geographies. The sensitivity of this technology for periprocedural identification of gaps in PVI lines has not previously been compared to the technique of pacing the ablation lines.

Purpose

 To assess the utility of a high-density grid-style catheter for confirming PVI, and to evaluate sensitivity for identification of gaps relative to a technique of pacing the ablation lines.

Methods

 Self-reported procedural data was prospectively collected in atrial fibrillation ablation procedures. Cases in which pulmonary vein isolation was confirmed by pacing the ablation line and subsequently assessed with HD Grid were selected for analysis. Techniques for PVI confirmation were analyzed and the incidence and location of residual gaps following PVI confirmation via pacing was quantified.

Results

 A total of 22 AF ablation procedures (age 60.1 ± 9.0 years, LVEF 59.3 ± 5.7%, CHADS 1.5 ± 1.4, hypertension 45.5%) across 5 centers in Italy and the United States were analyzed. De novo and repeat ablations represented 72.7% and 22.7% of cases, respectively (4.5% not reported). PVI was confirmed by pacing along the ablation line with an average output of 8.8 ± 1.9mV and pulse width of 2.2 ± 0.7ms (10mv at 2ms utilized in 59.1%). Subsequent PVI assessment was performed with HD Grid using the HD Wave configuration in all cases. PVI confirmation techniques included exit block confirmation (90.9%), voltage mapping (59.1%), loss of pace capture along ablation lines (40.9%), entrance block confirmation (18.2%), and activation mapping (4.5%); note: total exceeds 100% as more than one technique may be employed in a single case. The HD Grid identified a total of 30 gaps in 15 (68.2%) patients, which were initially missed by pacing along the ablation lines. No adenosine or isoproterenol use was documented in any case.

Conclusion(s): Use of the HD Grid appears to increase substantially, the sensitivity for identifying gaps in PVI lesion sets relative to a technique of pacing the ablation line. Limitations of this analysis include small sample size and workflows which consistently assessed PVI with the HD grid following confirmation of isolation by pacing the ablation lines. Despite these limitations, the high prevalence of residual gaps is quite provocative and may warrant additional study.

Abstract Figure.