Comparison of continuity index for drag versus point-by-point ablation with the use of proactive esophageal cooling

Abstract Background Proactive esophageal cooling was recently FDA cleared to reduce the likelihood of esophageal injury during radiofrequency (RF) ablation for treatment of atrial fibrillation (AF). Long-term follow-up data have also shown improved freedom from arrhythmia with proactive esophageal cooling compared to luminal esophageal temperature (LET) monitoring during pulmonary vein isolation (PVI). One hypothesized mechanism is the greater lesion continuity attainable with the use of cooling, which can be quantified by the Continuity Index (which increases as continuity decreases). Increasing the Continuity Index increases gap formation, reduces isolation, and leads to greater AF recurrence; however, the difference in Continuity Index between ablating in a point-by-point fashion versus a dragging fashion has not previously been analyzed. Purpose To prospectively measure the Continuity Index of PVI cases and compare the dragging technique to point-by-point technique when using proactive esophageal cooling or LET monitoring. Methods We determined the Continuity Index for 101 patients: 77 prospectively utilizing proactive esophageal cooling, 24 retrospectively recorded using LET monitoring. Cases were completed by four operators, three utilizing point-by-point technique, and one using the drag technique. The Continuity Index was calculated by incrementing one unit for each lesion that did not border the previous lesion during the PVI (simplifying the original description of the Continuity Index). Results For cases using esophageal cooling and performing RF ablation using the drag technique, the average Continuity Index was 8.5 (range: 1 to 14). For point-by-point operators using esophageal cooling, the average Continuity Index was 1.2 (range: 0 to 9), representing a difference of 7.3 between the dragging technique and point-by-point ablation (p < .001). Patients receiving LET monitoring and RF ablation using the drag technique had Continuity Indices of 23.8 (range 15 to 30). Patients receiving LET monitoring and RF ablation using point-by-point ablation had Continuity Indices of 28.4 (range 16 to 50). Figure 1 compares these findings. Only 4 patients (5%) in the esophageal cooling group had a Continuity Index above 6 on either side (all in the dragging group), versus 100% (24) of patients in the LET monitoring group. Conclusion Proactive esophageal cooling during PVI is associated with a high degree of lesion continuity, as represented by the low Continuity Index. The drag technique resulted in a higher index than the point-by-point technique, but both provided significantly lower Continuity Indices (greater lesion continuity) than cases using LET monitoring. This may offer a mechanism for the greater freedom from arrhythmia seen to date with proactive cooling in long-term follow-up.Figure 1.Comparison of Continuity Index