The Impact of Additional Ablation Lines on Patients with Low Voltage Areas Undergoing High Power Short Duration Ablation for Atrial Fibrillation

Background:
Circumferential pulmonary vein isolation (PVI) utilizing high power short duration (HPSD) radiofrequency energy has become a standard treatment for atrial fibrillation (AF) patients, resulting in promising clinical outcomes. Nevertheless, enhancing the success rate remains a priority, particularly in patients with extensive low voltage areas. The efficacy of additional ablation lines during initial PVI is still debated.

 

This study examined 202 patients with both paroxysmal and persistent AF who underwent HPSD ablation. When minimal or no fibrotic substrate was present, only PVI was performed (“PVI-only”, n=149 patients). For patients with larger low voltage areas, additional ablation lines were applied beyond PVI (PVI-plus, n=43 patients). A standardized protocol for HPSD ablation was employed: 50W for 15s for PVI and 35W with ablation index for additional lines with a contact force between 3-20g. If typical atrial flutter was concurrently present, the cavotricuspid isthmus (CTI) was also ablated. Two distinct mapping systems were utilized. The ablation endpoint was the complete pulmonary vein (PV) entrance and exit block, and blocked additional ablation lines, confirmed by a high-density catheter. The study's objective was to compare efficacy, efficiency, and safety between patients in the PVI-only and in the PVI-plus group.

 

Baseline characteristics were similar across groups. At the end of the procedure, PV Entry and Exit block, as well as blocked ablation lines, were confirmed in all patients. Those who received additional ablation lines had a higher degree of low voltage area (26.6 ± 28.1% vs. 14.7 ± 22.3%, p<0.01). For additional lines, an anterior mitral line and a roof line was placed in 32.6% respectively and the CTI was ablated in 62.8% of patients. Procedure duration and fluoroscopy time were comparable in both groups, though there was a trend towards longer procedure times in the PVI plus group. The recurrence rate during the first year post-blanking period was consistent between groups (PVI-only: 21.1% vs. PVI-plus: 25.6%, p=0.54). One case of pericardial tamponade necessitating intervention was noted in the PVI-only group. Minor complications like acute post-interventional pericarditis and vascular access issues without intervention were evenly distributed between the groups (PVI-only: 2.7% vs. 4.7%; p=0.22).

 

Additional ablation lines in patients with extensive low voltage areas and in patients with typical atrial flutter can be applied with little added effort and a low complication rate. Despite possessing more fibrotic substrate, patients who received these additional lines did not exhibit a substantially increased AF recurrence rate after one year, suggesting potential benefits of supplementary ablation lines even in first-time PVI. Larger studies to further investigate this effect would be invaluable.