Background
Pulmonary vein isolation (PVI) using radiofrequency-ablation (RFA) in patients with paroxysmal atrial fibrillation (PAF) is effective but hampered by PV reconnection due to insufficient ablation lesions. Recently published data showed that high power delivery over a short period of time (HPSD) in RFA is more efficient with a comparable safety profile while reducing procedure and RF time. Two HPSD ablation modes are available at the moment. In a temperature controlled ablation mode novel ablation catheters with very distal temperature probes allow automated flow and power adjustments depending on the local tissue temperature. In a power controlled ablation mode using conventional ablation catheters with rather proximal temperature probes, power is ramped up to e.g. 70 watts without automated temperature dependent adjustments of flow or power (Figure 1). Aim of this study was to compare intraprocedural and biophysical data as well as periprocedural safety of HPSD ablation in patients undergoing PVI for PAF using either a power controlled or a temperature controlled ablation mode.

Methods

We included n=78 patients with PAF that were scheduled for PVI. We used the QDot catheter (Biosense Webster) in n=38 patients in a temperature controlled HPSD ablation mode with 90 watts for 4 seconds (TC-group). In n=40 patients the Flexability catheter (Abbott) was used with a power controlled ablation protocol of 70 watts and a duration cut-off of 7 seconds at the anterior LA and 5 seconds at the posterior LA (PC-group). Both groups where compared for periprocedural complications and biophysical characteristics.

Results

No pericardial tamponade, no periprocedural thromboembolic complications or atrio-esophageal fistula occurred in either group. Mean RF time was significantly shorter in the TC-group compared to the PC-group with 8.1+/-2.8min vs. 15.3 +/-6.5min (p=0.04). Procedure duration was not different with 100+/-41min in the TC group and 105+/-29 min in the PC group (p=0.09). The mean power was significantly higher in the TC group (81.3W +/- 4.7W vs. 62.6W +/- 4.0W) as well as the mean applied current (876mA +/- 31mA vs. 739mA +/- 60mA) whereas the mean applied energy was significantly higher in the PC group (321J +/- 23J vs. 477J +/- 57J) (Figure 2). There was no difference regarding the mean impedance drop per lesion during ablation (9.5% +/- 0.9% TC group vs. 9.2% +/- 1.4% (PC group)).

Conclusion

In this study TC ablation with 90W for 4 sec. lead to a reduction in RF time whereas procedure duration was comparable. HPSD TC ablation resulted in higher current but less total energy delivery compared to PC ablation. Local impedance drop from baseline was comparable between both groups. Both HPSD ablation modes appeared to be feasible with a comparable safety profile.