Background: High power short duration radiofrequency ablation (RF) ablation can improve the creation of predictable permanent lesions for ablation of atrial fibrillation (AF). However, lesion created by high power and ultra high power may have a limited lesion depth. Therefore, we investigated an ablation protocol using ultra high power at thin left atrial myocardial tissue and more conventional RF power at thicker myocardial tissue in the circumferential pulmonary vein isolation (PVI).

Methods: Consecutive patients (pts) with indication for de novo AF ablation (n=38, 66±10 years) with paroxysmal (n=23) or persistent (n=15) AF underwent high density 3D mapping of the left atrium (PentaRay, CARTO, Biosense Webster) and RF catheter ablation (Qdot, Biosense Webster). Low voltage areas (bipolar voltage < 0.5 mV) of more than 5% of the left atrium were found in 32% of pts. Thereafter, ipsilateral PV encircling with different RF power applications targeting an interlesion distance of ≤ 6mm, a contact force of 5-30g was performed. Esophageal temperature measurement (Sensitherm, Abbott) was performed. 90 Watt (W)/4 s application were applied at all points around the circumferential line where bipolar voltage was less than 2.0 mV, but not at the anterior entrance of the carina of the right and left pulmonary veins. At these positions conventional ablation index-guided 35 W RF applications were applied, as well as at points of failing first pass isolation. At large bipolar voltage (>2.0 mV) beyond the anterior carina entrance, 50 W short duration application were performed. At positions of the posterior wall adjacent to the esophagus the ultra high power RF application was shortened to 3s. 

Results: Left atrial mapping lasted 15±6 min. Using 88±17 RF applications (78±16 with 90 W, 7±4 with 50 Watt and 3±4 with 35 Watt) pulmonary vein encircling was performed in 31±6 min. Validation of the lines and completion of lines lasted 7±3 min. First pass isolation for both circles was successfully performed in 74% of cases. During waiting period and adenosine challenge, only in 2 pts (5%) pulmonary vein conduction recurred. Although shortening of 90 W RF application to 3s adjacent to the esophagus, in 34% of patients a temperature rise was noted of up to 41.0°C. These short RF applications at the posterior wall did not give reason for recurrence of conduction. No serious complication occurred.  Follow-up of patients will be presented at time of presentation.

Conclusion: Differential use of ultra high power and high power short duration RF application for pulmonary vein isolation and in addition conventional ablation index-guided RF ablation at the thickest atrial layers at the anterior entrance of the carinae of the right-sided and left-sided pulmonary veins is highly efficient and safe, as proved by high first pass isolation rates of pulmonary veins and very low pulmonary vein reconduction during adenosine challenge.  Nevertheless, further follow up and outcome data have to be awaited.